NHS Choices

Does moderate drinking reduce heart failure risk?

NHS Choices - Behind the Headlines - Tue, 20/10/2015 - 12:10

"Seven alcoholic drinks a week can help to prevent heart disease," the Daily Mirror reports. A US study suggests alcohol consumption up to this level may have a protective effect against heart failure.

This large US study followed more than 14,000 adults aged 45 and older for 24 years. It found those who drank up to 12 UK units (7 standard US "drinks") per week at the start of the study had a lower risk of developing heart failure than those who never drank alcohol.

The average alcohol consumption in this lower risk group was about 5 UK units a week (around 2.5 low-strength ABV 3.6% pints of lager a week).

At this level of consumption, men were 20% less likely to develop heart failure compared with people who never drank, while for women it was 16%.

The study benefits from its large size and the fact data was collected over a long period of time.

But studying the impact of alcohol on outcomes is fraught with difficulty. These difficulties include people not all having the same idea of what a "drink" or "unit" is.

People may also intentionally misreport their alcohol intake. We also cannot be certain alcohol intake alone is giving rise to the reduction in risk seen.

Steps you can take to help reduce your risk of heart failure – and other types of heart disease – include eating a healthy diet, achieving and maintaining a healthy weight, and quitting smoking (if you smoke).


Where did the story come from?

The study was carried out by researchers from Brigham and Women's Hospital in Boston, and other research centres in the US, the UK and Portugal.

It was published in the peer-reviewed European Heart Journal.

The UK media generally did not translate the measure of "drinks" used in this study into UK units, which people might have found easier to understand.

The standard US "drink" in this study contained 14g of alcohol, and a UK unit is 8g of alcohol. So the group with the reduced risk actually drank up to 12 units a week.

The reporting also makes it seem as though 12 units – what is referred to in the papers as "a glass a day" – is the optimal level, but the study cannot not tell us this.

While consumption in this lower risk group was "up to" 12 units per week, the average consumption was about 5 units per week. This is about 3.5 small glasses (125ml of 12% alcohol by volume) of wine a week, not a "glass a day".

And the poor old Daily Express got itself into a right muddle. At the time of writing, its website is actually running two versions of the story. 

One story claims moderate alcohol consumption was linked to reduced heart failure risk, which is accurate. 

The other story claims moderate alcohol consumption protects against heart attacks, which is not accurate, as a heart attack is an entirely different condition to heart failure.


What kind of research was this?

This was a large prospective cohort study looking at the relationship between alcohol consumption and the risk of heart failure.

Heavy alcohol consumption is known to increase the risk of heart failure, but the researchers say the effects of moderate alcohol consumption are not clear.

This type of study is the best way to look at the link between alcohol consumption and health outcomes, as it would not be feasible (or arguably ethical) to randomise people to consume different amounts of alcohol over a long period of time.

As with all observational studies, other factors (confounders) may be having an effect on the outcome, and it is difficult to be certain their impact has been entirely removed.

Studying the effects of alcohol intake is notoriously difficult for a range of reasons. Not least is what can be termed the "Del Boy effect": in one episode of the comedy Only Fools and Horses, the lead character tells his GP he is a teetotal fitness fanatic when in fact the opposite is true – people often misrepresent how healthy they are when talking to their doctor.


What did the research involve?

The researchers recruited adults (average age 54 years) who did not have heart failure in 1987 to 1989, and followed them up over about 24 years.

Researchers assessed the participants' alcohol consumption at the start of and during the study, and identified any participants who developed heart failure.

They then compared the likelihood of developing heart failure among people with different levels of alcohol intake.

Participants came from four communities in the US, and were aged 45 to 64 years old at the start of the study. The current analyses only included black or white participants. People with evidence of heart failure at the start of the study were excluded.

The participants had annual telephone calls with researchers, and in-person visits every three years.

At each interview, participants were asked if they currently drank alcohol and, if not, whether they had done so in the past. Those who drank were asked how often they usually drank wine, beer, or spirits (hard liquor).

It was not clear exactly how participants were asked to quantify their drinking, but the researchers used the information collected to determine how many standard drinks each person consumed a week.

A drink in this study was considered to be 14g of alcohol. In the UK, 1 unit is 8g of pure alcohol, so this drink would be 1.75 units in UK terms.

People developing heart failure were identified by looking at hospital records and national death records. This identified those recorded as being hospitalised for, or dying from, heart failure.

For their analyses, the researchers grouped people according to their alcohol consumption at the start of the study, and looked at whether their risk of heart failure differed across the groups.

They repeated their analyses using people's average alcohol consumption over the first nine years of the study.

The researchers took into account potential confounders at the start of the study, including:

  • age
  • health conditions, including high blood pressure, diabetes, coronary artery disease, stroke and heart attack
  • cholesterol levels
  • body mass index (BMI)
  • smoking
  • physical activity level
  • educational level (as an indication of socioeconomic status)


What were the basic results?

Among the participants:

  • 42% never drank alcohol
  • 19% were former alcohol drinkers who had stopped
  • 25% reported drinking up to 7 drinks (up to 12.25 UK units) per week (average consumption in this group was about 3 drinks per week, or 5.25 UK units)
  • 8% reported drinking 7 to 14 drinks (12.25 to 24.5 UK units) per week
  • 3% reported drinking 14 to 21 drinks (24.5 to 36.75 UK units) per week
  • 3% reported drinking 21 drinks or more (36.75 UK units or more) per week

People in the various alcohol consumption categories differed from each other in a variety of ways. For example, heavier drinkers tended to be younger and have lower BMIs, but be more likely to smoke.

Overall, about 17% of participants were hospitalised for, or died from, heart failure during the 24 years of the study.

Men who drank up to 7 drinks per week at the start of the study were 20% less likely to develop heart failure than those who never drank alcohol (hazard ratio [HR] 0.80, 95% confidence interval [CI] 0.68 to 0.94).

Women who drank up to 7 drinks per week at the start of the study were 16% less likely to develop heart failure than those who never drank alcohol (HR 0.84, 95% CI 0.71 to 1.00).

But at the upper level of the confidence interval (1.00), there would be no actual difference in risk reduction.

People who drank 7 drinks a week or more did not differ significantly in their risk of heart failure compared with those who never drank alcohol.

Those who drank the most (21 drinks per week or more for men, and those drinking 14 drinks per week or more for women) were more likely to die from any cause during the study.


How did the researchers interpret the results?

The researchers concluded that, "Alcohol consumption of up to 7 drinks [about 12 UK units] per week at early middle age is associated with lower risk for future HF [heart failure], with a similar but less definite association in women than in men."



This study suggests drinking up to about 12 UK units a week is associated with a lower risk of heart failure in men compared with never drinking alcohol.

There was a similar result for women, but the results were not as robust and did not rule out the possibility of there being no difference.

The study benefits from its large size (more than 14,000 people) and the fact it collected its data prospectively over a long period of time.

However, studying the impact of alcohol on outcomes is fraught with difficulty. These difficulties include people not being entirely sure what a "drink" or a "unit" is, and reporting their intakes incorrectly as a result.

In addition, people may intentionally misreport their alcohol intake – for example, if they are concerned about what the researchers will think about their intake.

Also, people who do not drink may do so for reasons linked to their health, so may have a greater risk of being unhealthy.

Other limitations are that while the researchers did try to take a number of confounders into account, unmeasured factors could still be having an effect, such as diet.

For example, these confounders were only assessed at the start of the study, and people may have changed over the study period (such as taking up smoking). 

The study only identified people who were hospitalised for, or died from, heart failure. This misses people who had not yet been hospitalised or died from the condition.

The results also may not apply to younger people, and the researchers could not look at specific patterns of drinking, such as binge drinking.

Although no level of alcohol intake was associated with an increased risk of heart failure in this study, the authors note few people drank very heavily in their sample. Excessive alcohol consumption is known to lead to heart damage.

The study also did not look at the incidence of other alcohol-related illnesses, such as liver disease. Deaths from liver disease in the UK have increased 400% since 1970, due in part to increased alcohol consumption, as we discussed in November 2014.

The NHS recommends that:

  • men should not regularly drink more than 3-4 units of alcohol a day
  • women should not regularly drink more than 2-3 units a day
  • if you've had a heavy drinking session, avoid alcohol for 48 hours

Here, "regularly" means drinking this amount every day or most days of the week.

The amount of alcohol consumed in the study group with the reduced risk was within the UK's recommended maximum consumption limits.

But it is generally not recommended that people take up drinking alcohol just for any potential heart benefits. If you do drink alcohol, you should stick within the recommended limits.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

Links To The Headlines

Seven alcoholic drinks a week can help to prevent heart disease, new research reveals. Daily Mirror, January 20 2015

A drink a day 'cuts heart disease risk by a fifth' researchers claim...so don't worry about having a dry January. Mail Online, January 19 2015

A drink a night 'is better for your heart than none at all'. The Independent, January 19 2015

Glass of wine a day could protect the heart. The Daily Telegraph, January 20 2015

Daily drink 'cuts risk' of middle-age heart failure. The Times, January 20 2015

Drinking half a pint of beer a day could fight heart failure. Daily Express, January 20 2015

Links To Science

Gonçalves A, Claggett B, Jhund PS, et al. Alcohol consumption and risk of heart failure: the Atherosclerosis Risk in Communities Study. European Heart Journal. Published online January 20 2015

Categories: NHS Choices

Goth teens 'at increased risk of depression and self-harm'

NHS Choices - Behind the Headlines - Fri, 28/08/2015 - 12:23

"Goths are three times more likely to be depressed than other teenagers, with 37% admitting to self-harming," the Daily Mail reports. 

A new study looked at mental health outcomes in young people who said they identified with the goth sub-culture. Goths favour black clothes, stark make-up, gloomy music and an interest in the darker side of life.

The study involved 2,000 teens and looked at whether self-identification as a goth at age 15 is linked to depression and self-harm at 18. 

After full adjustment for prior mental health and behavioural problems in the child, the study found goths were around a quarter more likely to have depression by 18 and a third more likely to report self-harming.

The obvious question is, does being a goth make you prone to depression, or are people already prone to depression more likely to identify with goth culture?

It's likely the relationship between mental health and self-identity is a complex one that cannot be boiled down to a simple "X leads to Y" statement.

And it could even be the case that for some teens who would otherwise have remained socially isolated, adopting the goth sub-culture brings a sense of peer solidarity.

Nevertheless, the study still indicates that those who identify with goth culture may be a group with an increased risk of mental health problems. Providing support to these young people could be beneficial.  

Where did the story come from?

The study was carried out by researchers from the University of Oxford and other academic institutions in the UK. 

It was funded by the Wellcome Trust and the Medical Research Council Programme, and was published in the peer-reviewed Lancet Psychiatry on an open access basis, so it can be read for free online.

The UK media's reporting of this well-conducted research is generally accurate. But an exception to this is The Daily Telegraph, which carried the headline: "Chavs are less depressed than goths, Oxford University finds". This is unsupported by the evidence provided by the study. Rates of depression and self-harm in this group are not given in the paper. 

What kind of research was this?

This cohort study aimed to look at the association between teen self-identification as a goth and depression and self-harm.

Previous research observed that deliberate self-harm is associated with goth culture in young people. However, it is unclear whether this is a direct causative association or whether this link is being influenced by other factors – for example, family, peer or life circumstances.

The researchers aimed to try to look at the direction of effect by assessing self-identity at 15 years and then look for the emergence of new mental health problems at 18 years. 

What did the research involve?

This study involved children enrolled into the Avon Longitudinal Study of Parents and Children (ALSPAC). This is an ongoing study that recruited pregnant women in Avon due to have a baby between April 1991 and December 1992. All children in this study have been invited to attend follow-up assessments every year since the age of seven.

This study included those who took a computer-based survey at the assessment at the age of 15, which asked them to self-identify as one of eight different social groups: sporty, populars, skaters, chavs, loners, keeners, bimbos, and goths.

They were asked further questions about how much they identified with these categories. For example, "Is there a group of teens in your school or neighbourhood with the reputation of rebelling against the norm (in clothing or ideas, for example), or in attempting not to conform to social ideals (e.g. goths)?" and "How much do you identify with the goths?" – to which they answered "not at all", "not very much", "somewhat", "more than somewhat", or "very much".

At the same time they also completed the Development and Wellbeing Assessment, which includes questions about symptoms of depression and self-harm.

Then, at the age of 18, depression was assessed using the Clinical Interview Schedule-Revised (CIS-R), where diagnoses are made according to standard diagnostic criteria from the International Classification of Diseases (ICD). 

This scale also assessed self-harm with questions such as, "Have you ever hurt yourself on purpose in any way (e.g. by taking an overdose of pills or by cutting yourself)?". The researchers didn't make a distinction between whether or not self-harm was associated with suicidal intent.

The researchers looked at the association between goth identification and depression or self-harm at 18 years, adjusting for these factors at 15 years to try to better determine a causative direction of effect. 

They further adjusted their analyses for various individual, family and social characteristics, making use of earlier ALSPAC assessments. This included the mother's history of depression, temperament and educational attainment, as well as the child's earlier history of depression, emotional or behavioural problems, or bullying. 

What were the basic results?

Overall, full data on self-identification and mental health at 15 and 18 years was available for 2,351 teens, who formed the sample for this analysis. This represented just under half of the potential ALSPAC cohort who were still participating in the assessments at 15 years.

Those identifying as goths were more likely to be girls, to have mothers with a history of depression, to have reported being bullied as a child, and to have a history of depression or emotional or behavioural problems themselves.

Depression at 18 years was associated with the extent they identified with goth culture. For example, the depression rate among those who did not identify at all was 6%, compared with 9% of those who identified "somewhat" and 18% of those who identified "very much". After adjustment for confounders, people who identified as a goth were 27% more likely to have depression at 18 years (odds ratio [OR] 1.27, 95% confidence interval [CI] 1.11 to 1.47). The confounder having the greatest influence was previous depression in the teen/child themselves.

There was also a similar link between goth identification and self-harm, with the greater the extent of identification being associated with the highest risk. 

After adjustment for confounders, goths were a third more likely to report self-harm at 18 years (OR 1.33, 95% CI 1.19 to 1.48). A total of 37% of those who "very much" identified as a goth had self-harmed by 18.

As a comparison, for those who identified "very much" with other groups:

  • skaters – 11% with depression and 25% had self-harmed by 18
  • loners – 9% with depression and 26% had self-harmed by 18
  • sporty – 4% with depression and 6% had self-harmed by 18  
How did the researchers interpret the results?

The researchers concluded that, "Our findings suggest that young people identifying with goth sub-culture might be at an increased risk for depression and self-harm."

They go on to say that, "Working with young people in the goth community to identify those at increased risk of depression and self-harm and provide support might be effective." 


This cohort study has found positive links between self-identification as a goth at 15 years, and subsequent depression and self-harm at 18 years.

The study has many strengths, including the use of a large ongoing cohort study, which has carried out regular annual assessments of the mother and child. This has allowed the researchers to adjust their analyses for prior history of mother and child mental health and behavioural problems.

The study also used recognised assessment scales throughout, which has allowed the researchers to make valid clinical diagnoses of mental health problems.

However, the main point is as the researchers rightly say: "Our observational findings cannot be used to claim that becoming a goth increases risk of self-harm or depression". 

The study has made a valid attempt to explore the possible direction of effect by seeing whether identifying as a goth at 15 precedes depression and self-harm at 18 years.

But this still can't prove cause and effect. You can't say, for example, that if this individual hadn't become immersed in goth culture, they would never have developed depression or self-harm behaviours by 18 years.

It could still be the case that personality characteristics, family or peer relationships, or life circumstances may make the teen more likely to be drawn to the goth culture, but may also separately make them more predisposed to depression or other mental health problems.

The self-identification categories on the survey are also quite vague. Even though the researchers made clear attempts to explore the extent the individual identifies with a particular category, each category is still likely to have captured a wide range of personality characteristics and behaviours.

Self-identification is highly subjective, and two people who identify themselves as a goth "very much" may be quite different. It is possible that teens may not have identified particularly with any of these categories and were just having to opt for the one that seemed to be the best fit.

It is also not known how sincerely teens may have responded – for example, people may have called themselves a "chav" or a "bimbo" only lightheartedly.

And although the research and media attention has focused on goths, the findings suggest other groups, such as "skaters" and "loners", may also be vulnerable young people.

Overall, this research cannot prove direct causation, but it still indicates that those identifying with the goth culture may be a group with an increased risk of mental health problems. As the researchers suggest, providing support to these young people could be beneficial. 

Those who may be well placed to recognise young people who may be having emotional or behavioural difficulties – goths or otherwise – include family members and other peers, schools, and youth groups. 

Depression can potentially affect all teens, whether they are goths, Directioners (especially since the One Direction break-up), chavs or sporties. Read more about the possible signs of depression in young people.

Links To The Headlines

Goths are THREE times more likely to be depressed than other teenagers, with 37% admitting to self-harming. Daily Mail, August 28 2015

Chavs are less depressed than goths, Oxford University finds. The Daily Telegraph, August 28 2015

Goth teenagers at higher risk of depression, study suggests. The Guardian, August 28 2015

Young goths 'at risk of depression'. BBC News, August 28 2015

Goths at risk of depression or self-harming, research says. The Independent, August 28 2015

Links To Science

Bowes L, Carnegie R, Pearson R, et al. Risk of depression and self-harm in teenagers identifying with goth subculture: a longitudinal cohort study. The Lancet Psychiatry. Published online August 27 2015

Categories: NHS Choices

How having 'senior moments' may be a good thing

NHS Choices - Behind the Headlines - Thu, 27/08/2015 - 14:30

"Senior moments? Only worry if you don't notice them," the Daily Mail reports.

"Senior moments" is a term used to describe a sudden memory lapse, such as forgetting your PIN or a relative’s name. While these types of lapses can affect people of all ages, older people are often more concerned when they happen, in case they could be the initial symptoms of dementia.

A new study suggests this may be an unnecessary worry – the real warning sign could be when people "forget that they have forgotten". Being unaware of failing memory could be a warning sign of impending dementia.

The study included more than 2,000 older adults from the US and followed them over a period of 10 years. Participants had memory tests every year and were asked to rate their own memory and whether they experienced any problems. During the study period, around 10% of participants were diagnosed with dementia. They experienced a drop in memory awareness around 2.6 years before the development of dementia.

This study highlights the importance of being memory aware – knowing when your memory has let you down on occasion. The researchers state that loss of memory awareness appeared earlier in younger participants; this may be because older people were more likely to expect their memories to fade as a normal part of ageing. Friends and family members should look out for the warnings signs and ensure medical advice is sought if they are concerned. 

Where did the story come from?

The study was carried out by researchers from Rush Alzheimer’s Disease Center and Department of Neurological Sciences, and was funded by the National Institute on Aging and the Illinois Department of Public Health.

The study was published in the peer-reviewed medical journal Neurology. 

This story has been reported both widely and accurately by the UK media. 

The Independent offers a particularly useful report, with additional advice about ways of reducing risk of dementia and highlighting the role of friends and family in aiding medical professionals in diagnosing the condition.    


What kind of research was this?

This study combined people from three prospective cohort studies in the US to investigate the development of memory loss in dementia. The participants were free from dementia at study start; this is the best way to gather information on how a condition develops over time.


What did the research involve?

This study included participants from three longitudinal cohort studies to test whether being unaware of memory impairment is an indicator of dementia.

The participants came from:

  • The Religious Orders Study – older Catholic nuns, priests and brothers.
  • The Rush Memory and Aging Project – older individuals from the Chicago area.
  • The Minority Aging Research Study – older black persons from the Chicago area recruited from the community and the clinical core of the Rush Alzheimer’s Disease Core Centre.

All participants were at least 50 years old and had not been diagnosed with dementia. A number of evaluations were carried out each year. These are as follows:

  • Clinical evaluation – including a medical history, neurologic examination, and tests of memory and cognition. Dementia diagnosis was made by a doctor according to standard criteria.  
  • Self-assessment of memory – Participants were asked two questions about their memory; these were "How often do you have trouble remembering things?" and "Compared to 10 years ago, would you say your memory is better or worse?"
  • Performance testing of memory – 19 cognitive tests were carried out to support clinical classification of dementia and measure change in cognitive function. These included tests of episodic memory (e.g. immediate and delayed recall of word lists) and working memory (e.g. numerical tests).

After death, those who had given consent during the study period had an autopsy of their brain.

The temporal course of memory awareness in dementia was investigated for those people who developed dementia before the end of the study and who had completed at least four annual evaluations.


What were the basic results?

The study included a total of 2,092 older people who had no memory or cognitive impairment at study start. Around 10% of participants (239 people) developed dementia during follow-up and had four annual assessments available from which to assess the course of their memory awareness.

These people had an average age of 79.2 years at study start and were followed up for 10.8 years. This included 7.5 years before dementia onset and 3.3 years after dementia onset. Memory awareness was stable until 2.6 years before the onset of dementia; after this point there was a rapid decline in memory awareness. Participants who were older at study start tended to have later onset of memory unawareness.

Brain autopsy was carried out in 385 of those who died during the study period. Decline in memory awareness could be linked to brain changes that are associated with dementia – such as protein tangles (characteristic of Alzheimer’s disease) and areas where the brain has been starved of oxygen (characteristic of vascular dementia). Where these changes were not found, decline in memory awareness had not been observed.


How did the researchers interpret the results?

The researchers conclude that awareness of memory impairment typically begins to decline about two to three years before dementia onset and is associated with post-mortem evidence of dementia.



This study investigated unawareness of memory loss as an indicator of dementia. The 10% of participants diagnosed with dementia during follow-up who had full assessments available experienced a drop in memory awareness around 2.6 years before the development of dementia. It was also noticed that a drop in memory awareness was associated with the characteristic features of dementia at brain autopsy.

Strengths of this study are the large sample size and long follow-up period. However, there are limitations related to the specific US population samples used. For example, one of the cohorts included only nuns, priests and brothers; another included only people of black ethnicity. These people may have distinct health and lifestyle characteristics, meaning they are not representative of everyone.

In practical terms, it may also be difficult to identify a clear cut-off point between the vague concepts of memory "awareness" and "unawareness". The study also has no direct implications in terms of preventing or slowing the development of dementia.

Nevertheless, the findings highlight the role that friends and family members can have in looking out for signs of unawareness of memory loss, and to ensure medical advice is sought if they are concerned.

Early symptoms of dementia can progress very slowly, so they may not be noticed or taken seriously, just thought to be a normal part of ageing. However, symptoms become more severe as the condition progresses. The speed at which symptoms get worse and the way they develop can depend on the cause and overall health of the person. This means that the symptoms and experience of dementia can vary greatly from person to person.

Memory loss is one of the key symptoms of dementia, but others include:

  • increasing difficulty with tasks and activities that require concentration and planning
  • depression
  • changes in personality and mood
  • periods of confusion
  • difficulty finding the right words

There are no certain ways to prevent dementia. However, you may be able to reduce your risk of developing dementia by following normal healthy lifestyle advice – eating a balanced diet, taking regular exercisenot smoking and drinking alcohol in moderation.

Links To The Headlines

Senior moments? Only worry if you DON'T notice them: Becoming oblivious to memory problems is found to be sign of the onset of dementia. Daily Mail, August 27 2015

Dementia sufferers ‘stop noticing memory loss two years before condition develops'. The Guardian, August 27 2015

Dementia sufferers start losing their memory up to three years before disease takes hold. The Independent, August 26 2015

Worrying about senior moments shows mind is still in good shape. The Daily Telegraph, August 26 2015

Do you have 'senior moments'? Research shows that might not be a bad thing. Daily Mirror, August 26 2015

Forgetting your senior moments is sign of dementia. The Times, August 27 2015 (subscription required)

Why senior moments show you haven’t got dementia. Daily Express, August 26 2015

Links To Science

Wilson RS, Boyle PA, Yu L, et al. Temporal course and pathologic basis of unawareness of memory loss in dementia. Neurology. Published online August 26 2015

Categories: NHS Choices

Low vitamin D levels linked to increased multiple sclerosis risk

NHS Choices - Behind the Headlines - Thu, 27/08/2015 - 10:00

"Lack of vitamin D may cause multiple sclerosis, study finds," reports the Guardian. A large study found people genetically programmed to have lower vitamin D levels are at an increased risk of multiple sclerosis (MS).

MS is a condition where the immune system attacks the coating of nerves in the brain and spinal cord, leading to symptoms such as vision loss, fatigue, and difficulties with balance and co-ordination.

Our body makes vitamin D under the skin in reaction to sunlight. We also get small amounts of the vitamin from our diet in foods such as eggs and oily fish.

A link between vitamin D deficiency and an increased risk of MS has long been suspected, as the condition is more common in areas of the world with less sunlight, such as northern Scotland. But it has been difficult to prove cause and effect because other factors may be involved.

This study used a genetic approach believed to be less susceptible to the problem of confounding – where other factors influence the results.

The researchers learned four genetic variants influence vitamin D levels found in the blood. People can have different combinations of these genetic variations. They found people with a combination of the genetic variations giving them lower levels of vitamin D had double the risk of MS.

But what the study does not tell us is whether MS could be prevented in those at higher risk by increasing their vitamin D levels through taking supplements or other methods.

Find out more about the "sunshine vitamin" in our special report on the health claims made about vitamin D.

Where did the story come from?

The study was carried out by researchers from McGill University and the Jewish General Hospital in Canada; the University of Bristol and King's College London in the UK; and Massachusetts General Hospital and Harvard Medical School in the US.

It was funded by the Canadian Institute of Health Research, The Fonds de la Recherche en Santé Québec, the Lady Davis Institute, the Jewish General Hospital, and the Canadian Diabetes Association.

The study was published in the peer-reviewed journal PLOS Medicine on an open-access basis, so it is free to read online.

The UK media reported the story accurately, and many reports included reactions to the research findings from experts such as Professor Danny Altmann, an immunologist at Imperial College London. 

Professor Altmann said: "While it may be too much to expect therapeutic vitamin D to treat or reverse ongoing MS, this paper will add to the weight of argument for routine vitamin D supplementation of foodstuffs as a broad preventative public health measure." 

What kind of research was this?

This genetic study looked at whether there is an association between genetically influenced levels of vitamin D and the risk of MS.

Previous observational studies found an association between lower levels of vitamin D and MS risk. In particular, MS is more common in people living in geographical areas with reduced sunlight – vitamin D levels are increased by exposing the skin to the sun.

But these studies were unable to prove cause and effect. Questions remain, such as whether the low vitamin D caused MS, or whether vitamin D levels go down in people with MS because they have less exposure to the sun as a result of their condition.

Exposure to sunlight is just one way to increase our vitamin D levels. There is also a genetic component that will have a lifetime influence. This study specifically looked for genetic variations linked to vitamin D levels and whether these genetic variations were also associated with MS risk.

This type of study is called a Mendelian randomisation study because these genetic variations are inherited randomly (each parent will have two copies of each, which one we inherit is random). The term is named after Gregor Mendel, a pioneering 19th century scientist, widely regarded as the father of modern genetics.

The study design means confounding by other factors is not a problem.The researchers in the study took additional steps to be sure this was the case. 

What did the research involve?

The researchers identified genetic variations associated with vitamin D levels using data from the SUNLIGHT study. The Study of Underlying Genetic Determinants of Vitamin D and Highly Related Traits included blood samples from 33,996 people.

They identified four genetic variations associated with lower vitamin D levels. These were close to four genes that create products that have an effect on the level of vitamin D:

  • a protein that binds to vitamin D and carries it in the blood to target organs
  • an enzyme involved in making vitamin D in the body in response to sunlight
  • an enzyme that activates production of vitamin D
  • an enzyme that inactivates vitamin D

They then used data from the Canadian Multicentre Osteoporosis study (CaMos) of 2,347 people to confirm the effect of these four genetic variants on vitamin D levels.

The researchers used the results to investigate the risk of MS depending on the genetic variations a person carried and their genetically determined lifetime level of vitamin D using data from two studies:

  • the International Multiple Sclerosis Genetics Consortium (IMSGC), which has data from 14,498 people with MS and 24,091 healthy controls, all of European descent
  • the IMSGC/Wellcome Trust Case Control Consortium 2 (IMSGC/WTCCC2) study, which has data from 9,772 people with MS and 6,332 controls

The researchers took the following factors into account when analysing the results:

  • age
  • sex
  • body mass index (BMI)
  • time of year the blood sample was taken
  • ethnicity  
What were the basic results?

The four genetic variants associated with reduced vitamin D levels were also associated with an increased risk of MS, with three showing stronger links than the fourth. Each variant was only associated with a relatively small increase in the odds of MS (odds ratio [OR] of 1.04 to 1.11).

Each genetically determined standard deviation decrease in vitamin D levels doubled the risk of MS (OR 2.0, 95% confidence interval [CI] 1.7 to 2.5).

How did the researchers interpret the results?

The researchers concluded: "Genetically lowered 25OHD [a form of vitamin D in the blood] level is associated with an increase in the risk of MS in people of European descent."

They said that: "These findings provide rationale for further investigating the potential therapeutic benefits of vitamin D supplementation in preventing the onset and progression of MS." 


This study found people with a genetic susceptibility to having lower levels of vitamin D have an increased risk of developing MS.

What the study does not tell us is whether MS could be prevented in those at higher risk by taking steps to increase their vitamin D levels. The results also may not apply to people who are not of European descent.

Studies in healthy children and adults are now underway to explore this area. This study does not show what effect taking supplementary vitamin D would have in people who already have MS.

Previous research into vitamin D being used as a treatment for MS and to prevent relapse has been inconclusive because of small study sizes and poor methodology, so large randomised controlled trials are required.

Nevertheless, this piece of research adds to the growing picture that low levels of vitamin D appear to play some part in the development of MS.

You can usually get enough vitamin D through modest exposure of the skin to sunlight (no suntanning required) and a healthy diet that includes oily fish, eggs and foods fortified with vitamin D.

Some people may require vitamin D supplements, such as people aged 65 and over or those not exposed to much sunlight. The NHS suggests that if you take vitamin D supplements, you should not take more than 25 micrograms (0.025mg) a day as it could be harmful.

Find out more about vitamin D.

Links To The Headlines

Lack of vitamin D may cause multiple sclerosis, study finds. The Guardian, August 25 2015

Low vitamin-D genes linked to MS. BBC News, August 26 2015

Why sunlight could protect against multiple sclerosis. The Daily Telegraph, August 25 2015

Links To Science

Mokry LE, Ross S, Ahmad OS, et al. Vitamin D and Risk of Multiple Sclerosis: A Mendelian Randomization Study. PLOS Medicine. Published online August 25 2015

Categories: NHS Choices

Is incense smoke more dangerous than tobacco smoke?

NHS Choices - Behind the Headlines - Wed, 26/08/2015 - 14:30

"Incense may need a health warning over 'toxic' smoke, claims research," The Daily Telegraph reports. Analysis of incense smoke, used in both western and Asian religious ceremonies for possibly thousands of years, found it contains many chemicals, some of which may be harmful.

The researchers – two of whom worked for a tobacco company – tested the residue of tobacco and incense smoke directly on animal and bacteria cells in a laboratory. They did this to see whether they could induce mutations in the DNA and if the smoke was toxic to the cells.

They found the effect of some of the incense smoke tested on the cells was greater than that of the tobacco smoke. However, only four incense sticks and one cigarette were tested, so we have to be cautious about these results.

But incense isn't smoked and so is not drawn directly into the lungs in the way tobacco smoke is, so the effects on lung cells may be very different.

Still, the study is a reminder that burning anything – whether it's incense, coal or tobacco – produces smoke that can irritate and damage the lungs. If you want to make your home smell nicer, we would recommend sticking to air freshener.  

Where did the story come from?

The study was carried out by researchers from the South China University of Technology and the China Tobacco Guangdong Industrial Company.

No information was given about funding. However, the lead researcher worked for the tobacco company, which raises questions about the impartiality of the research.

The study was published in the peer-reviewed science journal Environmental Chemistry Letters, and is available on an open access basis to read online or download as a PDF file.

It was covered cautiously by the Mail Online and The Daily Telegraph, both of which included warnings about the study's links to the tobacco industry. 

What kind of research was this?

This laboratory research used instruments to measure and identify the types of particles and chemicals given off by burning incense.

After measuring the chemicals, the researchers did in vitro studies of the effects of the smoke on bacteria and animal cells.  

What did the research involve?

The researchers burned four incense sticks and one cigarette in a machine that collected particles of smoke through a series of filters. They graded the size of the particles collected, and performed chemical analysis by gas chromatography and mass spectrometry on the contents of the filters. They then tested the smoke residues on cells in petri dishes.

The first test, on salmonella cells, was to see whether the samples prompted mutations in the DNA of the cells. Mutations in DNA can sometimes lead to cancer. The second test used cells from the ovaries of Chinese hamsters to see whether the samples had toxic effects on the cells.

What were the basic results?

Smoke from burning incense created a mixture of fine and ultrafine particles, which are known to be bad for lung health. The chemical analysis found 64 compounds, taking into account all the components of all four incense sticks.

These included chemical components of essential oils and lignin wood, which is commonly used in incense. The compounds were mostly "irritants", although some toxic compounds were found. The paper did not give the equivalent results on particle size and chemical compounds found in the cigarette tested.

The four incense smoke samples and one cigarette smoke sample caused varying degrees of mutation in the salmonella cells. The incense and cigarette smoke was toxic for the hamster ovary cells. Toxicity was maintained at all different levels for the different samples. The incense smoke was toxic at lower concentrations than the cigarette smoke. 

How did the researchers interpret the results?

The researchers showed smoke from some incense samples was "higher than for the reference cigarette sample with the same dose", and said their findings suggest that, "incense smoke was more cytotoxic against Chinese hamster ovary cells" than cigarette smoke.

However, they added: "We cannot simply conclude that cigarette smoke is less cytotoxic than incense smoke, firstly because of the small sample size analysed in this study, and secondly because of huge variability in the consumption of incense sticks and cigarettes." 


This laboratory study found smoke from burning incense can produce fine particles and chemical compounds of a type that may irritate the lungs and damage health. This is not surprising, as most types of smoke indoors produces fine particles that are likely to have this effect, whether from cooking, smoking tobacco, or burning incense.

The suggestion that incense smoke might be more harmful than cigarette smoke needs to be treated with caution. The four incense stick samples had different effects when tested for the ability to mutate cell DNA and toxicity to cells. These were compared with just one cigarette.

This means we cannot draw conclusions about whether most incense sticks produce smoke that is more or less toxic than most cigarettes. Also, research using animal cells in the laboratory is not the same as research on living humans. Adding substances to cells in a petri dish can cause very different effects from what happens when people come across these substances in a dilute form in the environment.

The way we use incense and tobacco is different. Cigarette smoke is drawn directly into the lungs and held there before being exhaled. Incense smoke is burned into the environment and inhaled from the surrounding air. The amount of smoke that gets into the lungs will depend on how much incense is burned, for how long, and on the size and ventilation of the room.

The association of the lead researcher with a tobacco company raises another point of concern. While the researchers stop short of saying incense is more dangerous than cigarettes, it is in the interests of the tobacco company for people to think cigarette smoking and incense burning are on a par – which is not the case.

It seems sensible that people who have lung conditions should avoid using incense, and the rest of us should limit its use for personal reasons, such as improving the smell of your home.

Smoking tobacco, which is known to cause illness and death from conditions including heart diseaselung cancer and stroke, is something everyone should stop altogether.

Read more advice on how the NHS can help you quit smoking.

Links To The Headlines

Incense may need a health warning over 'toxic' smoke, claims research. The Daily Telegraph, August 25 2015

Could incense be more toxic than cigarette smoke? As they burn, 'sticks release compounds that are linked to cancer'. Mail Online, August 26 2015

Links To Science

Zhou R, An Q, Pan XW, et al. Higher cytotoxicity and genotoxicity of burning incense than cigarette. Environmental Chemistry Letters. Published online August 24 2015

Categories: NHS Choices

Researchers 'a step closer' to universal flu vaccine

NHS Choices - Behind the Headlines - Tue, 25/08/2015 - 15:10

"Universal flu vaccine comes closer, scientists say," BBC News reports after two independent teams of researchers each found ways to target multiple strains of the influenza virus – but, as yet, the research has only involved animals.

Because there are many different strains of flu and they constantly change, people need to be vaccinated with a different flu vaccine every flu season. Scientists would like to be able to develop a universal flu vaccine that would be active against all strains of the virus.

The studies developed two different vaccines. Both vaccines were able to protect mice against what would usually be a lethal dose of flu, and one vaccine reduced fever symptoms in monkeys. Both vaccines were based on the principle of attacking specific sites on the virus that are less likely to mutate as new strains come along.

This analysis focuses on the second study, which advanced as far as testing on monkeys, as these results are more likely to apply to humans.

We can't yet be certain that the vaccines will be effective or safe until they are tested on humans, and more animal and lab research will be needed before this can be started.

However, it seems likely that this avenue of research could eventually lead to better flu vaccines at some point in the future. Until then, one simple way to reduce your chances of getting flu is to regularly wash your hands.

Get more flu prevention advice

Where did the story come from?

One of the studies was carried out by researchers from the Crucell Vaccine Institute at the Janssen Center of Excellence for Immunoprophylaxis in the Netherlands and other research centres in the US.

Some parts of the study were supported by the US Department of Energy, National Institutes of Health and National Institute of General Medical Sciences. Various companies provided supplies or input into early designs.

The authors noted that Crucell Holland B.V., a Janssen company, has pending patent applications in this area of research.

The study was published in the peer-reviewed journal Science Express.

The second study was carried out by researchers from the National Institutes of Health in the US, BIOQUAL Inc, and Osaka University in Japan. A patent application has been filed as a result of the study. It was published in the peer-reviewed journal Nature Medicine.

In general, UK news sources have covered the story well, pointing out that the research was in animals and that human vaccines based on this research may still take years to develop.  

What kind of research was this?

This laboratory and animal research aimed to develop a universal flu vaccine. There are many different flu strains and the flu virus is constantly changing.

This has meant that people need to be vaccinated with a different flu vaccine every flu season, which is targeted at the strain or strains expected to be circulating at that time. Scientists would like to be able to develop a universal flu vaccine that would be active against all – or at least most – strains.

This animal research is an essential first step towards developing human vaccines, identifying whether the vaccines look safe and effective enough to go on to human trials. These animal studies usually start in smaller animals such as mice, and if they are successful go on to be tested in primates, whose biology is more similar to humans'. 

What did the research involve?

The flu virus is shaped like a ball, with many "spikes" sticking out of its surface made of a chemical called haemagglutinin. The "stem" part of this spike does not change as much as its tip or other parts of the virus, so both of these studies aimed to develop a vaccine that targeted the stem.

Broadly neutralising antibodies have been discovered in humans, and are active against many flu viruses. Most of them bind to the haemagglutinin stem.

The researchers therefore wanted to create a vaccine that would mimic a section of this stem to stimulate the immune system to produce these types of antibodies. This would prepare the immune system to deal with different types of flu virus in the future.

The first study developed various candidate molecules based on different parts of the haemagglutinin stem using a form of haemagglutinin called HA1. Researchers tested whether the molecules showed similar structures to the corresponding part of the stem in an intact virus, and whether they could bind to antibodies against the stem.

Based on this, they picked the best candidate molecules for testing as vaccines on animals. First, the researchers vaccinated mice, then injected them with what would usually be a lethal dose of flu virus, to see whether they died. In these experiments, they used various different strains of flu to see how well the vaccine protected against them.

The researchers then tested the best-performing vaccine in crab-eating macaques – a type of monkey found in southeast Asia. They injected six monkeys with three doses of the vaccine, and then injected them with a non-lethal dose of flu virus.

They also injected the flu virus into 12 control monkeys. Half of the control monkeys received a human flu vaccine, while the other half received dummy inactive injections. The researchers looked at how ill-vaccinated and unvaccinated monkeys became.

The people assessing the mice and monkeys were not blinded as to which vaccine the animals received – ideally, they would have been blinded to ensure their views could not influence the results.

The researchers also looked at whether the antibodies the vaccinated mice and monkeys were producing bound to a wide range of different flu virus strains in the lab. The antibodies need to be able to bind to the virus strains to have an effect in fighting them.

In the second study, researchers carried out similar experiments to develop and select a candidate molecule based on the H1 haemagglutinin stem region to use as a vaccine. This vaccine, called H1-SS-np, utilised this molecule to bind to tiny particles of a chemical called ferritin (nanoparticles). The researchers then tested it in mice and ferrets. 

What were the basic results?

The first study found good candidate molecules produced high levels of an immune response when injected into mice, which is needed if a vaccine is going to work. Some of the vaccines gave better protection against a potentially lethal dose of flu than others.

One molecule, called mini-HA #4900, prevented 90% of the vaccinated mice from dying after one injection, and after two injections all vaccinated mice survived without losing weight or showing flu symptoms. It showed this protection against an H1N1 flu virus, which is a different H1 strain from the one used to develop the molecule, as well as an H5N1 strain, which has a different type of haemagglutinin.

The researchers went on to test mini-HA #4900 in monkeys. The vaccine again produced high levels of immune response. The antibodies produced could bind to a wide range of different flu virus strains in the lab, including H1 strains and H5N1, as well as some – but not all – group 2 flu viruses. Group 2 viruses have a different haemagglutinin structure from group 1 viruses such as H1N1 and H5N1.

Monkeys vaccinated with mini-HA #4900 had less fever in the first three to eight days after exposure to the flu virus than those vaccinated with either the dummy or human flu vaccines. One of the monkeys in the mini-HA #4900 group was excluded from the analysis because data collection failed.

The second study also identified a candidate vaccine that could produce antibodies in mice and ferrets, which reacted against a variety of flu strains. The vaccine could fully protect mice against a lethal dose of H5N1 flu, and partially protected the ferrets. 

How did the researchers interpret the results?

The researchers in the first study concluded that, "These results provide proof of concept for design of [haemagglutinin] stem mimics that elicit [broadly neutralising antibodies] against influenza A group 1 viruses."

In the second study, the researchers concluded that, "Vaccination of mice and ferrets with H1-SS-np elicited broadly cross-reactive antibodies that completely protected mice and partially protected ferrets against lethal heterosubtypic H5N1 influenza virus challenge." 


These studies have developed two different flu vaccines that could potentially offer broader protection against a variety of flu strains than current vaccines.

As yet, this research has only been conducted in animals, with one study showing an effect against different flu strains in mice and monkeys, and the other showing an effect in mice and ferrets.

As monkeys are more similar to humans than mice or ferrets, the results from these experiments are likely to be the most representative of what would happen in humans.

While the results are encouraging, it is likely that additional lab and animal research on both vaccines will be undertaken to ensure the vaccine's safety and effectiveness before they reach testing on humans. The results suggest that while the vaccines may provide broad protection, they still may not be able to protect against all flu viruses.

As there are many different flu strains and the flu virus is constantly changing, different flu vaccines are needed every flu season. Research like this aims to get us close to a universal flu vaccine that would be active against all – or at least most – strains.

While the vaccines tested in these studies have not yet proven to be effective in humans, it seems likely that this type of research could eventually lead to better flu vaccines. 

Links To The Headlines

Universal flu vaccine comes closer, scientists say. BBC News, August 24 2015

Universal flu vaccine a step closer as scientists create experimental jabs. The Guardian, August 24 2015

Scientists are 'one step closer' to creating a universal flu vaccine: New jab could protect against ALL strains of the virus. Mail Online, August 24 2015

Flu: Breakthrough as multi-strain vaccine raises prospect of 'universal' protection against virus. The Independent, August 24 2015

Links To Science

Impagliazzo A, Milder F, Kuipers H, et al. A stable trimeric influenza hemagglutinin stem as a broadly protective immunogen. Science Express. Published online August 24 2015

Yassine HM, Boyington JC, McTamney PM, et al. Hemagglutinin-stem nanoparticles generate heterosubtypic influenza protection. Nature Medicine. Published online August 24 2015

Categories: NHS Choices

Many white English and Irish pensioners 'drinking to excess'

NHS Choices - Behind the Headlines - Mon, 24/08/2015 - 13:00

"One in five people over 65 who drink is consuming an "unsafe" level of alcohol, say researchers," BBC News reports. Their research also found that "unsafe drinking was far more common among the white British and Irish population".

The study involved nearly 28,000 older adults (aged 65 and over) living in the Lambeth area of London. It found that people were more likely to drink alcohol above safe limits if they were male, aged closer to 65, of Irish ethnicity and higher socioeconomic status.

The researchers used anonymised data from almost all GP practices in this inner-city area. They found that a third of older adults drink alcohol and that 7% drink above safe limits. The research was reliant on GP records, so may in fact be an underestimate, as people are often reluctant to disclose the actual amount of alcohol they consume, due to concerns about stigma. The figures may not be representative of what would be found in other parts of the UK.

The recommended safe limits of alcohol consumption for men are up to 21 units per week, and for women it’s 14 units per week. "Social drinking" can often sneak up on you and lead to conditions such as alcoholic liver diseaseobesity and depression.

If you are concerned about your alcohol consumption, read more practical advice on how to cut down.


Where did the story come from?

The study was carried out by researchers from the Institute of Psychiatry and King’s College London. No external funding was reported.

The study was published in the peer-reviewed medical journal BMJ Open and the study is free to access online.

In general, the media reported the story accurately, though headlines such as, "one-fifth of over-65s drinking at unsafe levels" from The Guardian are misleading. The study found that one-fifth (about 20%) of over-65s who drank any alcohol at all were drinking at unsafe levels. As only a third of over 65-year-olds drank alcohol in this study, this equates to a lower figure of 7%, which is around 1 in 14.


What kind of research was this?

This was a cross-sectional study looking at the level of alcohol consumption in older adults according to age, sex, ethnicity, health and socioeconomic deprivation.

It aimed to see which factors are most associated with high alcohol intake in this population, to inform which groups of people to target with intervention programmes. There has previously been little research of this type in this age group.

As this was a cross-sectional study, it can only look at information from one time point, so it cannot show that the increased alcohol intake caused any of the health problems listed. However, it can show that people drinking alcohol excessively are more likely to experience these conditions.


What did the research involve?

The researchers looked at anonymised data from all adults aged 65 and over from 49 of 50 GPs in the Lambeth inner-city area of London participating in the Lambeth DataNet project – an ongoing project that makes use of anonymised GP data to track and study health trends. 

This current study consisted of 27,991 people in 2013, the study looked at data on their:

  • age
  • gender
  • ethnicity
  • socioeconomic deprivation
  • long-term medical conditions
  • alcohol consumption

Socioeconomic deprivation in the area where each person lived was measured using the Index of Multiple Deprivation 2010 – a government-funded project that measures levels of deprivation and the consequences. For a given area, this looks at:

  • income deprivation
  • employment deprivation
  • health deprivation and disability
  • education skills and training deprivation
  • barriers to housing and services
  • living environment deprivation
  • crime

The data was then analysed to look for associations between these factors and people drinking over the safe limits (21 units a week for men and 14 units a week for women).


What were the basic results?

A third of older adults drank alcohol, (9,248 people) and 7% drank above safe limits, (1,980 people). The factors most likely to predict drinking alcohol and drinking above safe limits were:

  • younger age
  • male gender
  • Irish ethnicity

People were less likely to drink alcohol if they were of Asian, black Caribbean or black African ethnicity.

Socioeconomic deprivation and medical conditions such as high blood pressure did not significantly predict whether someone was drinking above safe limits. However, for those who were drinking above safe limits, less socioeconomic deprivation predicted higher levels of alcohol consumption.


How did the researchers interpret the results?

The researchers concluded that there were "higher levels of alcohol misuse in the 'baby boomer' cohort than in younger age groups". They say that their findings "suggest that close attention needs to be paid to identifying alcohol misuse in 'young older' men, paying close attention to the needs of those born outside the UK and those living in areas of lower deprivation".



This cross-sectional study found that in the over-65s in an inner city area in London (Lambeth), people were more likely to drink alcohol if they are male, in the younger age bracket and of Irish ethnicity. These factors and less socioeconomic deprivation were also predictors of unsafe drinking levels in those who drank.

The findings of this study are important, as they could help to identify people at risk of alcohol-related conditions and provide them with support to reduce their consumption.

However, the study has some limitations. These include a reliance on data recorded by GP services – in particular, self-reporting of alcohol intake, which could be subject to inaccurate recall or reluctance to give true estimates due to stigma. The true figures of alcohol consumption are likely to be higher.

This study was conducted on an inner-city area in London, so results may differ for people living in other geographical areas. For example, there was a higher percentage of people with Irish ethnicity in this area – 5% compared to 1.7% of the general UK population.

If you are drinking above the safe levels recommended for men and women, you can find advice on how to cut down.

Links To The Headlines

Elderly people warned over alcohol consumption. BBC News, August 24 2015

Middle class pensioners risking health by drinking a bottle of whisky a week. Daily Telegraph, August 24 2015

Baby boomers at risk of becoming problem drinkers in their old age, study says. The Independent, August 24 2015

One-fifth of over-65s drinking at unsafe levels, say experts. The Guardian, August 24 2015

Affluent over-65s more likely to drink at dangerous levels: One in five breach guidelines on safe levels of consumption. Daily Mail, August 24 2015

Alarm at over-65s who risk health with booze. Daily Express, August 24 2015

Wealthy pensioners are the most likely to drink too much. The Times, August 24 2015 (subscription required)

Links To Science

Rao R, Schofield P, Ashworth M. Alcohol use, socioeconomic deprivation and ethnicity in older people. BMJ Open. Published online August 24 2015 

Categories: NHS Choices

Warnings of a dementia epidemic may be unfounded

NHS Choices - Behind the Headlines - Fri, 21/08/2015 - 14:30

"Dementia may not be the fast-growing epidemic it has been painted to be," The Guardian reports. Latest data from Europe shows the percentage of dementia cases have levelled off, rather than increased.

However, as the elderly population is growing, the actual number of people with dementia will continue to rise, though perhaps not to the levels of a "dementia epidemic", as previously predicted. 

What is the basis for these reports?

This headline, among others, was prompted by a new "Policy View" article published in the peer-reviewed medical journal, The Lancet: Neurology.

The article looks at five cohort studies assessing the prevalence of dementia over the decades in the UK, Netherlands, Spain and Sweden. It was written by researchers from the University of Cambridge, the University of Newcastle, and institutions in Sweden, Germany and Spain.

The researchers found evidence dementia rates may not be increasing, as had been predicted, but are remaining stable – and could even be falling. 

What did the researchers do?

The researchers analysed the results of five cohort studies comparing dementia rates from the 1970s to 1990s with those done at least seven years later. Only studies with past and more recent dementia estimates that could be directly compared with each other were included.

These cohort studies involved similar older age adults at different time points in the following places:

  • Cambridgeshire, Nottingham and Newcastle in the UK
  • Stockholm and Gothenburg in Sweden
  • Zaragoza in Spain
  • Rotterdam in the Netherlands

For example, in the UK, the study looked at the prevalence of dementia in a random sample of 7,635 adults aged 65 and over who were followed up from 1990-95, comparing this with a similarly random sample of older adults who were followed up from 2008-11. This study adjusted the results to take age, sex and social deprivation into account.

This comparison study from the UK was the largest, with the others ranging from 707 to 7,528 people. The Spanish research compared cohort studies that were conducted with the shortest time gap between them – just seven years – whereas others, such as the Gothenburg study, spanned three decades. The age range for the studies was 55-70 at the start of the cohorts. 

What were the results?

The overall prevalence of dementia measured in the UK from 2008-11 was nearly a fifth (22%) lower than the prevalence from 1990-93. In the 1990 cohort, the prevalence for men and women was 8.3%, compared with 6.5% in the later study (ratio 0.7; 95% confidence interval [CI] 0.6 to 0.9).

There was no significant change in the overall prevalence of dementia in the other four comparison studies. However, the prevalence of dementia in men from Spain reduced by more than half from 5.8% to 2.3% (ratio 0.4, 95% CI 0.3 to 0.7).

In each country the prevalence of dementia approximately doubled with every five years of increasing age. 


What do the results really mean?

The researchers say the results suggest a possible decrease in the occurrence of dementia. They say this may be the result of prevention and health promotion policies aimed at reducing the risk of dementia, such as the stop smoking campaigns seen in recent decades.

While this is possible, the study relies on the results of cohort studies, which cannot prove cause and effect. In addition, this was not a systematic review of all the available evidence on the rates of dementia, but focused on a select number of studies, which limits the interpretation of the findings.

This study's strengths include that it picked studies that used the same study methods between two points in time to measure a change in dementia prevalence. But this has the downside of restricting the evidence to only those that fulfil this criteria – in this review it was just five studies. There may be other studies providing more accurate estimates of dementia at single points in time. These would not have been included here.

We should not take this study to mean that UK dementia prevalence rates are definitely in decline. The results tentatively suggest they might, as well as highlighting the need for more accurate and up-to-date information on dementia prevalence, and to constantly challenge the assumption that the prevalence of the disease is rising. Only good data will settle the debate.

It is important that we don't get complacent about the potential toll dementia could take on public health. While some risk factors, such as smoking, are in decline, others – particularly obesity – may lead to an upsurge in cases. 

How can you reduce your risk of dementia?

Strategies you can take to reduce your risk of dementia include:

  • stopping smoking (if you smoke)
  • being physically active
  • maintaining a healthy weight
  • having a diet that includes plenty of fruit and vegetables
  • keeping your blood pressure under control

Read more about how to prevent dementia

Links To The Headlines

Dementia not the epidemic it was feared to be, say academics. The Guardian, August 21 2015

Dementia levels 'are stabilising'. BBC News, August 21 2015

Middle-aged winning battle against dementia, Cambridge University study finds. The Daily Telegraph, August 21 2015

Warnings of dementia epidemic could be overblown, admit scientists. The Independent, August 21 2015

Dementia epidemic fears 'out of date' as healthier lifestyles stabilise numbers with disease. Daily Mirror, August 21 2015

Dementia levels 'stabilising' across UK and Europe, study finds. ITV News, August 21 2015

Links To Science

Wu Y, Fratiglioni L, Matthews FE, et al. Dementia in western Europe: epidemiological evidence and implications for policy making. The Lancet: Neurology. Published online August 20 2015

Categories: NHS Choices

Working long hours 'increases stroke risk'

NHS Choices - Behind the Headlines - Fri, 21/08/2015 - 14:00

"People working long hours are more likely to have a stroke, according to analysis of more than half a million people," BBC News reports.

Researchers pooled the data from 25 previous studies that included more than 600,000 individuals who were free from heart disease or other types of cardiovascular disease at enrolment. 

They found the risk of developing stroke increased by a third in individuals who worked long hours (above 55 hours a week) compared with individuals with traditional 9-5 working hours. The association of long working hours with heart disease was less – only a 13% increase.

This study has several strengths, including its large size and the inclusion of published and unpublished studies, which removes the risk of publication bias. But the study does have limitations.

The idea that overwork can lead to serious illness and even death is not a new one. The Japanese even have a word for it – "Karōshi". But it is very difficult to prove direct cause and effect. 

Although the researchers tried to account for some health and lifestyle factors that may influence risk, it is problematic to pin down working hours as the single direct cause of a health outcome.

Overall, the results of these studies show an association between long working hours and the risk of developing heart disease and stroke.  

Where did the story come from?

The study was carried out by researchers from various academic institutions in the UK, Finland, France, Sweden, Denmark, Belgium, Germany and Netherlands.

It was funded by multiple organisations, including the Medical Research Council, the Economic and Social Research Council, and the European Union New and Emerging Risks in Occupational Safety and Health research programme.

The study was published in the peer-reviewed medical journal, The Lancet.

The study has been widely reported in the UK media. Overall, the results are accurately reported, but some of the strengths and limitations have not been fully explained. 

The BBC quoted one of the researchers, Dr Mika Kivimaki, of University College London, who said: "People need to be extra careful that they still maintain a healthy lifestyle and ensure their blood pressure does not increase."

While Dr Shamim Quadir of The Stroke Association is quoted as saying: "Working long hours can involve sitting for long periods of time, experiencing stress, and leads to less time available to look after yourself."

He added: "We advise that you have regular blood pressure checks. If you're at all concerned about your stroke risk, you should make an appointment with your GP or health professional." 

What kind of research was this?

This was a systematic review combined with a meta-analysis that assessed the impacts of long working hours on coronary heart diseases and stroke.

The researchers say previous reviews have shown an association between long working hours and cardiovascular disease. However, these studies have several limitations, including few available studies, lack of adjustment for potential confounding factors, and difficulty in proving the direction of effect (that long working hours have preceded the health outcome).

In this review the researchers aimed to include both published and unpublished studies to avoid any publication bias. They also aimed to only include studies where people were free from disease at the start of the study, exclude disease events that took place in the first year of follow-up to make sure of the direction of effect, take confounding factors into account, and look at the influence of socioeconomic class.

Overall, systematic reviews are the best way to gather all evidence on a particular topic, and meta-analysis pools the data from many studies to give an overall indication of the effect. However, the reliability of the findings is only as good as the quality of the studies included.  

What did the research involve?

Researchers identified 25 eligible published and unpublished studies assessing the association between cardiovascular disease and long working hours. Out of the 25 studies, the researchers judged 17 of them to be of a high quality.

The studies were from the US, Australia, Finland, Denmark, Sweden, the Netherlands, Belgium, Germany, the UK, Northern Ireland, and Israel.

The definition of long working hours was mostly 55 hours or more, though some studies used 45 hours or more. The average follow-up period for heart disease was 8.5 years and 7.2 years for stroke. For heart disease outcomes, the results of all 25 studies were pooled, including 603,838 men and women who were free from heart disease at study start. The analysis for stroke included 528,908 men and women from 17 studies who had not had stroke at enrolment.  

What were the basic results?

The review found an association between long working hours and the risk of developing heart disease or stroke.

When adjusted for age, sex and socioeconomic status, long working hours of above 55 hours a week were associated with a modest 13% increase in risk of heart disease (relative risk [RR] 1.13, 95% confidence interval [CI] 1.02 to 1.26) compared with standard working hours (35-40 hours a week).

An analysis restricted to high-quality studies showed the increased risk of heart disease associated with long working hours was higher among those of low socioeconomic groups (RR 2.18, 95% CI 1.25 to 3.81) than in the intermediate group (RR 1.22, 95% CI 0.77 to 1.95) or the high socioeconomic group, where in fact there was no significant link (RR 0.87, 95% CI 0.55 to 1.38).

For stroke, long working hours were associated with a third increased risk of developing stroke (RR 1.33, 95% CI 1.11 to 1.61). Overall, for stroke there was evidence of an increase in risk as the number of additional hours worked increased.

People working for 49-54 hours also had increased risk (RR 1.27, 95% CI 1.03 to 1.56) compared with people working standard hours. For those working 41-48 hours there was a suggestion of increased risk, but the link was non-significant (RR 1.10, 95% CI 0.94 to 1.28).

The associations were not reported to be influenced by gender or geographical area. 

How did the researchers interpret the results?

The researchers concluded by saying: "Our meta-analysis shows that employees who work long hours have a higher risk of stroke than those working standard hours; the association with coronary heart disease is weaker."

They added: "Our findings suggest that more attention should be paid to the management of vascular risk factors in individuals who work long hours." 


This systematic review with meta-analysis aimed to assess the association between long working hours and the risk of developing heart disease and stroke. 

Overall, the study found longer working hours above 55 hours a week was linked to a third increased risk of stroke. The link with heart disease was weaker. 

It also found the influence of long hours on heart disease risk was higher for those of lower socioeconomic groups than it was for those of intermediate or high socioeconomic groups.

This study has several strengths. This includes the large overall sample size and the inclusion of both published and unpublished studies, which should reduce the risk of publication bias. The researchers also excluded disease events that took place in the first year of the follow-up period to better assess the direction of effect. They have also taken into account various confounding factors.

However, this study still cannot prove cause and effect. Though the researchers adjusted for some common confounding factors, various hereditary, health and lifestyle factors may influence the risk of heart disease and stroke. It is not possible to single out working hours as the direct cause of these events.

The studies included may also vary in the working populations covered, definitions of working hours, and assessment of outcomes (such as medical records or self-reports). The studies also came from high-income countries. This makes it hard to generalise the findings to all people.

It is sage advice that we should aim to maintain a healthy lifestyle through a balanced diet and regular exercise habits. Free time to relax away from work is essential to wellbeing, so it is quite plausible that work stress through long working hours may have detrimental health effects.

If you're concerned your working hours are taking a toll on your health, discuss your concerns with your manager or human resources representative. For most professions, employment law states you shouldn't be made to work more than 48 hours a week unless you choose to do so.

Links To The Headlines

Stroke 'more likely' with long hours. BBC News, August 20 2015

Working longer hours increases stroke risk, major study finds. The Guardian, August 20 2015

Hard work really can kill, as longer hours increase risk of stroke. The Daily Telegraph, August 20 2015

Working long hours can increase stroke risk, research finds. Daily Mail, August 20 2015

Long hours at work increase risk of a stroke, scientists find. Daily Mirror, August 20 2015

Working long hours increase stroke risk, research says. ITV News, August 20 2015

Links To Science

Kivimäki P, Jokela M, Nyberg ST, et al. Long working hours and risk of coronary heart disease and stroke: a systematic review and meta-analysis of published and unpublished data for 603 838 individuals. The Lancet. Published online August 19 2015

Categories: NHS Choices

Just one drink a day 'may raise breast cancer risk'

NHS Choices - Behind the Headlines - Thu, 20/08/2015 - 16:30

"Just one drink a day raises breast cancer risk," is the front page headline in the Daily Mail following the results of a new study. While the health risks of heavy drinking are well established, the effects of light drinking are less clear.

The study, which involved almost 136,000 people, found women who drank the equivalent of a glass of wine a day over a 30-year period were 13% more likely to develop one of the alcohol-related cancers (breast cancer being the most common) than women who didn't drink at all.

The study found low to moderate drinking increased the risk of certain types of cancers already thought to be linked to alcohol, but only among women or people who smoked. Men who didn't smoke and drank moderately had no increased risk of any type of cancer. But these were relatively small risk increases for low to moderate drinking – those for heavier drinking were much greater.

In an accompanying editorial, the lead researcher recommends "women with a family history of breast cancer should consider reducing their alcohol intake to below recommended limits [no more than 2-3 units a day], or even abstaining altogether". And all people, whatever their medical history, are recommended to take a break from drinking a few days a week.  

Where did the story come from?

The study was done by researchers at Harvard TH Chan School of Public Health and Harvard Medical School in the US.

It was funded by grants from the US National Institutes of Health, and was published in the peer-reviewed BMJ. It is available to read free online on an open-access basis.

The research was reported widely in the UK media, but with some confusing contradictions. In part this may be because the study itself made lots of different comparisons, resulting in many different statistics.

The Daily Mail's coverage, which was front page news, was generally accurate but failed to make clear that while the increase in cancer risk for women who drank moderately was statistically significant, it was also relatively small. 

The Independent's claim that men who drank moderately had an increased cancer risk did not make it clear this only applied to men who had smoked.

The Daily Telegraph's headline figure that one drink a day increases breast cancer risk by 15% does not appear anywhere in the study. This may be a rounding up of the 13% increased risk of any alcohol-related cancer for women. Specific risk figures for breast cancer are not given.

The BBC News story is balanced and accurate, and points out that the overall increase in cancer risk is likely to be small for those who stick to the recommended alcohol intake. 

What kind of research was this?

The research was based on two prospective cohort studies that followed large groups of people over time, recording detailed information about their lifestyles and health.

Cohort studies are good at showing whether there are links between lifestyle factors such as how much alcohol you drink and outcomes such as getting cancer. But they cannot prove that one thing causes another, as other factors may be involved. 

What did the research involve?

The researchers used the records of more than 88,000 women and 47,000 men in two long-running US studies of health professionals, which started in 1980 and 1986.

They asked the people involved in the studies questions about their lives, including family history of cancer, their diet, whether they smoked and how much they exercised, and recorded their height and weight.

They followed people until 2010, and looked at how many got cancer during that time. They wanted to know whether people who drank alcohol were more likely to get cancer than people who did not.

The researchers were particularly interested in whether people who drank a small amount of alcohol had a higher chance of cancer. They looked at cancer overall, and then at specific cancers we know are linked to alcohol: bowel cancer, breast cancer, mouth or throat cancer, and liver cancer. Although we know drinking a lot of alcohol is linked to these types of cancer, we don't know whether light to moderate drinking affects the risk.

When analysing the results, the researchers adjusted their figures to take account of the effect of other things that may raise the chance of getting cancer, including smoking, obesity and a family history of cancer. Smoking in particular can affect the results, as people who smoke are more likely to drink alcohol – and drink more of it.

The researchers used US measures of alcohol, which do not convert directly into UK units. They defined light to moderate drinking as less than 15g of alcohol for women and less than 30g of alcohol for men.

One UK unit includes 8g of alcohol – for women, 15g of alcohol is just over 2 units. For men, 30g of alcohol is just under 4 units. One unit of alcohol is about equal to half a pint of ordinary-strength beer, or a small pub measure of spirits. A small glass of ordinary-strength wine is about 1.5 units. UK recommended limits are no more than 2-3 units a day for women and 3-4 units for men. 

What were the basic results?

The study found people who drank alcohol were more likely to get cancer than people who did not drink alcohol. The more alcohol people drank, the more likely they were to get cancer.

For people who drank light to moderate amounts of alcohol, the chances of getting any type of cancer overall were "minimally increased". This means that though there was a suggestive trend for an increased risk, the risk differences between light to moderate drinkers and teetotallers were non-significant, or only on the border of being significant.

However, for cancers known to be linked to alcohol, the picture was more complicated. Women in the study who didn't smoke and drank moderate amounts of alcohol were 13% more likely than teetotal women to get an alcohol-related cancer (relative risk 1.13, 95% confidence interval 1.06 to 1.2).

This was mainly accounted for by breast cancer. Though no risk figures are provided specifically for breast cancer, removing breast cancers from their risk calculations gave a non-significant result. Men who didn't smoke and drank moderately were not more likely to get alcohol-related cancer.

The researchers also looked at whether how often people drank alcohol, or whether they drank heavily on individual days, had an effect. They found the total amount of alcohol people drank was more important than patterns of drinking. 

How did the researchers interpret the results?

The researchers said their results showed that, in women who have never smoked, the risk of breast cancer "increases even within the range of one alcoholic drink a day".

They said people's decisions about whether to drink alcohol, and how much, should take account of factors such as whether they have ever smoked and if they have a family history of alcohol-related cancers.  


The impact of drinking alcohol on health has been debated for years. While some research suggests alcohol can benefit heart health, other findings suggest the negative effects outweigh any positives.

It is clear that heavy drinking is bad for health in many ways, including being linked to a higher chance of getting certain cancers, such as those of the breast, liver and bowel. The big question is the effect of drinking low or moderate amounts of alcohol.

This large study found non-smoking women who drank the equivalent of one small glass of wine a day had a small increased chance of getting one of these alcohol-related cancers – mainly attributed to increased breast cancer risk. But it did not find that light or moderate drinking increased the risk of non-smoking men or women getting any type of cancer in general.

The study benefited from having detailed health information about a large group of men and women, followed for a maximum of 30 years. People were asked about their alcohol consumption at the start of the study and again about every four years, as people's drinking habits may change over time. This makes the results stronger. But there is always a possibility that people will not accurately report how much alcohol they drink.

The researchers adjusted their figures to take account of some of the other things that can affect the risk of cancer. For example, they found that if people smoked, smoking was likely to have a bigger effect on their risk of cancer than drinking.

However, it is possible that the influence of other health and lifestyle factors may not have been fully taken into account. These may be things influencing cancer risk in general, or related to specific cancers.

Some factors known to affect the risk of breast cancer, for example, such as the number of children a woman had, whether she breastfed, and use of the contraceptive pill, were not included. We don't know whether these could have affected the results.

Even if we had all this information, we could not say for sure that there is a set threshold level of alcohol below which it is safe to drink, and above which alcohol will cause cancer. We can only say that, in this large group of people, those who drank increasing amounts of alcohol were more likely to get cancer than those who did not.

The researchers speculated that substances that form when alcohol is broken down by the body could have a toxic effect that may increase the risk of cells turning cancerous. They suggest breast tissue may be particularly susceptible to the potentially harmful effects of alcohol.

In an editorial in the BMJ accompanying the piece, one doctor wrote this study means women with a family history of breast cancer should consider abstaining from alcohol altogether. This advice was widely reported, although the research did not find a stronger link between alcohol and cancer risk for women with a family history of breast cancer. Only 3% of breast cancers are caused by inherited faulty genes, according to Cancer Research UK.

The main finding of this study is that low to moderate drinking may increase a woman's chances of getting alcohol-related cancer by 13%, relative to the chances of teetotal women.

This is a relatively small risk increase, and may be much less than the influence of other factors – some you can change (weight, diet and physical activity), and some you can't (age, gender and hereditary factors). Whether this small increased chance of cancer merits cutting down to less than the current recommended limits, or stopping altogether, depends on your attitude to risk.  

Links To The Headlines

Just ONE DRINK a day raises breast cancer risk: Women who consume alcohol every day increase their chance of developing certain types of the disease by 13 per cent. Daily Mail, August 18 2015

One drink a day increases the risk of breast cancer by 15 per cent. The Daily Telegraph, August 19 2015

Daily glass of wine raises risk of breast cancer in women. The Guardian, August 18 2015

Links To Science

Cao Y, Willett WC, Rimm EB, et al. Light to moderate intake of alcohol, drinking patterns, and risk of cancer: results from two prospective US cohort studies. BMJ. Published online August 18 2015

Categories: NHS Choices

Water fluoridation 'a safe way of stopping tooth decay'

NHS Choices - Behind the Headlines - Thu, 20/08/2015 - 15:20

"Adding fluoride to tap water could save the NHS millions and dramatically improve children's dental health," the Mail Online reports. A new UK study concluded that water fluoridation is a "safe and effective" way of preventing tooth decay in children.

The study used national data to compare the rates of tooth decay and other health outcomes in areas of England where fluoride either has or has not been added to the water.

Primarily, the study seems to confirm what is already well established – fluoride protects against tooth decay. Rates of tooth decay among five and 12-year-olds and hospital admissions for tooth decay in under-fives were significantly lower in water-fluoridated areas.

Whether fluoride could have detrimental effects on other areas of health has been a concern. This study didn't find an adverse effect for any of the outcomes examined. In fact, water fluoridation was linked to small decreases in the rates of bladder cancer and kidney stones, and a tiny reduction in all-cause death. There was also no evidence water fluoridation increased the rates of children born with Down's syndrome.

But we should not automatically assume water fluoridation is protective against bladder cancer, kidney stones and death, as the differences in rates are quite small and could be accounted for by many unmeasured factors.

Overall, the study lends support to the positive effects of water fluoridation on dental health among young children. However, firmer conclusions on possible wider health effects cannot be made. 

Where did the story come from?

The study was carried out by researchers from Public Health England (PHE) and was published in the peer-reviewed journal of Community Dentistry and Oral Epidemiology. No sources of financial support are reported.

In the interests of transparency, it should be made clear that Bazian Ltd carried out an independent analysis of key research submitted to South Central Strategic Health Authority as part of the public consultation on the proposal to fluoridate water in Southampton.

The Mail's coverage is generally accurate, though their article focuses on the effects of child tooth decay. It doesn't cover the aim of this research – to look into other health effects – or cover the limitations of the evidence. Saying that "putting fluoride in the water everywhere would save the NHS millions" is only an assumption. The article also doesn't recognise that in some parts of the UK, fluoride naturally occurs at the recommended levels. 

What kind of research was this?

This was a cross-sectional study that aimed to look at the association between water fluoridation schemes in England and selected health outcomes.

Six million people in England are said to live in areas where the level of fluoride in water has been adjusted, the main reason being to reduce the public health burden of dental caries. Dental caries, or tooth decay, are reported to affect more than one-quarter of young children, with higher rates in areas of greater deprivation.

Fluoride has long been recognised to reduce the risk of dental caries. Water fluoridation schemes in England (mostly introduced from the late-60s to mid-80s) aim to achieve a level of one part fluoride per million (1ppm) in water, with a maximum permitted level of 1.5ppm.

However, while the dental effects of fluoride are well established, what is less known is whether fluoride could have other detrimental health effects or, conversely, possible health benefits. This study aimed to compare rates of dental and other health outcomes in areas of England with and without water fluoridation.  

What did the research involve?

This study used geographical information systems (computer systems used to track and assess data for defined geographical regions) and known patterns of water supply to estimate the level of exposure to fluoridated water in small areas and administrative districts in England.

Fluoride exposure was estimated for small areas (lower super output areas, LSOAs) with a population range of 1,000-3,000, and for administrative districts known as upper tier local authorities (UTLAs) and lower tier local authorities (LTLAs). Areas where the level of fluoride in water naturally reached around 1ppm without added fluoride were excluded.

Health outcomes examined for the regions (and their data source) were as follows:

  • dental caries at five and 12 years old – National Dental Epidemiology Programme for England
  • hospital admissions for dental caries in young children aged one to four years – 2012 Annual Report of the Chief Medical Officers
  • hip fractures – Hospital Episode Statistics (HES) data
  • kidney stones – HES data
  • Down's syndrome – National Down syndrome Register
  • bladder cancer – English Cancer Registration
  • bone cancer – English Cancer Registration
  • overall cancer – English Cancer Registration
  • all-cause death – Office for National Statistics

The time period in which these outcomes were assessed varied for the individual outcome, but was mostly in the 2000s, up to 2010-13.

The associations between water fluoridation and these outcomes were adjusted for potential confounding factors of deprivation and ethnicity. With the exception of child dental caries, other outcomes were also adjusted for age and gender. Down's syndrome was only adjusted for mother's age.  

What were the basic results?

Around 1 in 10 of the LSOAs, LTLAs and UTLAs in England have water fluoridation schemes.

Looking at the dental outcomes, water fluoridation was associated with a significant reduction in the odds of child dental caries (28% reduction for five-year-olds and 21% for 12-year-olds). The rate of hospital admission for dental caries was 42 per 100,000 young children in fluoridated areas, compared with 370 in non-fluoridated areas. This was calculated as a 55% risk reduction.

Looking at other health outcomes, three statistically significant associations were found. Water fluoridation was associated with a reduction in the number of cases of bladder cancer and kidney stones (both 8% reduced incidence) and a small reduction in all-cause death (1.3% reduction).

There were no other associations found for any other health outcomes. 

How did the researchers interpret the results?

The researchers concluded that: "This study uses the comprehensive data sets available in England to provide reassurance that fluoridation is a safe and highly effective public health measure to reduce dental decay.

"Although lower rates of certain non-dental outcomes were found in fluoridated areas, the ecological, observational design prohibits any conclusions being drawn regarding a protective role of fluoridation." 


This cross-sectional study used reliable national data on water fluoridation areas and linked this to registries and databases to see how this influenced the rate of different health outcomes.

Primarily, the study seems to confirm what is already quite well established – fluoride protects against tooth decay. The rate of tooth decay among young children is a particular concern and is a widespread problem across the UK. The study found rates of tooth decay among five and 12-year-olds and hospital admissions for tooth decay in under-fives were significantly lower in fluoridated areas.

The study also aimed to look at whether water fluoridation has any detrimental health effects. It didn't find an adverse effect for any of the outcomes examined. In fact, water fluoridation was associated with decreased rates of bladder cancer and kidney stones. A reduction in all-cause mortality was also found, though this was tiny.

There are, however, important points to keep in mind:

  • This type of study cannot prove cause and effect. Given the known effect of fluoride on dental health, the reduction in rates of child tooth decay in fluoridated areas could be directly attributed to water fluoridation. But this link is not certain. For other health outcomes – as the researchers rightly acknowledge – you can be less sure. You cannot say from this study that fluoridating water definitely protects against bladder cancer or kidney stones, even less so from mortality risk. The risk decreases are relatively small, and there may be many other factors that account for the differences the study has not been able to examine.
  • For rates of child tooth decay, data is limited to the National Dental Epidemiology Programme for England, which gives information only for five and 12-year-olds. Though these may be representative, this still does not cover all children. For under-fives, dental health has been assessed through hospital admissions for tooth decay. This would not cover children who may have tooth decay, but are not admitted to hospital for extractions.
  • The study did not examine an exhaustive list of other health effects. Fluoride may have effects on other areas of health that this study has not examined.
  • The study examined by water fluoridation area. But there is no certainty that the people living in these areas have always lived here. You don't know about their water exposure in other areas of the UK, or elsewhere.
  • Even if individuals had always resided in the area assessed, individual exposure could still vary widely. For example, some people could be drinking regular glasses of tap water throughout the day, while others may not.
  • Also, as the researchers say, they were not able to account for how long the water fluoridation scheme has been in place, which will vary between areas.

Overall, this study lends support to the positive effect of water fluoridation on dental health among young children. However, firmer conclusions on possible wider health effects cannot be made.

Links To The Headlines

Putting fluoride in the water everywhere would save the NHS millions 'by halving the number of people needing tooth extractions'. Mail Online, August 18 2015

Links To Science

Young N, Newton J, Morris J, et al. Community water fluoridation and health outcomes in England: a cross-sectional study. Community Dentistry and Oral Epidemiology. Published online July 8 2015

Categories: NHS Choices

E-cigarettes '95% less harmful than smoking' says report

NHS Choices - Behind the Headlines - Wed, 19/08/2015 - 13:30

"E-cigarettes are 95% less harmful than tobacco and could be prescribed on the NHS in future to help smokers quit," BBC News reports. 

This is the main finding of an evidence review (PDF, 485kb) carried out by Public Health England, a government agency that aims to protect and improve the nation's health and wellbeing, and reduce health inequalities.


What are e-cigarettes?

Most e-cigarettes contain a battery, an atomiser and a replaceable cartridge. The cartridge contains nicotine in a solution of either propylene glycol or glycerine and water, and sometimes flavourings.

When you suck on the device, a sensor detects the air flow and starts a process to heat the liquid inside the cartridge, so it evaporates to form water vapour. Inhaling this vapour delivers a hit of nicotine straight to your lungs.

Unlike "traditional" cigarettes, they do not contain the many dangerous chemicals that can increase the risk of lung cancerheart disease and stroke.


What are the main findings of the review?
  • There has been a rise in e-cigarette use that has been matched by a corresponding decrease in smoking.
  • E-cigarettes are now the most popular quitting aid in England.
  • There is good-quality evidence that e-cigarettes can be effective in helping people quit smoking.
  • While data on their long-term safety is unavailable, expert opinion is that e-cigarettes are around 95% safer than smoking.
  • When used as intended, e-cigarettes pose no risk of nicotine poisoning.
  • E-cigarettes release negligible amounts of nicotine into the environment, and no health risks to bystanders (e.g. passive smoking) have been identified.


What suggestions does the review make?
  • E-cigarettes should not be treated in the same way as normal cigarettes and their use should not be banned in prisons and hospital trusts.
  • E-cigarettes offer the potential of providing a low-cost, effective intervention that could help England’s 8 million smokers to quit the habit for good.
  • Stop smoking services should actively engage with smokers who want to use e-cigarettes to quit.
  • Once e-cigarettes are regulated as medical products – which is expected in 2016 – e-cigarettes could be made available by the NHS on prescription.  

Links To The Headlines

E-cigarettes could be prescribed by the NHS to help smokers quit, report says. BBC News, August 19 2015

Vaping: e-cigarettes safer than smoking, says Public Health England. The Guardian, August 19 2015

Make e-cigarettes available on NHS, say Government health officials. The Independent, August 19 2015

Health chiefs call for free e-cigarettes on the NHS: Review says 76,000 lives could be saved every year if people switched as it is 95% safer than smoking tobacco. Daily Mail, August 19 2015

Call For E-Cigarettes To Be Prescribed On NHS. Sky News, August 19 2015

E-cigarettes on the NHS: A game-changer that could save countless lives. Daily Mirror, August 19 2015

E-cigarettes 'should be prescribed on the NHS' to prevent smoking deaths. ITV News, August 19 2015

Smokers 'to get free e-cigarettes on the NHS' to help them kick the habit. Daily Express, August 19 2015

Categories: NHS Choices

Guidelines set to tackle over-prescribing of antibiotics

NHS Choices - Behind the Headlines - Tue, 18/08/2015 - 14:30

"GPs face axe for handing out too many pills," the Daily Mail reports. The headline is prompted by remarks made by Professor Mark Baker, clinical practice chief at the National Institute for Health and Care Excellence (NICE) which has published new guidelines on antibiotic prescribing.

The guidelines are an attempt to tackle the growing problem of antibiotic resistance.

Increasingly widespread use of antibiotics is leading to the organisms causing these infections adapting and surviving. As this resistance develops, it can render treatments for infections less effective and eventually the infections may become untreatable.


What is antibiotic resistance and how does it develop?

Bacteria evolve in response to their environment. Over time, they can develop mechanisms to survive a course of antibiotic treatment.

This "resistance" to treatment starts as a random mutation in the bacteria’s genetic code, or the transfer of small pieces of DNA between bacteria. If the mutations are favourable to them, they are more likely to survive treatment, more likely to be able to replicate and therefore more likely pass on their resistant nature to future generations of bacteria. 

When taken correctly, antibiotics will kill most non-resistant bacteria, so these resistant strains can become the dominant strain of a bacteria. This means when people become infected, existing treatments may be unable to stop the infections.

Widespread antibiotic resistance could have a far-reaching healthcare impact. For example, emerging antibiotic resistance increases the chance that surgical sites could be infected by bacteria resistant to antibiotics and cause infection in people who may already be vulnerable as a result of their underlying illness or from having surgery.


What recommendations do the guidelines make?
  • Individual health organisations should set up multidisciplinary antimicrobial stewardship teams – a group of health professionals, including a pharmacist and microbiologist, who review the use of antibiotics by that organisation. If patterns of antibiotic prescribing are unusually high, or there is evidence that antibiotics are not being used in line with current guidelines, they would be responsible for exploring why.
  • When prescribing antibiotics, prescribers should provide the shortest effective dose.
  • Prescribers should discuss alternative options to antibiotics with their patients, and if appropriate, explain why prescribing antibiotics may not be the best option.
  • Antibiotics should not be immediately prescribed to patients with a condition that is likely to get better by itself (self-limiting condition). Prescribers should consider whether a back-up prescription could be a more appropriate choice – this is where a patient could get access to antibiotics if their condition does not get better after a set number of days.
  • The use of repeat prescriptions for antibiotics should be avoided, unless there is a clear clinical need. Patients who do require repeat prescriptions should be carefully monitored and reviewed on a regular basis.


Are doctors really going to be 'struck off' for over-prescribing?

Many of the newspapers seized on remarks by Professor Baker, who is quoted as saying, "Most doctors prescribe sensibly and competently. For the relatively small number who are less-disciplined, first we need to identify them, and secondly there need to be processes to deal with them. 

"Ultimately, if they fail to come into line there is always recourse to the professional regulator and there are a number of performance processes that the GMC [General Medical Council] can set to improve the clinical performance of practitioners."

It is likely that doctors would only be referred to the GMC in the most extreme cases.

The guidelines are designed to support and educate health professionals in the appropriate use of antibiotics. It is not a charter for sacking GPs.


How can you help?

Antibiotic resistance is not somebody else’s problem. It is everybody’s problem.

You can help by not requesting them for minor self-limiting conditions – especially coughs and colds, which are likely to be caused by a virus, meaning antibiotics would be of no benefit.

If your doctor does prescribe antibiotics for you, make sure that you’ve discussed and understood how to take them correctly, and that you take all the prescribed pills, regardless of whether you still have symptoms. If you do not take the full prescribed dose, chances are that some of the bacteria will not be killed, and these are more likely to be resistant strains.

Read more about what you can do to tackle the problem of antibiotic resistance

Links To The Headlines

GPs face axe for handing out too many pills: Crackdown as 10 million antibiotic prescriptions dished out needlessly. Daily Mail, August 18 2015

Doctors write 10m needless antibiotics prescriptions a year, says Nice. The Guardian, August 18 2015

Call to punish GPs over antibiotics. BBC News, August 18 2015

'Soft Touch' GPs Give Antibiotics Too Easily. Sky News, August 18 2015

GPs should face disciplinary action for prescribing antibiotics to 'pushy patients', says Nice director. The Independent, August 18 2015

'Soft touch’ doctors should be disciplined for over-prescribing antibiotics. The Daily Telegraph, August 18 2015

Strike off doctors who risk killer bug outbreak by overprescribing antibiotics, says watchdog. Daily Mirror, August 18 2015

Watchdog calls for clampdown on 'soft touch' GPs handing out unnecessary antibiotics. ITV News, August 18 2015

Categories: NHS Choices

Aspirin lowers risk of hereditary bowel cancer in obese people

NHS Choices - Behind the Headlines - Tue, 18/08/2015 - 14:00

"A daily aspirin may slash bowel cancer risk for the obese," the Daily Mail reports. But the headline fails to make it clear that this latest research didn't involve people in the general public who were obese.

It actually involved people at high risk of bowel cancer as the result of a rare hereditary condition known as Lynch syndrome. The majority of those with the condition will develop bowel cancer at some point in their adult lives.

The main finding of this research was that being overweight or obese was associated with a further increase in these people's risk of bowel cancer. However, the study also found body mass index (BMI) did not appear to affect bowel cancer risk in people who had been taking aspirin. This suggested that aspirin might be offsetting the risk of obesity in people with Lynch syndrome.

However, this trial may not be representative of the majority of people, who do not have Lynch syndrome. In addition, there are potential risks associated with regular long-term aspirin use, such as gastrointestinal bleeding. This means the risks of the general public taking aspirin to combat bowel cancer may outweigh any benefits.

Aiming to achieve or maintain a healthy body weight, as well as eating a healthy diet, taking regular exercise and not smoking, are ways you can help to reduce your bowel cancer risk. You should not start taking aspirin regularly without discussing it with your GP first. 

Where did the story come from?

The study was carried out by researchers from Newcastle University and other international research centres.

It was funded by the UK Medical Research Council, Cancer Research UK, the European Union, the Cancer Council Victoria in Australia, the Technology and Human Resources for Industry Programme South Africa, the Sigrid Juselius Foundation, and the Finnish Cancer Foundation.

Bayer and National Starch and Chemical provided drugs and placebos for free and made donations towards running the study.

The study was published in the peer-reviewed Journal of Clinical Oncology and was covered by the Daily Mail, the Daily Mirror and The Times.

None of the newspapers' headlines made it clear that the study was only in people with a rare genetic disease that increases their risk of bowel cancer. This may limit how directly relevant findings are for people who do not have this condition.

The papers also focus on the aspirin results, when the main focus of the study was on assessing the impact of being overweight or obese with Lynch syndrome. However, each paper's reporting did contain useful advice about the risk of self-prescribing without first consulting a doctor.  

What kind of research was this?

Being overweight or obese has been linked to an increased risk of bowel cancer in the general population. This study assessed whether being overweight or obese influenced bowel cancer risk in people with Lynch syndrome. Estimates of its prevalence vary from 1 in 660 to 1 in 2,000.

Also known as hereditary non polyposis colorectal cancer (HNPCC), this condition greatly increases the risk of bowel cancer. The majority of those carrying the gene mutation develop bowel cancer at some point in their adult lives. For this reason, some people with the condition may have preventative treatment to remove all or part of the bowel to reduce their risk.

The study analysed data from a randomised controlled trial (RCT) in people with Lynch syndrome. The RCT (called CAPP2) assessed whether regularly taking aspirin or a form of starch that resists digestion (resistant starch) could reduce bowel cancer risk in these people.

The overall results of this trial, which have already been published, found regularly taking aspirin reduced bowel cancer risk. Behind the Headlines analysed these results in 2011.

The researchers aimed to look at this trial population to see whether being overweight or obese influenced the risk of bowel cancer compared with being a normal weight.

What did the research involve?

The RCT randomly allocated people with Lynch syndrome to receive 600mg aspirin, 30g resistant starch, both, or inactive placebos every day for up to four years (average about two years). Participants were followed for up to 10 years (average 4.6 years) to see if they developed bowel cancer.

People in the trial were 44.9 years old on average and had successfully had cancerous bowel tissue removed without removal of the entire bowel before entry to the trial. They had their BMI measured at the start of the trial – 34% were overweight (BMI 25 to 29.99) and 15% were obese (BMI greater than 30). BMI data was not available for all people in the trial.

In the current analysis, the researchers compared the risk of developing non-cancerous bowel tumours or bowel cancer during the trial in people with different BMIs.

These analyses were adjusted for age, gender, what interventions they were receiving (aspirin or resistant starch), where they lived, and what genetic mutation caused their condition. The researchers also looked at whether the effects of taking aspirin on risk of bowel cancer were influenced by BMI.

What were the basic results?

About 6% of people developed bowel cancer during follow-up. People who were obese were more than twice as likely to develop bowel cancer as those who were normal weight or underweight (hazard ratio [HR] 2.34, 95% confidence interval [CI] 1.17 to 4.67). There was a slight increase in risk in those who were overweight, but this did not reach statistical significance (HR 1.09, 95% CI 0.57 to 2.11).

When the researchers analysed the groups receiving different interventions separately, they found increased BMI was associated with increased bowel cancer risk in those taking the placebo, but not those taking aspirin:

  • Overall, each unit increase in BMI was associated with a 7% increase in risk (HR 1.07, 95% CI 1.02 to 1.13)
  • In the group taking placebo, each unit increase in BMI was associated with a 10% increase in risk (HR 1.10, 95% CI 1.03 to 1.17)
  • In the group taking aspirin, each unit increase in BMI was not associated with a statistically significant increase in risk (HR 1.00, 95% CI 0.90 to 1.12)  
How did the researchers interpret the results?

The researchers concluded that obesity increases the risk of bowel cancer in individuals with Lynch syndrome, but aspirin reduces this risk. They say that these people are likely to benefit from measures to prevent them becoming obese, as well as from taking aspirin regularly.  


This study followed up on a previous trial that found taking aspirin regularly reduced the risk of bowel cancer in people with the genetic condition Lynch syndrome (or HNPCC), which puts them at an increased risk of developing the disease. The study found being obese appears to further increase bowel cancer risk among people with this condition.

It also found that BMI did not appear to have an effect on bowel cancer risk among those taking aspirin. While this might indicate that aspirin removes the effect of BMI, ideally a comparison of aspirin versus placebo in the different BMI groups is needed to further assess this. It is likely that the number of people in this trial who fell into the individual BMI categories was not large enough to show an effect.

However, this trial may not be representative of what would happen if obese members of the general public took aspirin regularly. The people in this trial were at high risk of bowel cancer because of their condition, and obesity appeared to increase this risk further.

Even if taking aspirin can reduce risk in the general public, people may not gain the same benefit as those with Lynch syndrome, and the potential risks associated with aspirin – such as an increased risk of gastrointestinal bleeding – may outweigh any benefits.

We know that being overweight or obese has been linked to an increased risk of bowel cancer and also carries other health risks. Aiming to achieve or maintain a healthy body weight by having a healthy diet that includes plenty of fibre, exercising regularly and not smoking are ways you can help to reduce your risk of bowel cancer. Do not start taking aspirin regularly without discussing the issue with your GP or the doctor in charge of your care.

Links To The Headlines

A daily aspirin may slash bowel cancer risk for the obese: Regularly taking drug reduces chance of developing disease to same level as a person of normal weight. Daily Mail, August 18 2015

Cancer breakthrough as study claims taking aspirin may help obese people avoid killer disease. Daily Mirror, August 17 2015

Aspirin could cancel out cancer risk of being obese. The Times, August 18 2015 (subscription required)

Links To Science

Movahedi M, Bishop DT, Macrae F, et al. Obesity, Aspirin, and Risk of Colorectal Cancer in Carriers of Hereditary Colorectal Cancer: A Prospective Investigation in the CAPP2 Study. Journal of Clinical Oncology. Published online August 17 2015

Categories: NHS Choices

Is your purse a hotbed of bacterial infection?

NHS Choices - Behind the Headlines - Mon, 17/08/2015 - 12:00

"More than 90 per cent of purses have bacteria on them, and women are the worst offenders," the Mail Online reports. A study found purses could be a reservoir for bacteria, especially those made out of synthetic materials.

This study took swabs from the purses of 145 men and women from Mauritius, and tested them for bacteria in the laboratory. It found that bacteria could be grown from almost all purses (95%). The most common types of bacteria identified were Micrococcus and Staphylococcus, followed by Bacillus.

Importantly, these are usually carried harmlessly on the skin of most people. It is only in specific circumstances – for example, if the person has a weak immune system or if the skin is wounded, allowing the bacteria to enter the body – that infection may take place. 

This study has many limitations. One is that it’s a small sample of purses taken from a tropical environment, and the findings may not be representative of the wider population or those from other countries.

We don’t live in a completely sterile environment and ditching the purse or excessively washing it won’t make our environment – or us – bacteria-free. This study should not be a cause for concern for people who own a purse. Remembering to regularly wash your hands, particularly before eating or handling food, is likely to be a better way to reduce our chances of germs spreading that could lead to infection.


Where did the story come from?

The study was carried out by researchers from the University of Mauritius and was published in the peer-reviewed scientific journal Advanced Biomedical Research. No sources of financial support are reported.

The Mail Online’s reporting that purses could be making us sick does not give very reliable coverage of this study or cover the important limitations. A key limitation is that the bacteria grown are naturally found on skin and in the environment, and normally pose no risk to healthy people.

The study did not examine if the bacterial contamination of an individual purse went on to have an effect on a person’s health.

They are also incorrect in saying that "women are the worst offenders" and that "bacteria growth was higher on the purses of women than on those of men". While the researchers do report that bacterial growth was higher on women’s purses, it also reports that the average number of bacterial colonies grown from men’s wallets was higher – so results do not appear to be clear-cut.


What kind of research was this?

This was a laboratory study that swabbed the purses and wallets from a sample of men and women to see what bacteria grew from them under culture (culture, in this context, means creating an environment ideal for the growth of bacteria).

The researchers say that purses are hardly ever washed and are often only thrown out when they become worn out and unusable. What is often not considered is that they could be a breeding ground for bacteria. In fact, all of the things we use in the environment around us, like mobile phones, computers, keyboards and other equipment are all likely to carry some bacteria.


What did the research involve?

The study recruited 145 adults (80 women and 65 men) from the general population in Mauritius. They answered questions on their daily life and work, materials of their purse and frequency of washing their purses. 

They then had swabs taken from the outer surfaces of their purses. These were then swiped across the surface of a gel "plate" in the laboratory, to encourage any bacteria on the swabs to grow. Bacterial growth was assessed after 24 hours, by counting the number of "colonies" – small clumps of bacteria – growing on each plate. 

Fewer than 20 colonies was defined as scanty growth, 20 to 50 colonies as moderate growth, and more than 50 colonies as heavy growth. 


What were the basic results?

Most of the purses sampled (43%) were made of leather; the remainder were synthetic (39%) and cloth (18%). Synthetic purses were more often used by women than men. Only 2% of women (three women) reported washing their purses once a month.

Other purse habits among women were:

  • 11% often placed them on kitchen tables
  • 18% placed them on dining tables
  • 18% allowed their children to handle them
  • 82% never emptied them
  • Most women kept purses in handbags, most men in trouser pockets

The majority of purses sampled (95%) showed bacterial contamination. In about three-quarters (73%) this was scanty growth; 13% showed moderate growth and 14% showed heavy growth. The average number of bacterial colonies grown from each purse was significantly higher for men’s (25 colonies) than women’s purses (19 colonies). However, bacterial growth was said to be higher on women’s than men’s purses. These results appear to conflict with each other, and it was unclear why.

In roughly half of purses, there was only a single type of bacterial growth; in the other half, there was mixed growth. The most common bacteria grown were types of Micrococcus and Staphylococcus, each accounting for around two-thirds, followed by Bacillus (14%). Micrococcus was more common on the men’s purses, while Bacillus was found only on women’s purses.

Synthetic purses showed a higher number of colonies than on leather or material purses. There were no other differences in bacterial growth by age of the purse or occupation of the person. 


How did the researchers interpret the results?

The researchers say that theirs "is the first study to demonstrate that the purses of both women and men from the community could be contaminated with micro-organisms". They also say that these are "potential vectors for transmission of diseases" and that the use of synthetic purses in particular should be discouraged.



This laboratory study looked at the bacteria surrounding us in our environment, this time focusing on sampling carried out on men’s and women’s purses or wallets.

However, before jumping to the conclusion that we need to be either excessively washing our purses, or ditching them altogether and carrying money in our pockets, there are various important points to bear in mind:

  • Considering that the vast majority of adults will own some form of purse or wallet, this was a very small sample of purses being tested. The characteristics found in this sample – such as bacterial levels, or purse use and washing habits – may not apply to the general population.
  • This was also a specific sample of people from Mauritius. The warm, humid, tropical environment may be a different breeding ground for bacteria, compared with colder climates such as the UK.
  • The study only swabbed the outside of the purse. When thinking of the possible bacterial carriage of a purse or wallet, people may think that this could come from the "unclean" coins and notes that have transferred through many hands. However, the study did not swabbed the inside of the purse, which could have given different results.
  • Related to this, it is possible that the researchers could have swabbed almost any surface in the environment and found similar bacterial growth. They chose the outside of the purse. They could have swabbed handbags, keys, money, mobiles, computers, door handles – the list goes on. We don’t live in a completely sterile, bacteria-free environment and we are always surrounded by potential sources of infection. From this study, the purse shouldn’t be singled out as the thing we need to ditch to be completely safe from any bacteria.
  • The researchers have called purses "potential vectors for transmission of diseases". The study does not show that purses directly have or could cause infection. One of the most common types of bacteria grown was Staphylococcus. This is normally carried harmlessly on the skin of most people. It is only in certain circumstances that it causes infection – for example, if the person has a weak immune system through other disease or illness, or if the skin is wounded, allowing the bacteria to enter the body. Similarly, the other two bacteria grown – Micrococcus and Bacillus – are both found in the natural environment and usually carry no risk to humans. As the researchers rightly say, these bacteria have been called "opportunistic" organisms, rarely causing infection in healthy people.

Being, reportedly, the first study to swab and culture bacteria from purses, this research may be of interest, but it should not be a cause for concern for people who own a purse.

Not regularly washing your hands before preparing food or after going to the toilet is probably a bigger threat to your health than having a messy purse.  

Links To The Headlines

Is a dirty purse making you sick? Scientists warn of risk from unhygienic accessories. Mail Online, August 16 2015

Links To Science

Biranjia-Hurdoyal SD, Deerpaul S, Permal GK. A study to investigate the importance of purses as fomites. Advanced Biomedical Research. Published online May 29 2015

Categories: NHS Choices

Low-fat diet 'better' than low-carb diet for getting rid of body fat

NHS Choices - Behind the Headlines - Fri, 14/08/2015 - 12:30

"Low-fat diets 'better than cutting carbs' for weight loss," says BBC News. But wait, the Mail Online says: "Low-carb 'is best for weight loss". Confused?

Traditionally, weight-loss diets were based on the concept of eating a low-fat diet. But in recent years the idea of low or no carbohydrate diets, such as the Atkins diet, have become popular.

A new diet lab rigorously enforced either a low-carbohydrate or low-fat diet for 19 obese men and women over six days. The six-day low-carb diet led to more weight loss than a low-fat diet, but the low-fat diet led to more fat loss. And losing fat tissue is generally better for your health. This means both the BBC and Mail Online are technically correct.

The study was small, short term, and the diets were quite extreme. This makes them less relevant to most people's everyday life or efforts to lose weight. They aren't convincing enough to settle the low-carb versus low-fat diet debate.

But you could argue the whole low-fat versus low-carb debate is a needlessly overcomplicated distraction from what should be four simple words of advice – eat less, exercise more.

The principle of combining physical activity with reduced calorie consumption is at the core of the NHS Choices weight loss plan – a sustainable way to lose weight without relying on any gimmicks.  

Where did the story come from?

The study was carried out by researchers from the US National Institutes of Health and was funded by the same organisation.

It was published in the peer-reviewed science journal Cell Metabolism on an open-access basis, so it is free to read online or download as a PDF (PDF, 1.7Mb).

The BBC and Mail Online ended up with opposite headlines based on the same study. The BBC went with "Low-fat diets 'better than cutting carbs' for weight loss", while the Mail Online said that, "Low-carb 'is best' for weight loss".

This confusion is understandable. The low-fat diet led to more fat loss – the outcome the study was most interested in – but the low-carb diet led to more weight loss overall.

The researchers argue fat loss was more important to the obese people in this study for long-term weight loss. This implies the weight loss achieved in the low-carb diet was not down to fat loss. Although this wasn't stated in the study, you can lose weight via losses in muscle and water.

Both the BBC and the Mail carry a useful quote from an independent expert, Professor Susan Jebb, who rightly says: "The best diet for weight loss is the diet you can stick to". So outside of the highly restricted diet lab, the bigger issue of weight loss is how to stick to a diet in the long term.  

What kind of research was this?

This human laboratory study looked at the way two short-term diets – one low in fat, one low in carbohydrates – affected a person's metabolism and any weight loss.

Your body gets energy from two main sources: by burning fat and carbohydrate. Both are regulated by the hormone insulin. Popular weight-loss diets often advise cutting down either fat or carbohydrates, but there is debate about which works best.

This study wasn't focused on weight loss, but was geared up to investigate how diet influences how the body burns fat and carbohydrate. The researchers highlighted past randomised control trials showing greater short-term weight loss in obese patients on low-carb diets.

But they say there are problems with these studies, meaning we don't know if they help you lose weight by changing your metabolism for the better – lowering insulin levels and causing more fat burning and energy expended as a whole – or simply make you eat less overall.

Low-carb diets can be higher in protein and fat, which are filling, making you eat less. This wasn't the case in this study. 

What did the research involve?

The study confined 19 obese adults (9 men, 10 women) to a "metabolic ward", or diet lab, for two two-week periods while on low-fat or low-carb diets. While in the diet labs, researchers meticulously monitored and restricted their diets, energy intake and expenditure, and used a host of biological measures to establish whether they were burning fat or carbohydrates as their source of energy.

Each person spent five days in the diet lab on an energy-balanced diet (50% carbohydrate, 35% fat, 15% protein) before being randomly assigned to a diet that slashed their calorie intake by 30% (around 800 calories a day lower) for a further six days. This was achieved either through a 60% reduction in carbs (low-carb diet) or an 85% reduction in fat (low-fat diet).

Throughout the six days they had no access to additional food or drink, and even meetings with visitors were watched by nurses or researchers to catch any potential cheating.

After a two- to four-week washout period where they could eat what they liked, volunteers were readmitted to try the other diet. This repeated the five-day balanced diet followed by the alternate six-day low-fat or low-carb diet.

Some physical activity was controlled – they all had to do 60 minutes of walking on a treadmill each day – and the rest was monitored using portable activity monitors worn on the hip.

The study excluded those who had large weight change (more than 5kg) in the past six months, had diabetes, were menopausal, were pregnant or breastfeeding, or had mobility problems.

Two men dropped out of the study after the first stint on the low-carb diet, so did not contribute data to the subsequent low-fat diet part of the study.  

What were the basic results?

Both diets led to weight loss over the six days, but those on the low-carb diet lost significantly more. After six days the low-carb group had lost about 1.85kg on average compared with around 1.3kg on the low-fat diet, around a half kilo difference in just six days.

The low-carb diet led to significant changes in metabolic fuel selection. Insulin levels dropped, which lowered carbohydrate burning by around 500 calories a day and increased fat burning by around 400 calories a day. "Remarkably", as the researchers put it, fat burning didn't change fuel selection – both fat and carb burning remained unchanged.

That said, the low-fat diet resulted in a greater body fat loss compared with the low-carb diet, despite being equivalent in calories. Short-term fat loss was measured as the difference between the amount of fat taken in and the amount of fat burnt (as measured by biological testing) in the diet lab – this isn't the usual way.

The normal measurements, percentage body fat or fat mass, didn't change between the groups. The authors used the short-term measure because the study was too short to influence body fat percentage or fat mass.

The team built a mathematical model to predict changes in metabolism and body weight before the study was conducted. They adapted the model using the data collected and predicted what would happen in the future. The model accurately predicted the results of the short-term diets and predicted small long-term differences in body fat.  

How did the researchers interpret the results?

The researchers say that, "Calorie for calorie, restriction of dietary fat led to greater body fat loss than restriction of dietary carbohydrate in adults with obesity. This occurred despite the fact that only the carbohydrate-restricted diet led to decreased insulin secretion and a substantial sustained increase in net fat oxidation compared to the baseline energy-balanced diet."

They added: "We can definitively reject the claim that carbohydrate restriction is required for body fat loss", saying that, "Fat loss is a more important goal than weight loss in the treatment of obesity" and that outside of the highly controlled diet lab "diet adherence is likely the most important determinant of body fat loss". 


This well-designed diet lab study showed that a six-day low-carbohydrate diet affects a person's metabolism far more than a low-fat diet. The low-carb diet led to more fat burning and overall energy expenditure via lower insulin levels, whereas the low-fat diet didn't alter fat or carb-burning proportions, but led to more fat loss.

The study was well designed and rigorous, but included only 19 people and lasted only a few weeks. This is a small number of people, and a short amount of time, on which to base any generalisations about most people. The results aren't convincing enough to settle the low-carb versus low-fat diet debate.

The diets were pretty extreme and rigorously enforced under diet lab supervision. Sticking to a diet that cuts energy intake by a third, including fat intake by 85%, would be a big challenge for people outside of the diet lab.

But these large changes were necessary to elicit a measureable effect in the short time the researchers had available – they weren't meant to be directly applicable to outside life. Smaller changes over the long term might work equally well, something the researchers' mathematical modelling attempted to predict. 

The researchers did make the point that the low-carb diet they were investigating wasn't a low-carb diet in the traditional sense. They kept carbs at 140g a day, when traditional low-carb diets are said to contain less than 50g per day.

But to do this they would have had to increase fat and protein intake to balance out calorie intake, which they didn't want to do as they wanted to look at the sole effect of reducing carbs.

This again highlights that making overall conclusions on the effects of low-fat or low-carb diets in general is not possible outside the strictly controlled and specific dietary composition used in this study. 

Professor Susan Jebb, Professor of Diet and Population Health at the University of Oxford, hits the nail on the head, saying: "The real challenge for science is not the nutritional composition of the diet, but the behavioural strategies to promote adherence.

"All diets 'work' if you stick to an eating plan that cuts calories, whether from fat or carbohydrate, but sticking to a diet is easier said than done, especially given the prolonged time it takes to lose weight."

Starchy foods high in carbohydrate should make up around one-third of everything we eat. This means we should base our meals on these foods. Read more about a balanced diet.

Want to lose weight without resorting to gimmicks? The NHS has a tried-and-tested weight loss plan.

Links To The Headlines

Low-fat diets 'better than cutting carbs' for weight loss. BBC News, August 14 2015

STILL the great diet debate rages: Low-carb 'is best for weight loss but forsaking fat is BETTER for your health', latest study reveals. Daily Mail, August 14 2015

Cutting fat from your diet 'is BETTER for losing weight than cutting carbs'. Daily Mirror, August 14 2015

Links To Science

Hall KD, Bemis T, Brychta R, et al. Calorie for Calorie, Dietary Fat Restriction Results in More Body Fat Loss than Carbohydrate Restriction in People with Obesity. Cell Metabolism. Published online August 13 2015

Categories: NHS Choices

Music can help ease pain and anxiety after surgery

NHS Choices - Behind the Headlines - Thu, 13/08/2015 - 12:30

"Listening to music before, during and after an operation can help reduce pain," BBC News reports. An analysis of data found evidence that people who listened to music had reduced anxiety and were less likely to request pain relief.

Listening to music during a surgical procedure is a very different thing, and it is important to note that this is not routine practice in the NHS. You would not normally expect to be able to choose to have music played to you while unconscious under a general anaesthetic, for example. But for procedures performed while you are awake under local or spinal anaesthesia this could be possible.

Researchers say that following up this work, the Royal London Hospital is conducting an experiment where about 40 women having either a caesarean section or another gynaecological procedure will be given the chance to have their playlist connected to a pillow with in-built speakers.

There are no known negative effects of listening to music, and you would be expected to be free to listen to personal music before a surgical procedure (for example while waiting to be taken to the operating theatre) or when recovering on the ward after. And if you find music helps you relax in these situations, it must be a good thing.

If you are having an operation in the near future you may want to start putting a playlist together. We recommend something soothing – Mozart as opposed to Motörhead.


Where did the story come from?

The study was carried out by researchers from Queen Mary University, Barts Health NHS Trust and Brunel University, all in London. Researchers say that this study received no funding from any organisation.

The study was published in the peer-reviewed medical journal The Lancet.

Several UK media sources have covered this story. Overall, media reported the results accurately. However, some of the limitations of the study are not fully explained.

BBC News reported a quote from one of the lead authors of this study, Dr Catherine Meads, who said that listening to Pink Floyd's Dark Side of the Moon album helped soothe her pain three hours after hip surgery in April 2015. She says, "music was a safe, cheap and non-invasive option that should be available to everyone having surgery".

She added: "Currently music is not used routinely during surgery to help patients in their postoperative recovery. The lack of uptake is often down to the scepticism of professionals as to whether it genuinely works, and of course issues of budget and the integration into daily practice."

The Daily Mirror also provides some song suggestions of its own, including Smooth Operator by Sade, Getting Better by The Beatles and The First Cut is the Deepest by Rod Stewart.


What kind of research was this?

This was a systematic review and meta-analysis that aimed to assess the effects of music before, during or after surgery in reducing pain and anxiety in postoperative patients.

Researchers say that music was first found to be helpful in patients during operations in 1914 and since then several studies have investigated the effects of music on emotions, pain and sensation.

There are even reports of Florence Nightingale using music to improve her patients' morale.

Systematic reviews gather all published evidence on a particular topic. Meta-analysis is a statistical method that pools the data from many studies to find an overall result. This increases the reliability of the results. It is important to note that this type of research methodology relies on findings from previously published studies, so the reliability of the results depends on the quality of the studies included in the analysis. In this case the differences in study methods and included populations are a potential limitation. 


What did the research involve?

Researchers pooled data from 73 randomised controlled trials (RCTs) (total of 6,902 patients) that looked at the effects of music in adult patients undergoing any form of surgical procedure (with or without sedation or anaesthesia). This could be any form of music initiated before, during or after surgery.

Relevant outcomes examined were:

  • postoperative pain
  • need for painkillers (analgesia)
  • anxiety
  • infection rates
  • wound healing
  • costs
  • length of stay
  • satisfaction with care

These studies used comparators such as standard care and other non-drug interventions (e.g. massage, undisturbed rest, or relaxation).

To avoid selection bias two investigators independently checked the eligibility of the studies for inclusion and any differences were resolved through discussions and referral to a senior investigator. The quality of each study was assessed using a standardised checklist. They also conducted sub-group analysis to assess the effects of factors such as timing of music (before, during or after), type of anaesthesia, type of control comparison, and choice of music.

The included studies had a sample size ranging from 20 to 458 participants who had undergone surgical procedures ranging from minor endoscopic (camera) interventions to transplant surgery. In the included studies either the researcher or the patient themselves chose the type of music. Types of music covered by the studies were classical music, instrumental, relaxing, or patient's choice music. Duration of the music varied from a few minutes to repeated episodes for several days.

Pain was generally measured using a Visual Analogue Scale (VAS) or Numerical Rating Scale (NRS). These scales are used to measure subjective characteristics or attitudes that cannot be directly measured (such as pain) – e.g. "on a scale of 1 to 10, with 1 equalling no pain and 10 equalling intolerable pain, how much pain are you in?" These pain scales are mostly self-reported and sometimes observed by others.


What were the basic results?

Overall, the review found that music reduced postoperative pain in adults.

Details are as follows:

  • the pooled results of 45 RCTs show that music reduced postoperative pain with standardised mean difference (SMD) on the pain scale -0.77 (95% confidence interval (CI) -0.99 to -0.56)
  • 43 RCT studies found reduction in postoperative anxiety (SMD -0.68, 95% CI -0.95 to -0.41)
  • 34 RCT studies found reduction in postoperative painkiller use (SMD -0.37, 95% CI -0.54 to -0.20)
  • 16 studies found increased patient satisfaction with music (SMD 1.09, 95% CI 0.51 to 1.68)

The sub-group analysis found that no other factors (such as choice and timing of music, type of anaesthesia, pain measure used, etc.) had a significant influence on the effect of music on pain.


How did the researchers interpret the results?

Researchers conclude: "Music is a non-invasive, safe, and inexpensive intervention that can be delivered easily and successfully in a hospital setting. We believe that sufficient research has been done to show that music should be available to all patients undergoing operative procedures."

They add: "Timing of music does not make much difference to outcomes so can be adapted to the individual clinical setting and medical team."



This systematic study with meta-analysis found that use of music around the time of surgery reduced postoperative pain, anxiety and use of painkillers in an adult population.

This study has several strengths including that it has captured studies published in all languages, which reduces selection bias. It also helps in generalising the results. It has also made careful assessment of the eligibility and quality of the studies to help reduce selection bias.

The review included a large number of studies and the overall participant sample size was large. However, one of the main limitations is that the majority of the individual RCTs had small sample sizes, except for one (458 participants).

The individual trials also varied considerably in their methods, including the study populations, type of surgical procedure and anaesthetic given, and the timing and type of music. A strength of the findings though, is that the researchers conducted sub-group analyses to see if any such factors could have had a significant influence on the effect of music and found none.

Another point worth noting is that the average difference on the pain and anxiety scales between the music and control groups was fairly small (less than 1 point). It is not known how much of a meaningful clinical effect on the person's wellbeing and experience of surgery these would have.

A large and well-conducted RCT in the future could help strengthen the findings of this review, and also better inform whether there are particular circumstances (e.g. type of procedure or anaesthetic) in which music can be beneficial.

Other self-help methods you can use to relieve – or at least distract yourself – from pain include activities such as knitting or sewing, breathing exercises, reading an engaging book, or playing games on your phone or tablet. Read more self-help tips about easing pain.

Links To The Headlines

Music 'reduces pain and anxiety' for surgery patients. BBC News, August 13 2015

Listening to music before and after surgery relieves pain and anxiety. The Daily Telegraph, August 13 2015

How music could help beat pain of surgery: Listening before, during or after an operation can reduce pain afterwards and leave patients feeling happier. Daily Mail. August 13 2015

Music helps patients recover more quickly if played before surgery. Daily Mirror, August 13 2015

Links To Science

Hole J, Hirsch M, Ball E, Meads C. Music as an aid for postoperative recovery in adults: a systematic review and meta-analysis. The Lancet. Published online August 12 2015

Categories: NHS Choices

Checking emails out of work 'can reduce wellbeing'

NHS Choices - Behind the Headlines - Wed, 12/08/2015 - 15:00

"Checking your emails outside of work really IS bad for your health," the Mail Online reports. A German study recruited a sample of 132 workers and aimed to look at how extended working outside normal hours influenced people's mood the next day.

It found working outside normal working hours limits the sense of detachment from work, and these factors are linked to feeling more tired and less relaxed and content the next day. It was also linked to higher morning levels of the stress hormone cortisol.

This issue is very relevant to today's working culture, where remote working and smartphones allow many of us to be continually engaged with work outside normal working hours.

However, the study gives limited representation of UK workers in general. It assessed the effect of formal "on-call" duties, compared with days when people didn't have these duties. This means it isn't as relevant as it first appears to be for the many UK workers who don't have formal arrangements like this, but who do respond to emails and calls at home outside normal working hours.

If you are not contractually obliged to respond to emails or phone calls outside your normal working hours, we recommend you don't. Creating a clear split between your working life and home life could make you less stressed and, ultimately, improve your performance at work.  

Where did the story come from?

The study was carried out by researchers from the University of Hamburg and supported by the German Federal Ministry of Education and Research.

It was published in the peer-reviewed Journal of Occupational Health Psychology.

The Mail's coverage implies the findings apply to all workers, when in fact the study was focused on formal on-call arrangements. The effects of being officially on-call may be different from more informal out-of-hours work, such as checking emails on your smartphone in the evening.   

What kind of research was this?

This was an experimental study exploring the relationship between the extended availability of employees outside work hours and the physical and psychological effect this can have on the body by looking at mood and stress hormones.

The researchers discuss today's mobile technology environment of smartphones and easy access to the internet, and remote communication with co-workers and customers at any time and place.

Previous studies observed how this technical opportunity to continue working outside normal hours and beyond the normal workplace has led to larger workloads and greater employer expectations. It also intrudes on home and family life, crossing the "work-family border".

The researchers define extended work availability as "a condition in which employees formally have off-job time, but are flexibly accessible to supervisors, co-workers or customers, and are explicitly or implicitly required to respond to work requests". The expectation is that recovery from work is limited under such conditions and this may impair wellbeing.

Three main hypotheses were investigated by this study:

  • extended work availability the previous day has negative effects on mood at the start of the following day, and is associated with higher levels of the stress hormone cortisol when waking up
  • extended work availability has negative effects on psychological detachment on the same day and limits control over out-of-work activities
  • the effect extended work availability has on mood at the start of the next day is influenced by the amount of psychological detachment the previous evening and how much control the person felt they had over out-of-work activities
What did the researchers do?

The study recruited 132 participants from 13 organisations. Participants were 91% male with an average age of 42 years, and the majority had worked at the same organisation for more than five years. The organisations were involved in transport and logistics, water supply, IT and technical services, trade, nurseries and hospitals.

The participants completed daily surveys during four days when they were on on-call duty (defined as being expected to be available during non-working hours) and four days when they were not on call. These were both composed of two weekday and two weekend days.

Participants completed the surveys using handheld computers that had an alarm to prompt them to complete them at set times of the day – for example, the start of the day and the afternoon.

The surveys contained questions on work and covered components from different psychological assessment scales. For example, to assess extended availability they would be asked, "How many calls from work did you receive in the last 24 hours?".

Recovery would be assessed using a scale where participants had to assess how much they agreed with statements such as, "This evening, I didn't think about work at all".

Mood at the start of the day was assessed by choosing from options such as, "At this moment, I feel discontent/content and unwell/well (valence), tired/awake and without energy/full of energy (energetic arousal), agitated/calm and tense/relaxed (calmness)."

A sub-sample of 51 participants gave consent to provide saliva samples so cortisol levels could be measured. Cortisol is a hormone the body releases in response to stress.

The researchers were mainly examining the effects of on-call duties for individuals, rather than between individuals. Potential confounding factors adjusted for in the analyses were age, gender, normal working hours, and the day of the week of the assessment. Cortisol measures were also adjusted for individual factors such as body mass index (BMI), smoking status, and subjective physical and mental health. 

What were the basic results?

In support of the researchers' first hypothesis, the results suggested extended work availability had negative effects on the three core mood components the following morning: energetic arousal, calmness and valence. It also increased cortisol levels the next morning.

In support of the second hypothesis, there was also a negative effect of extended work availability on recovery from work – that is, feeling detached from work and having a sense of control over one's out-of-work activities.

Lastly, they found the amount of recovery a person felt mediated the effect extended working hours had on their mood the next day. However, recovery experiences of control and detachment did not mitigate the effect extended working hours had on cortisol levels.  

How did the researchers interpret the results?

The researchers concluded that their study "provides evidence that extended work availability during non-work hours negatively affects employee wellbeing and recovery".

By this, they mean being expected to respond to work issues outside work restricts employees' crucial leisure time, which allows them to recover from work.  


This study explored the effects of extended working hours on an individual's mood and cortisol levels the next day. Perhaps unsurprisingly, it found working outside normal working hours limits a person's sense of detachment from work, and these factors are linked to feeling more tired and less relaxed and content the next day. The study will be of interest to sociologists, psychologists and the general public – being very relevant to today's 24/7 working culture.

However, a key limitation of this study is whether its findings apply to workers in the UK in general. The study involved a fairly small sample of predominantly male middle-aged workers, who will not be representative of the general UK population.

They had all responded to an advertisement saying this was a study aiming to optimise on-call work. It is possible the people who are most impacted by extended working hours may not respond to such an advertisement, as they may have thought they were too busy or had no time to take part in a study on top of all their other commitments.

This study looked at the impact of formal on-call days, when people were expected to be available during non-working hours, compared with days without this requirement. The formal on-call duty may be applicable in some professions – hospital workers, for example – but is this really representative of the general work culture the study aimed to assess? 

We live in an environment centred in mobile technology, where people have continued access to colleagues, clients and work projects. Many professionals won't have formal "on-call" days, but they may be in an environment where every working day has the potential to encroach on what should be their out-of-work recovery time. This environment of non-formal extended working hours – through emails, calls, at-home working, etc – may have an even greater effect on general health and wellbeing.

Even for this specific sample, the study's results may not be concrete. The study used surveys making use of valid psychological assessment scales, but these may not be able to capture all of the person's thoughts and feelings and other factors that may be involved beyond just the influence of working hours.

Also, the researchers only assessed this on a sample of days within a two-week period, which may not necessarily be representative of long-term working patterns.

What's more, this study was conducted in Germany, which may have a different work culture and environment from other countries.

Overall, the study is undoubtedly of topical interest, but because of the limitations of its small sample size, it can't provide definitive answers.

Most occupational psychologists would agree with the principle that you need to create a clear divide between your work life and your home and family life. If you are not on call, try to resist the temptation to check your work emails in the evening, or even worse, on holiday.

Links To The Headlines

Checking your emails outside of work really IS bad for your health, 'increasing stress levels and reducing wellbeing'. Mail Online, August 11 2015

Links To Science

Dettmers J, Vahle-Hinz T, Bamberg E, et al. Extended Work Availability and Its Relation With Start-of-Day Mood and Cortisol. Journal of Occupational Health Psychology. Published online August 3 2015

Categories: NHS Choices

Claims that 'butter is safe' and 'margarine deadly' are simplistic

NHS Choices - Behind the Headlines - Wed, 12/08/2015 - 13:25

"Butter unlikely to harm health, but margarine could be deadly," The Daily Telegraph reports. A major analysis of data found no link between saturated fats and heart disease, stroke or diabetes, but there was a link with trans fats.

Saturated fats are found in dairy products such as butter and cheese, as well as in meat and some fish, such as salmon. Some trans fats may come from natural animal sources, but most are from changes made to plant oils during the industrial manufacturing process.

This latest research, which pools the results of around 70 previous studies, found no evidence that eating higher amounts of saturated fat (compared to low amounts) raised the risk of death, heart disease, stroke or diabetes. Meanwhile, eating more trans fats was linked to an increased risk of death or heart disease.

However, the researchers warned that the results are not clear-cut and future research could change the picture. These were all observational studies, which cannot prove cause and effect. Consuming high levels of saturated fat can increase the risk of obesity – a condition that can adversely impact on quality of life.

The researchers make the important point that, rather than focusing on a single food source, a person's whole diet is important. They say that any future guidelines about healthy diets that recommend reducing fat need to be clear about what people should eat as an alternative.


Where did the story come from?

The study was carried out by researchers at McMaster University, the University of Toronto, St Michael's Hospital Toronto, Hamilton Health Sciences, and the Hospital for Sick Children Toronto, all in Canada. It was funded by the World Health Organization. It was published in the peer-reviewed medical journal The BMJ, as an open-access article, which means anyone can read it for free online.

The study was reported accurately in The Independent, which included the researchers’ warnings about the study’s limitations. The Daily Mirror concentrated on the risks from trans fats, while the Telegraph accompanied its article with encouragement to eat more butter – a recommendation not backed by the current available evidence.

The Daily Express’s warning that "low fat versions [of spread] could kill you" is just plain daft.

Much of the tone of the reporting seems out of date, as many sources seemed to imply that margarine contained high levels of trans fats. In fact, due to the negative publicity surrounding trans fats in recent years, food manufactures have virtually removed trans fats from the UK food chain.

Most brands of margarine now contain no, or only trace elements, of trans fats.

recent factsheet released by the British Nutrition Foundation (PDF, 23kb) estimated that, on average, trans fats account for 1% of total energy intake per person in the UK, which is thought to be well within safe limits.


What kind of research was this?

The researchers carried out a systematic review of observational studies about saturated fat and trans fats, and health outcomes. They performed a meta-analysis by pooling the best-quality studies to see what the results showed overall.

A systematic review and meta-analysis is an excellent way of summing up the state of research on a topic at any given time. However, the results are only as good as the existing studies on the topic. Observational studies can show links between things (in this case, saturated fat and health outcomes such as chances of death) but cannot prove that one thing causes another.


What did the research involve?

The researchers searched databases to find all the research done so far on this topic. They pooled the results of prospective cohort studies in a meta-analysis. One big prospective cohort study on saturated fat could not be pooled because of the way the data was presented, but the researchers compared it to the results of the meta-analysis, to see if the results agreed. They also looked at the results of other studies with different designs. They aimed to see whether there was a link between eating more or less saturated fat or trans fats and outcomes, including death from any cause, heart disease, stroke and type 2 diabetes, and deaths from these specific causes.

In most of the studies included, the researchers compared what happened to the people who ate the most of the type of fat being studied, compared to the least. This means that the amount of fat eaten could vary a lot between studies. Most of the studies measured how much fat people ate by asking them to fill in a questionnaire about how much of different types of food they had eaten in the last day, week or month.


What were the basic results?

The researchers found no link between eating more saturated fat and the chances of dying from any cause, dying from cardiovascular disease (heart disease or stroke) or heart disease specifically, or getting heart disease, stroke or type 2 diabetes.

They found evidence that eating more trans fats increased the chances of dying from any cause (relative risk (RR) 1.34, 95% confidence interval (CI) 1.16 to 1.56), dying from heart disease (RR 1.28, 95% CI 1.09 to 1.5) and having heart disease (1.21, 95% CI 1.1 to 1.33).

They then checked the studies and their findings against a quality system called GRADE (Grading of Recommendations Assessment, Development and Evaluation), to see how reliable the results are likely to be. The system found that the certainty of the results was likely to be very low for saturated fat. That is, that while no link was found between saturated fat intake and these findings, we can’t have much confidence in this finding. However, it was moderate for the link between trans fats and heart disease or death from heart disease, suggesting there is stronger evidence for this link.


How did the researchers interpret the results?

The researchers were cautious about their results (unlike the media). They said that "further research is likely to have an important effect on our confidence in the estimation of association and could change the estimate." This means that, because of the limitations of the research published so far, better research in the future might give a different answer to the question about whether saturated fat is bad for our health.



This careful systematic review and meta-analysis of research into the effects of saturated and trans fat on health found no evidence that eating more saturated fat raises the risk of death from any cause, death from cardiovascular disease, or risk of getting heart disease, stroke, or type 2 diabetes. However, the authors say they can only have "very low" confidence in their findings, because of the methodological limitations of the individual studies that contributed data.

The study did find a link between eating more trans fats and death from any cause, from heart disease or risk of getting heart disease. In the study, trans fats from industrial sources (rather than natural animal sources) were more strongly linked to heart disease or the chances of dying from heart disease. However, this may just be because people in the studies had eaten more industrial trans fats than natural trans fats.

The researchers say they only have low confidence in their findings for several reasons. A meta-analysis is only as good as the studies that you can include in it. The included studies had considerable differences in their methods and results. The researchers could not include one big study because the way that the data had been collected and analysed made it impossible to pool with the other studies in the meta-analysis. The meta-analysis results showed no link between saturated fat and risk of death, while the big study they could not include showed that eating more saturated fat was linked to an increased risk of death. We don't know whether including the results of this study would have changed the overall results of the meta-analysis, if that had been possible.

There could be various reasons for the differences in findings between the different studies. They might have included different study populations, or varied in how they recorded their diet or assessed and followed up the health outcomes. The studies are also likely to vary in how well they took account of different confounding factors that might have affected the results (for example, people's age, occupation, total food consumption, exercise, smoking, income). The problem with studies looking at one part of people’s diets (in this case, saturated fat or trans fat) is that the rest of their lifestyle may also have a big impact on their health.

Finally, the researchers make an important point about what people are eating instead of saturated fat. Refined carbohydrates such as white bread and sugar may be no healthier than fat. And we don't know whether some other types of fats, such as monounsaturated fat, are healthier than saturated fat. This is especially important for people setting national guidelines about diet. If guidelines tell people to eat less saturated fat, or less trans fats, they should also say what people should eat instead, if they are to have a positive effect on health.

While this study does not show strong evidence that saturated fat is harmful, it does not rule out the possibility that it may be harmful.

It cannot be concluded that people can eat as much saturated fat as they like, without any effect on their health.  

Links To The Headlines

Butter unlikely to harm health, but margarine could be deadly. The Daily Telegraph, August 11 2015

'No link' between eating fatty food and early death: Findings raise further doubts over advice to avoid butter, full-fat milk and other meat and dairy products. Daily Mail, August 12 2015

Saturated fats in meat and dairy may not be as bad for you as once thought, but I'd still stick to fresh fruit and wine. The Independent, August 11 2015

Trans fats used to extend processed food's shelf life 'can significantly increase risk of death'. Daily Mirror, August 11 2015

Now it's OK to eat FAT: Normal milk and butter safe but low fat versions could KILL YOU. Daily Express, August 12 2015

Links To Science

de Souza RJ, Mente A, Maroleanu A, et al. Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies. BMJ. Published online August 12 2015

Categories: NHS Choices

Does red meat affect male fertility?

NHS Choices - Behind the Headlines - Tue, 11/08/2015 - 13:30

"Want to be a dad? Cut out sausages and eat chicken," the Daily Mail reports, prompted by the findings of a recent study into diet and fertility outcomes for couples undergoing fertility treatment.

This study analysed the diets of 141 men attending a fertility clinic with their partners for help getting pregnant. Sperm from men who reported a diet high in processed meat had less success fertilising eggs in the laboratory. But sperm from men who ate more chicken were more successful.

Crucially, however, none of these variations in diet affected the chance of the couples becoming pregnant after treatment, or having a baby. This means the study cannot prove that processed meat causes lower male fertility or that chicken boosts it. These associations could be valid, but there might also be other factors involved. And men who choose to avoid eating processed meat may also be healthy in other ways.

That said, eating a healthy, balanced diet low in processed meat certainly can't hurt in terms of boosting male fertility. Other methods include quitting smoking if you smoke, moderating your consumption of alcohol, and avoiding things that warm up your testicles, such as wearing tight underwear or having hot showers or baths, all of which can affect sperm production

Where did the story come from?

The study was carried out by researchers from Harvard Medical School and Massachusetts General Hospital in the US, and Huazhong University of Science and Technology in China. It was funded by the US National Institutes for Health and the China Scholarship Council.

The study was published in the peer-reviewed medical journal Fertility and Sterility.

The Daily Mail's reporting of the study was of a high standard, signalling an appropriate note of caution: "Because the scientists looked only at statistics and did no health or lifestyle tests, they cannot draw any firm conclusions as to cause and effect. But they suspect the levels of fat and chemicals in processed meat may be significant."

The Mail provided the sound advice that, "Experts advised couples undergoing fertility treatment to eat a healthy diet." The article also included useful commentary from an independent expert, Allan Pacey, professor of Andrology at the University of Sheffield, who said: "I would be concerned that eating poultry is just a surrogate marker for some other aspect of a man's life which has not been measured here." 

What kind of research was this?

This prospective cohort study looked at the effect of the male partner eating meat on a couple's success during fertility treatment.

Infertility is a common problem. Around one in seven couples may have difficulty conceiving, which is around 3.5 million people in the UK. It is usually advised you seek advice for potential infertility problems if you and your partner are unable to conceive after one year of trying.

Fertility treatments are also called assisted reproductive technology (ART). There are various options that may be considered, depending on the likely cause of the couple's fertility problems.

These include medications to help the woman release eggs, in vitro fertilisation (IVF), where the sperm and eggs are cultured in the laboratory and the embryo is then implanted, and intracytoplasmic sperm injection (ICSI), where a single sperm is injected directly into the egg.

Following a healthy lifestyle and maintaining a healthy weight through physical activity and a balanced diet, not smoking or using other substances, and moderating alcohol intake may also help boost the chances of conceiving.

The researchers say the possible impact of the man's diet on fertility has had a lot of attention recently, particularly the role of meat intake, which may influence sperm development. This was the focus of their new study.

This type of study can't prove cause and effect, as the couple were already having fertility problems at the time the male diet was assessed and many other factors could be involved. A randomised control trial, randomly allocating diets differing in meat intake, would be required for this.

However, there would likely be several ethical issues of randomising a man attending a fertility clinic to high or low meat intakes to see if this had an effect. For example, there could be a possible time delay for any effects and the known adverse health effects of a high-meat diet, such as an increased risk of bowel cancer. 

What did the research involve?

The research gathered dietary information from 141 men whose partners were having fertility treatment to help them conceive between 2007 and 2014. All of the couples in this study were receiving IVF or ICSI. The amount and type of meat intake by the male partner was estimated from dietary questionnaires.

They wanted to see if the amount and type of meat affected fertility success, which was defined in a number of ways:

  • fertilisation rate – the proportion of female eggs successfully fertilised by male sperm in the laboratory
  • implantation rate – the percentage of embryos successfully implanted into the women's womb
  • pregnancy rate – the percentage of fertility cycles (attempts) leading to a pregnancy
  • live birth rate – the percentage of fertility cycles leading to a live birth

The analysis took account of factors (confounders) known to affect fertility in addition to meat intake, including:

  • total energy intake
  • age
  • body mass index
  • alcohol
  • caffeine
  • prudent dietary pattern – a diet high in fruit, vegetables, wholegrain foods, poultry and fish
  • western dietary pattern – a diet high in red and processed meat, sugary desserts, high-fat foods and refined grains

Taking account of these factors helps isolate the individual effect of eating meat against everything else. 

What were the basic results?

Processed meat was linked to lower fertilisation rates, whereas eating more chicken was linked to higher fertilisation rates.

Men's total meat intake, including their intake of specific types of meat, was not associated with implantation, pregnancy or live birth rates.

There was a 13% higher fertilisation rate in men in the highest quarter of poultry intake compared with those in the lowest quarter (78% versus 65%).

Processed meat intake was inversely related to fertilisation rate in couples having conventional IVF – that is, as processed meat intake went up, the fertilisation rate went down.

The fertilisation rates for men in increasing quarters of processed meat intake were 82% (lowest quarter of processed meat intake), 67%, 70% and 54% (highest processed meat intake) in conventional IVF cycles.

Processed meat intake was not associated with fertilisation rate in couples receiving ICSI.  

How did the researchers interpret the results?

The authors concluded that, "Our study expands the growing literature regarding the relationship between diet and markers of male fertility.

"However, owing to the scarcity of data on how men's diets in general and meat intake in particular influence infertility treatment outcomes, further research is needed to clarify these relations to allow the formulation of clinically relevant recommendations in the future." 


This study of a cohort of men attending a fertility clinic for help to conceive found fertilisation rates in the laboratory during IVF were less successful if men reported a diet high in processed meat, and more successful if they ate more chicken.

Importantly, the effect of overall meat intake was not related to fertility success, which is the chance of becoming pregnant after the treatment cycles, or having a live birth.

It was also not clear whether the variation in fertility rate influenced how many cycles of IVF were needed, or how long the couple needed medical assistance, before they became pregnant or had a child. If more IVF cycles were needed, this would be more expensive, especially if people are paying for private fertility treatment.

So what does this mixed bag of results tell us? It does not tell us processed meat causes lower fertility or chicken boosts it. That could be true, but there could be lots of reasons why the individual couples at the fertility clinic had difficulty conceiving – not all related to male fertility.

Also, the amount of processed meat men eat could be a marker of how generally healthy their diet is, or how healthy they are in general, both of which may influence sperm development and fertility. The researchers did attempt to account for this in their analysis, but this might not completely eliminate the effects. Other relevant factors, such as smoking, have not been taken into account.

The researchers say they previously found a link between meat intake and changes in sperm shape in sub-fertile men attending a fertility clinic. This gives a potential biological mechanism explaining how meat might be linked to fertility, but again it might not necessarily be because of meat – it could be the wider diet, or something else entirely.

The results are relevant to couples receiving fertility treatment. However, they are not directly relevant for people conceiving without medical assistance. In fact, a useful exercise would be to compare the diets of men from couples needing fertility assistance with those who got pregnant naturally.

Though the theory of meat intake influencing sperm development is plausible, for all we know these men may be eating much less meat than those who have had no trouble conceiving naturally.  

The study is consistent with current advice to follow a healthy, balanced diet. Though this study does not prove a high intake of processed meat reduces male fertility, it has been linked to other adverse health risks – notably bowel cancer.

Read more about healthy eating.

Links To The Headlines

Want to be a dad? Cut out sausages and eat chicken: Men who eat high level of processed meat up to a third less likely to become a father. Daily Mail, August 10 2015

Links To Science

Xia W, Chiu Y, Williams PL, et al. Men's meat intake and treatment outcomes among couples undergoing assisted reproduction. Fertility and Sterility. Published online July 20 2015

Categories: NHS Choices