"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.
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:
- health conditions, including high blood pressure, diabetes, coronary artery disease, stroke and heart attack
- cholesterol levels
- body mass index (BMI)
- 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.
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
"Terrible twos?" asks the Mail Online, going on to say that, "the bacteria in your child's gut may be to blame for their bad behaviour". The story is based on research that showed links between the types of bacteria in stool samples from two-year-old children, and their behaviour and temperament.
Researchers have become increasingly interested in how the population of bacteria in the gut (known as gut microbiota) affects health.
Studies have already linked gut bacteria to conditions including obesity, allergies and bowel disease. Now researchers are interested in finding out if gut bacteria is also linked to mental health – for example, depression and anxiety.
So they took stool samples from 75 children in Ohio in the US, and their mothers filled in questionnaires about their temperament and behaviour. They wanted to see whether aspects of a child's temperament were linked to the bacteria in the gut.
The researchers found that both boys and girls who had greater diversity of bacteria in their gut were likely to have higher scores for "surgency" – a term used to describe a combination of impulsive behaviour and high levels of activity.
While the study found a link, it is impossible to say whether the bacteria actually caused the behaviour, or whether other factors are responsible for the link seen. This is very early exploratory research, so we can't draw too many conclusions from it.
And we certainly wouldn't advise trying to alter your toddler's gut microbiota to improve their behaviour. Just stick to a few minutes on the naughty step.Where did the story come from?
The study was carried out by researchers from Ohio State University in the US and was funded by grants from the university and the National Institutes for Health, and the National Center for Advancing Translational Sciences. It is published in the peer-reviewed medical journal Brain, Behavior and Immunity.
The Mail Online ignored warnings in the study that it cannot show whether bacteria causes differences in temperament or behaviour, claiming that it showed how "abundance and diversity of certain bacteria can impact a child's mood", and that parents should "blame the bacteria" in the child's gut if their toddler is "acting up".
The study did not look at "acting up" or bad behaviour, but at temperament scales, which included how extrovert and physically active a child is.What kind of research was this?
This was a cross-sectional study. It aimed to see whether gut microbiota (the range and amount of bacteria living in the gut) were linked to a child's temperament.
Cross-sectional studies cannot determine which factor came first – in this case, whether the differences in bacteria were present before the children developed a particular temperament. This means they cannot say which factor might potentially be influencing the other.
In addition, observational studies such as this can't show whether one thing definitely causes another, just whether the two happen to be linked in some way. Much more evidence, from a range of different studies and study designs, is needed before scientists are happy to conclude that one thing is likely to cause the other.What did the research involve?
Researchers sent online questionnaires to 79 mothers who volunteered for the study to assess their child's temperament, diet and feeding behaviour. Children were all aged 18 to 27 months.
The mothers then collected stool samples from the babies' nappies, which were sent to the researchers for analysis. The researchers used statistical modelling to work out whether the diversity of bacteria or the abundance of any types of bacteria were linked to particular types of temperament.
Of the 79 children tested, only 75 were included in the final analysis. In two cases the stool samples could not be analysed; the reasons for exclusion of the other two were not clear, but may relate to questionnaires showing results outside the usual expected range.
The researchers used a number of techniques to look at the variety of bacteria, how common these bacteria were in each sample, how many different types of bacteria were present in each stool sample, and what proportion they were in to each other.
The researchers used several statistical models to assess the relationship between stool sample results and questionnaire results. They looked at three main aspects of temperament.
The first, called negative affectivity, measures traits including fear, fidgeting, discomfort, shyness, sensitivity to surroundings and how easily the child can be soothed.
The second, called surgency, measures impulsive behaviour, how active a child is, how much pleasure they get from exciting situations, how sociable they are and how excited they get when anticipating pleasure.
The third, called effortful control, looks at a child's ability to stop doing something when told to, transfer their attention from one activity to another, take pleasure in normal activities and focus on a task.
Girls and boys tend to differ in their results on this questionnaire, with boys showing more surgency and girls more effortful control. Because of this, the researchers analysed the results for boys and girls separately.What were the basic results?
As expected, there were differences between boys and girls in the questionnaire scores for temperament. However, there was not much overall difference between boys and girls in the population of bacteria in their guts.
The researchers found both boys and girls who had greater diversity of bacteria in their gut were likely to have higher scores for "surgency". This link was stronger for boys, especially when the researchers looked at the individual scores for sociability and pleasure from exciting situations. Among girls only, they found lower levels of bacterial diversity were linked to higher scores for effortful control.
Having more of particular types of bacteria seemed to link to traits including sociability, pleasure from exciting situations and activity, but for boys and not girls. Girls who had more of one particular type of bacteria were likely to have higher scores for fear.
The researchers looked at whether the diet the children ate or how long they'd been breastfed could explain the links between gut microbiota and temperament. Although they found some links with how much vegetables or meat children ate, they say this did not explain away the links found between bacteria and temperament.How did the researchers interpret the results?
The researchers said they were "unable to determine" from the study whether the links they found were down to the effect of temperament on the gut bacteria, the effect of the gut bacteria on temperament, or a combination of the two.
But they went on to say that, if later studies show that gut bacteria does influence behaviour, this might give doctors the chance to treat children early to prevent later health problems, including mental health.Conclusion
This study found an intriguing link between the bacteria that live inside children's guts, and their personalities and behaviour. It's important to remember we don't know why this relationship exists, or whether it is the result of one factor directly causing the other.
For example, toddlers who are more active could have an increased exposure to bacteria, rather than bacteria leading to increased activity.
The researchers suggest there could be various explanations. For example, stress hormones can change the acidity of the gut, which could affect the bacteria that grow there. Bacteria in the gut can affect us through physical illness and may also affect how we feel or behave.
The study was small, and it only sampled bacteria living in the gut that get passed out of the body in stools. There are many other bacteria that live in the wall of the gut, which might also be important. However, it is difficult and painful to take samples of these bacteria.
The study also relied on the mother's assessment of the child's temperament. While that is important, having an assessment from fathers and impartial observers might help make the results more representative of the child's temperament as a whole, as children often behave differently in different situations.
While the researchers did try to take into account some factors that might influence both behaviour and gut bacteria (such as some aspects of diet), it is possible that these or other factors are in fact behind the association seen.
The relationship between the gut and the brain is an area of research that is attracting a lot of attention. That said, the idea that gut bacteria could impact our behaviour or mental health is not one that has gained widespread acceptance, and a lot more research is needed before it would be.
Links To The Headlines
Terrible twos? Why the bacteria in your child's gut may be to blame for their bad behaviour. Mail Online, May 27 2015
Links To Science
Christian LM, Galley JD, Hade EM, et al. Gut microbiome composition is associated with temperament during early childhood. Brain, Behavior and Immunity. Published online November 10 2014
"Certain breast cancers spread to the bones using an enzyme that drills 'seed holes' for planting new tumours, research has shown," The Guardian reports. The hope is drugs currently available – or possibly modified versions of them – could block the effects of this enzyme.
This largely animal and lab-based study has identified how a protein called lysyl oxidase (LOX), which some breast cancer tumours secrete, helps cancer spread to bones.
Analysis of data collected on human tumours found that in breast cancers not responsive to oestrogen, high levels of LOX production was associated with an increased risk of spread to the bones. This suggests the findings may apply to some human breast cancers as well.
Blocking the LOX protein in mice reduced the spread of cancer to the bones. Reducing the ability of the protein to create "holes" in the bone using a drug called a bisphosphonate also stopped cancer cells forming metastases in the bone.
Bisphosphonates are already used to treat osteoporosis (weakened bones) and reduce the risk of fracture in people with cancers that affect their bones. Researchers hope these drugs could also be used in people with breast cancer to reduce spread to the bone.
This will need to be tested before we can be certain that it works, but the fact these drugs are already used in humans should speed up the start of this testing process.Where did the story come from?
The study was carried out by researchers from the University of Copenhagen and other research centres in Denmark and the UK, including the University of Sheffield.
It was funded by Cancer Research UK, the Biotech Research and Innovation Centre, the University of Sheffield, the National Institute for Health Research Sheffield Clinical Research Facility, Breast Cancer Campaign, the Danish Cancer Society, The Lundbeck Foundation, the Velux Foundation, and the Novo Nordisk Foundation.
The UK media covered this story reasonably, although their headlines don't make it clear that such a drug would specifically be expected to stop spread to the bone and not necessarily other areas of the body.
The drug would also not be expected to have any effect on the breast tumour itself, so it would need to be combined with other treatments.What kind of research was this?
This was mainly a laboratory and animal study looking at how breast cancer affects the bones. Breast cancer can spread to the bone and cause the surrounding bone to be destroyed (lesions). This can cause serious complications, and the spread also makes the cancer harder to treat successfully.
The researchers wanted to investigate exactly how the breast cancer cells spread to bone and what happens within the bone when they do. They hope that by understanding this process better they may be able to find ways to stop it. This type of research is an appropriate way to study this type of question.What did the research involve?
Previous research suggests lower levels of oxygen within breast cancer tumours are associated with poorer outcomes for the patient. The researchers carried out a wide range of experiments to look at why this might be the case and unravel the biology behind this.
The researchers first looked at data on 344 women with information on the pattern of gene activity in their breast tumours, and also information on whether their tumours had later spread to the bone or elsewhere in the body.
They looked at whether a particular gene activity pattern that indicated low oxygen levels in the tumour was associated with tumour spread. An additional set of data from another 295 women was used to confirm the initial findings.
The researchers then looked at which proteins were secreted by breast cancer cells when they were exposed to low oxygen conditions in the lab. These proteins may play a role in helping the cancer spread by "preparing" other tissues for the cancer.
They then went on to study this protein in various experiments in mice. The mice were injected with mouse breast (mammary gland) cancer cells, which spread to the bones and other tissues.
The researchers looked at what effect increasing the levels of this protein had and what effect blocking it had on spread to the bone.
Bone is constantly being broken down and reformed by cells within it, so the researchers looked at what effect the protein had on the balance of these actions within the bone.
They also looked at the effect of a bisphosphonate drug on the formation of lesions. Bisphosphonates are drugs used to treat osteoporosis (thinning of the bones). They do this by reducing the number of bone-digesting cells, allowing the bone-building cells to take over the balance.What were the basic results?
The researchers found low oxygen conditions within the breast tumour were associated with cancer spread (metastases) in women with one form of breast cancer (oestrogen receptor-negative breast cancer).
It was most strongly associated with spread to the bone. This relationship was not seen in those with oestrogen receptor-positive breast cancer.
They then looked at breast cancer cells from oestrogen receptor-negative tumours in the laboratory, including cells that had spread to bone. They found a protein called lysyl oxidase (LOX) was released in high levels in low oxygen conditions, particularly in the cells that spread to the bone.
When looking back at the data they had on breast cancer tumour gene activity and outcome, higher activity of the gene encoding LOX was found to be associated with bone metastasis in oestrogen receptor-negative breast cancer.
In mice, the researchers found cancer cells were more likely to spread to the bone and form lesions when high levels of LOX were present. Injecting the mice with cancer cells producing lower amounts of LOX, or blocking the activity of LOX with antibodies, reduced the ability of the cancer cells to form lesions in the bone.
The researchers found high levels of LOX upsets the normal balance of bone formation and "digestion". It encourages more bone-digesting cells to form, overwhelming the action of the bone-forming cells and causing small lesions of destroyed bone to start to form. These lesions are then colonised by circulating tumour cells, allowing the formation of bone metastases.
The researchers found giving the mice with tumours a bisphosphonate stopped bone lesions forming, but did not affect the growth of the original tumour. Bisphosphonates also reduced the ability of injected cancer cells to settle in the bone and develop bone metastases if they were given to mice at the time of injection.How did the researchers interpret the results?
The researchers concluded they have discovered new information about the way bone metastases form from breast tumours. They say this opens up the possibility of developing new treatments for breast cancer.
They suggest that: "Bisphosphonate treatment of patients with high-LOX-expressing tumours after surgery could prevent the establishment and growth of circulating tumour cells within the bone."Conclusion
This research has identified how breast tumours create conditions that allow them to spread into the bone. Most of this research was in mice, but initial experiments suggest these findings may apply in humans as well. Researchers are likely to carry out further study to confirm this.
As part of their research, researchers found a bisphosphonate – a drug that can reduce bone breakdown – was able to reduce bone metastases in mice.
These drugs are already used to treat osteoporosis and people who have advanced malignancies affecting their bone. This means that getting approval for human studies testing the effect of these drugs on the spread of breast cancer to the bone should easier than if a completely new drug was being tested.
However, we will not know for certain whether it is effective in humans until these trials are carried out. If it does work, there will still be a lot to investigate – for example, the best dose or length of treatment to use, or when best to give it.
Researchers may also try to develop alternative ways to disrupt this pathway and stop or reduce tumour spread to the bones. New treatments would require a longer time to develop and reach the human testing stage.
Such treatments would be aimed at reducing spread to the bone, but would not be expected to have any effect on the main breast tumour itself or on spread to other parts of the body, such as the brain or lungs. This means it would need to be combined with other treatments, such as chemotherapy and surgery.
This study adds another piece of knowledge to the overall picture we have of breast cancer biology, and opens up another avenue for investigation in the search for new approaches to treatment.
Links To The Headlines
Breast cancer could be 'stopped in its tracks' by new technique, say scientists. The Guardian, May 28 2015
Breast cancer 'alters bone to help it spread'. BBC News, May 28 2015
Scientists discover mechanism that could stop breast cancer spreading to bones. The Independent, May 27 2015
Breast cancer could be 'stopped in tracks' by cheap drugs. The Daily Telegraph, May 27 2015
Links To Science
Cox TR, Rumney RMH, Schoof EM, et al. The hypoxic cancer secretome induces pre-metastatic bone lesions through lysyl oxidase. Nature. Published online May 27 2105