NHS Choices

Can you really 'catch' obesity?

NHS Choices - Behind the Headlines - Thu, 05/05/2016 - 13:00

"Obesity could be contagious like superbug C diff, suggest scientists," The Daily Telegraph reports. This rather alarming headline follows a study that explored characteristics of bacteria living in the human gut.

The study did not, however, look at any link to obesity. There's no reason to think that you can "catch" obesity from spending time with people who are overweight.

The colony of bacteria in the human gut (known as the microbiome) affects how we digest food, our immune system, how our body temperature remains stable, and other bodily functions. Little is known about the hundreds of species of bacteria living in our guts, because they were thought to be difficult to culture in the laboratory.

In this study researchers showed that about 40% of the gut bacteria known to scientists could be cultured. Further investigation found some can live and be transferred outside the body by producing spores, which are germinated by gut acids when they reach a new host – in this case another human. The superbug Clostridium difficile (C diff), which causes diarrhoea, is known to spread from person to person in this way.

Researchers did not find (or look for) any bacteria that might be linked with obesity. But in their press release, they speculated that bowel conditions such as inflammatory bowel disease, or obesity, could be caused by an imbalance of gut bacteria.

Where did the story come from?

The study was carried out by researchers from the Wellcome Trust Sanger Institute in the UK, Hudson Institute of Medical Research and Monash University in Australia. It was funded by the Wellcome Trust, the UK Medical Research Council, the Australian National Health and Medical Research Council, and the Victorian Government.

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

The Telegraph and Daily Mail both jump on the suggestion that obesity could be caused by gut bacteria and could be spread like an infection from person to person, even though the study does not look at obesity. We don't know the effects of the bacteria identified and cultured in the study.

It would be sad if this study led to obese people being labelled as "contagious", as the headlines might suggest.

The Wellcome Trust Sanger Institute's press release says: "Imbalances in our gut microbiome can contribute to complex conditions and diseases such as obesity, Inflammatory Bowel Disease, Irritable Bowel Syndrome and allergies." However, it does not suggest these imbalances are contagious.

What kind of research was this?

This was a laboratory-based study using samples of faeces from six healthy people. Researchers used genetic profiling techniques and worked with cultures on agar plates to investigate the types of bacteria found in the samples.

What did the research involve?

Researchers took stool samples from six healthy people and used gene sequencing combined with bacterial culturing to grow cultures of bacteria and identify the species found. They treated samples with ethanol, to separate out those bacteria (like C diff) which were resistant to ethanol because they formed spores.

They then looked to see how long the bacteria lived outside the human body. Most gut bacteria live in conditions with no oxygen, so they don't live long when exposed to oxygen. The researchers exposed the bacteria to acids produced in the body's bile duct, to see whether this induced the spores to "germinate", in the way that temperature and moisture induces germination in the seeds of plants.

Finally, the researchers used metagenomic sequencing (the study of genetic material) to work out what proportion of bacterial colonies in the gut are likely to be spore-forming.

What were the basic results?

The researchers said they had been able to culture 39% of bacteria identified in a database of known gut bacteria, and 73.5% of the bacteria identified in the samples in this study. They also identified new species.

They found about one third of the bacteria from their samples formed spores, and that these spores could last at least 21 days (the length of the study) of exposure to oxygen, while most non-spore forming bacteria lived for only two to six days.

When researchers exposed the bacteria to bile acids (which form part of our digestive system), the spore-forming bacteria germinated, enabling the bacteria to be cultured, while the non-spore forming bacteria were not affected.

How did the researchers interpret the results?

The researchers said they had shown that spore-formation among gut bacteria was "widespread" and that these bacteria shared characteristics with C diff, which could make them "highly transmissible for long periods" outside the body, and "have the potential to spread rapidly over long distances".

They say their research "unlocks the human intestinal microbiota" for further investigation. In their press release, they suggest they could develop treatments for conditions such as C diff infection, by creating pills with mixtures of desirable gut bacteria to compete with the bacteria causing problems.


The human microbiome is a fascinating field of research, and we are just beginning to learn how this colony of bacteria in our guts affects our health. This research widens our knowledge of these bacteria, and suggests ways they may survive and spread from person to person.

It also shows that many bacterial spores are resistant to ethanol, the main ingredient of hygienic hand gels. This reinforces the importance of using soap to wash your hands and not to rely on hand gels, especially in hospitals.

Because of the headlines in some newspapers, it's important to be clear about what the research hasn't found. It hasn't found bacteria in the gut that are responsible for causing obesity, or a link between obesity and C diff. It also hasn't found evidence that obesity spreads from person to person by bacterial transfer.

The study has simply found that about 30% of bacteria in our guts are likely to be capable of spreading from person to person. We don't know what effect that has, because we don't yet understand what role these bacteria play in the gut.

If you are worried about your weight, take a look at our weight loss guide; you can find out what weight is healthy for your height, and get advice on how to lose weight sensibly if you need to. 

Links To The Headlines

Obesity could be contagious like superbug C. diff, suggest scientists. Daily Telegraph, May 5 2016.

Is obesity CONTAGIOUS? Spores of bacteria from guts of fat people 'could spread to healthy individuals'. Mail Online, May 5 2016.

Links To Science

Browne HP, Forster SC, Blessing O, et al. Culturing of 'unculturable' human microbiota reveals novel taxa and extensive sporulation. Nature. Published online May 4 2016


Categories: NHS Choices

Diluted apple juice 'as good as' rehydration drinks for children

NHS Choices - Behind the Headlines - Wed, 04/05/2016 - 13:00

"Scientists have revealed which fruit can stop toddlers crying due to stomach pains," says the Daily Mirror, missing the point of the study it reports on.

The study looked at the use of diluted apple juice to prevent dehydration in children with upset stomachs.

When children get diarrhoea or vomiting, the main danger is that they will lose too much fluid (become dehydrated). Severe dehydration can be life-threatening and can happen quickly in young children.

To prevent this, doctors often recommend giving them specially made rehydration drinks, with a mixture of salts and sugars designed to keep fluid levels stable. However, the drinks are expensive and some children don't like the taste.

The researchers wanted to see if rehydration drinks were actually better, or if drinking diluted apple juice followed by children's usual preferred drinks would work just as well for children aged over six months.

The study found that children given apple juice were less likely to need additional treatments – possibly because they were happier with the taste and more willing to drink the juice.

However, this may not work for all children, as the study didn't include any babies under six months, children with more serious stomach upsets or other conditions, and those who were already severely dehydrated.

The advice from the National Institute for Health and Care Excellence (NICE) is still to give your child rehydration solution if you're worried they may become dehydrated and to seek medical advice if they don't get better. Fruit juice could make their diarrhoea worse and the current advice is that it should be avoided.

Where did the story come from?

The study was carried out by researchers from the University of Calgary, the University of Toronto and the Hospital for Sick Children and Child Health Evaluative Services in Toronto, all in Canada. It was funded by the Physician Services Incorporated Foundation.

No apple juice producers were involved in the funding of this study and the authors reported no conflict of interests.

The study was published in the peer-reviewed Journal of the American Medical Association (JAMA), on an open-access basis, meaning it is free to read online.

The study seems to have confused the UK media. The Daily Express says "an apple a day" might cure children's tummy aches, the Daily Mirror says apples "could stop toddlers crying", while the Daily Mail says apples "could keep tummy bugs at bay".

All the headlines miss the point that the apple juice was tested as a treatment to prevent dehydration when a child has a bug, not to prevent stomach aches or infections. There's no evidence in the study to back up these headline claims.

What kind of research was this?

Researchers carried out a single-blind randomised controlled trial (RCT), to see whether diluted apple juice followed by the child's normal preferred drinks (such as milk, water or juice) worked as well to prevent dehydration as rehydration solutions.

RCTs are a good way to see which of two treatments works best. But in this case, the study was designed to see whether apple juice worked as well as rehydration solutions, not to say for certain which works best.

What did the research involve?

Researchers from a specialist children's hospital recruited 647 children aged from six months to five years who'd been brought into the emergency department with an upset stomach. Children were randomly divided into two groups and assigned to the different treatments.

The children were given their allocated fluids, designed to look the same, as soon as they'd been seen by the nurse. Their parents were told to start giving them sips of the fluid straight away. They were then seen by a doctor, who could change the treatment if necessary.

When they went home, parents were told to either keep on using the rehydration salts to replace fluid lost by diarrhoea or vomiting, or to use the diluted apple juice followed by the child's normal preferred drink. A research nurse phoned daily to check how they got on.

At the end of the study, researchers compared how many children had either needed additional treatment (such as fluids given through an IV drip) or to switch to the other treatment, or had long-lasting illness, dehydration or weight loss, or needed to go back to hospital or see the doctor with the same episode of upset tummy, within seven days.

A combination of any of these factors was called a "treatment failure".

They analysed the results to see if apple juice worked as well as rehydration salts, and to look for patterns that might explain it, such as the child's age.

What were the basic results?

Children who had apple juice followed by their preferred drinks did at least as well as those who had rehydration drinks:

  • 16.7% of children who'd had apple juice had treatment failure, and 2.5% needed fluids given through a drip
  • 25% of children who'd had rehydration drinks had treatment failure, and 9% needed fluids given through a drip

There were no significant differences between the two treatments in terms of frequency of diarrhoea and vomiting, weight loss and admission to hospital.

How did the researchers interpret the results?

The researchers say that diluted apple juice "may be an appropriate alternative" to rehydration drinks for children with mild tummy upsets in high income countries such as Canada, where few children get serious infections and there's easy access to healthcare.

They warn the results may not be relevant to low and middle income countries where children are more likely to get serious infections and to become dangerously dehydrated.

They point out that parents have been discouraged from giving children with stomach upsets sugary drinks like fruit juice, because it could make diarrhoea worse. However, they say their results provide evidence that "in children with minimal dehydration, promoting fluid consumption is more important" than how much sugar is in the fluid.

They say that children over two years of age seemed to get most benefit from apple juice, perhaps because they were more used to drinking sweetened drinks and were fussier about taste.


This study shows that diluted apple juice may work as well as rehydration salts for children with mild stomach upsets in preventing dehydration. But it might not work for all children, especially those with more serious stomach upsets, babies under six months, or children who are already more severely dehydrated.

It's important to remember that the children in this study were seen by a doctor before being allowed to continue with the diluted apple juice. They were all over six months old, didn't have other conditions that might have made the stomach upset more serious (such as diabetes) and had been checked for dehydration or other signs of serious illness.

There is also some missing information from the study that could have affected the results. We don't know whether parents continued to use apple juice or rehydration drinks as directed when they got home, or whether the child was receiving any treatment other than the hydration or anti-sickness tablets.

Most of the study results came from databases recording treatments given and visits to doctors or hospitals, or from phone calls by research nurses to the families after they'd left hospital. Not many parents returned the diary they'd been given to record their child's symptoms and whether the parents were happy with the treatment, so we don't know for sure if the parents were happy with the advice and their child's recovery.

If other studies also show that diluted apple juice works well for children with mild stomach upsets, doctors might decide to start recommending it instead of rehydration drinks.

For now, NICE advice is to encourage your child to drink fluids when they have a tummy bug, but to avoid giving your child fruit juice. See a doctor if you're worried your child is losing too much fluid.

Links To The Headlines

An apple a day could keep tummy bugs at bay: Toddlers given watered down juice recover from illness quicker. Mail Online, May 3 2016.

Scientists have revealed which fruit can stop toddlers crying due to stomach pains. Daily Mirror, May 3 2016.

Diluted apple juice 'ideal for treating tummy bug in children'. Daily Express, May 3 2016.

Links To Science

Freedman SB, Willan AR, Boutis K, et al. Effect of Dilute Apple Juice and Preferred Fluids vs Electrolyte Maintenance Solution on Treatment Failure Among Children With Mild Gastroenteritis: A Randomized Clinical Trial. JAMA. Published online April 30 2016.

Categories: NHS Choices

Gene breakthrough promises 'bespoke' breast cancer treatment

NHS Choices - Behind the Headlines - Tue, 03/05/2016 - 14:30

"Breast cancer treatment breakthrough after 'milestone' genetic discovery," says The Independent, about widely reported research investigating genetic mutations in people with breast cancer.

The researchers took samples of cancer cells from 560 people with breast cancer (556 women and four men). They compared the DNA from the cancerous cells with DNA from normal cells.

They found 93 genes that had mutated in the cancer cells and concluded that they could have caused normal tissue to become cancerous. They also found 12 genetic patterns linked with breast cancer.

These findings have been called "groundbreaking" in the media. While they are certainly interesting, it's important to remember that, even if the gene is present, it doesn't mean the person will get cancer, just that their risk is increased.

It's hoped that the study will lead to more personalised treatments for breast cancer, similar to drugs used for other DNA mutations that are already known.

If there is a history of breast cancer in your family, you may be worried about your own risk. It's best to visit your GP, who can assess you and refer you to a genetic clinic if necessary.

The study was carried out by researchers from a number of institutions, including the Wellcome Trust Sanger Institute, East Anglian Medical Genetics Service, and the Cambridge University Hospitals NHS Foundation Trust.

Funding for the study was provided by multiple organisations, including the European Community's Seventh Framework Programme, the Wellcome Trust and the Institut National du Cancer (INCa) in France. The ICGC Asian Breast Cancer Project was funded through a grant from the Korean Health Technology R&D Project, Ministry of Health and Welfare, Republic of Korea.

The study was published in the peer-reviewed scientific journal Nature.

These findings have been reported accurately in the media. It's good to see explanations stating that, while this may be an important discovery, it may still be decades before targeted treatments become available. One of the researchers told the media: "Overall, I'm optimistic, but it's a tempered optimism".

Links To The Headlines

Breast cancer treatment breakthrough after 'milestone' gene discovery. Independent, May 3 2016

Breast cancer breakthrough: Hope for new treatments after scientists uncover detailed picture of genetic events that cause it. Daily Mail, May 3 2016

Breast cancer: Scientists hail 'milestone' genetic find. BBC News, May 3 2016

Study points towards personalised treatment for breast cancer. The Guardian, May 3 2016

Links To Science

Nik-Zainal S, Davies H, Staaf J, et al. Landscape of somatic mutations in 560 breast cancer whole-genome sequences. Nature. Published online May 2 2016

Categories: NHS Choices

Does 'ginger gene' offer key to younger looking skin?

NHS Choices - Behind the Headlines - Fri, 29/04/2016 - 14:30

"'Secret' of youthful looks in ginger gene," BBC News reports. Dutch researchers have found evidence that a gene associated with red hair – the MC1R gene – may also have an impact on how young or old a person looks for their age.

This study examined the facial appearance and genetics of thousands of Dutch elderly adults. The researchers found four DNA sequence variants in the MC1R gene were linked to perceived facial age. These variants were already known to be associated with red hair, pale skin and sun spots.

People who carried two copies of these variants looked almost two years older than people who didn't carry any. Those who carried a single copy looked about one year older.

The researchers hope their findings may spark new leads into understanding the biological basis of youthful looks, and maybe even lead to new anti-ageing treatments.

However, this is some way off. There are likely to be various other genetic factors associated with ageing.

Of course, our genetics don't provide the whole answer to youth and vitality. Our lifestyle and environment – such as whether we drink or smoke and how much UV exposure we get – have a massive influence.

All of these factors can cause premature ageing of the skin. Conversely, a good diet and regular exercise can help boost the appearance of your skin.

We can't change our genetics, but we can change our lifestyle to give us the best chance of a healthy and happy life.

Read more about how to look after your skin

Where did the story come from?

The study was carried out by researchers from the Beijing Institute of Genomics in China, Erasmus MC University Medical Center and Leiden University Medical Center in the Netherlands, and the University of Leeds.

Funding was provided by the Erasmus University Medical Center Rotterdam, Unilever, and the Netherlands Genomics Initiative and the Netherlands Organization of Scientific Research.

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

Three of the authors work for Unilever. The study says: "Although no products were tested, this work could potentially promote the use of anti-ageing products and lead to financial gain for Unilever."

Some sections of the media got themselves into a right muddle regarding the implications of the research, as several headlines imply that redheads look two years younger. This isn't the finding of this research.

The study examined four variants in the MC1R gene that are known to be associated with red hair, pale skin and sun spots.

It found people who carried two copies of any of these four variants looked two years older. So, if anything, this seems to imply that the "ginger" variants were associated with looking older, not younger.

But it's not as simple as this. The variants were lumped together, so you can't assess the effect of any particular variant combination, therefore muddying any specific links.

The researchers also don't make any explicit links with hair colour or skin colour – and argue age perception was independent of these variables.  

Why the MC1R gene can have an influence on skin appearance therefore remains a mystery.

What kind of research was this?

This genome-wide association study involved a large cohort of Dutch people of European descent. It aimed to identify genes linked to perceptions of facial ageing and wrinkles.

As the researchers say, the desire to look young for your age is a long-standing one, which is likely to be due to its associations with health and fertility.

However, the biological basis of why people look older or younger for their age isn't understood. Understanding this could potentially be a step towards the development of new anti-ageing therapies.

What did the research involve?

The first part of the study involved participants of the Rotterdam study – an ongoing follow-up cohort set up in 1990 that has included 2,693 elderly Dutch Europeans.

Researchers of all ages, mainly British, looked at front and side photos of their faces and guessed their age to fit within five-year age bands.

Facial features such as wrinkles and pigment marks were measured objectively using image analysis software.

The researchers then analysed participants' entire DNA, looking at more than 8 million single letter variants – single nucleotide polymorphisms, or SNPs – in the DNA sequence to identify those that had the strongest link with perceived facial age. 

The researchers then verified their findings in two other cohorts: the Leiden Longevity Study, including 599 Dutch Europeans, and the TwinsUK Study, including 1,173 female Europeans.

What were the basic results?

In the Rotterdam cohort, the researchers identified several DNA variants on the MC1R gene that were significantly associated with perceived age, after adjustment for age, sex and wrinkles.

Four of these MC1R DNA variants were highlighted as markers for further study, given that they have been previously associated with red hair, pale skin and age spots.

Compared with people who did not carry any of these four variants, people who carried a single copy of one of them looked about one year older, while people who carried two copies of any of the ageing variants looked about two years older. The effect of these variants seemed to be greater in men than women.

In the Leiden and Twin studies, they confirmed the association with these four MC1R DNA variants.

The link seemed to be consistent regardless of sun exposure and skin colour, but was weaker for darker skin tones.   

How did the researchers interpret the results?

The researchers concluded that, "A role for MC1R in youthful looks independent of its known melanin [pigment] synthesis function is suggested.

"Our study uncovers the first genetic evidence explaining why some people look older for their age and provides new leads for further investigating the biological basis of how old or young people look."


As the researchers rightly say, the quest for prolonged youth and vitality is a longstanding one. This study uncovers another possible genetic reason why some people of the same age may look slightly older or younger than each other. 

The researchers hope their findings may spark new leads into understanding the biological basis of youthful looks, and maybe even one day lead to new anti-ageing treatments.

The findings will undoubtedly provide a valuable contribution to the science of ageing, but we shouldn't assume that DNA sequence variants in the MC1R gene give the whole answer.

There are likely to be many other unexplored genetic variants that have a link with ageing, maybe with greater or less of an effect than the variants studied here.

Of course, our genetics don't give the whole answer to youth and vitality. Our lifestyle and environment – such as our diet, the amount of exercise we take, whether we drink or smoke, and how much UV exposure we give our skin – have a massive influence.

Another factor to consider is that this study was only looking at perceived ageing on account of how the person's face looked. Looking more youthful may not necessarily correlate with good physical health and fertility.

If new anti-ageing treatments are developed, they will be some way down the line, and one thing we can't change is our genetics.

What we can change, though, is our lifestyle to give us the best chance of a healthy and happy life.

Find out how becoming more active can boost both your mental and physical wellbeing – so even if you don't look younger, you could end up feeling younger.   

Links To The Headlines

'Secret' of youthful looks in ginger gene. BBC News, April 29 2016

Gene linked to youthful looks has been discovered, scientists claim. The Guardian, April 28 2016

Ginger gene helps you to look two years younger. The Daily Telegraph, April 29 2016

Secret to 'eternal youth' found in GINGER gene that makes you look two years younger. Daily Mirror, April 28 2016

Secret of looking younger revealed: Half of us have an 'ageing gene' (and it helps redheads look TWO years younger). Mail Online, April 29 2016

Links To Science

Liu Fm Hamer MA, Deelen, J, et al. The MC1R Gene and Youthful Looks. Current Biology. Published online April 28 2016

Categories: NHS Choices