“Anti-baldness drug can cause men to lose interest in alcohol,” reports the Mail Online.

This report is based on a small survey of young men who had been taking the drug, finasteride, for hair loss. Impotence and decreased libido are recognised side effects of this anti-male-hormone drug, and all 83 men in this study had experienced sexual side effects that lasted at least three months after they stopped taking it.

The survey found that the men reported drinking less at the time of the survey than before they started taking the drug. However, this was on average five years earlier, so it is not clear how well these men could remember what they drank so far in the past.

Also, as the study had no control group who didn’t take the drug, it’s not possible to say that these changes wouldn’t have happened naturally over time as the men aged. The results may also not be representative of what might be seen in older men, men taking the drug for its other use (enlarged prostate), or men who do not experience the sexual side effects of the drug.

Overall, these findings are inconclusive. Larger studies, ideally with a control group, are needed to assess the effects of the drug on alcohol consumption.

Where did the story come from?

The study was carried out by a single researcher from The George Washington University in the US. No sources of funding were reported. It was published in the peer-reviewed journal Alcoholism: Clinical and Experimental Research.

The Mail Online reports the results of the study, but not any of its fairly extensive limitations.

What kind of research was this?

This was a cross-sectional study reporting on the alcohol consumption among men taking the drug finasteride. This anti-male-hormone drug is licensed to treat benign (non-cancerous) enlargement of the prostate and male pattern hair loss.

The recognised side effects of the drug include sexual problems such as decreased libido, impotence and erectile dysfunction. It may also have effects on the nervous system. The researchers reported that finasteride has been shown to reduce alcohol intake in male mice, but no studies have assessed this in humans.

This study relied on men reporting their own alcohol consumption before and after taking the drug in a single survey. This is likely to be less reliable as men may not accurately remember their consumption in the past. Asking the men to keep an alcohol diary before and after they started taking the drug would be a more reliable approach.

The study also didn’t include a comparison group not taking the drug. Therefore, the result cannot conclusively show that the drug itself is definitely causing a change in alcohol consumption.

What did the research involve?

The researchers surveyed the alcohol consumption habits in 83 men aged under 40, who had been taking finasteride to treat or prevent male pattern hair loss. These men had experienced persistent sexual side effects but were otherwise healthy.

The men were reported to be recruited from the author’s previous studies on persistent sexual side-effects of finasteride. These men had side-effects for at least three months despite stopping finasteride. Men who had sexual dysfunction before taking finasteride, had chronic medical conditions, current or past psychiatric conditions, or had taken psychiatric medication were excluded.

The survey asked about their average weekly alcohol consumption before they started taking finasteride, and at the time of the interview. A glass of wine, can of beer, or shot of hard liquor was considered a standard drink.

What were the basic results?

Sixty-three of the men reported drinking at least one alcoholic drink per week before starting finasteride. Among these men, at the time of the survey:

• 65% reported reduced alcohol consumption 
• 32% reported no change in their alcohol consumption
• 3% reported an increase in their alcohol consumption

On average, of the men who reported drinking alcohol, the average number of drinks per week reduced significantly – from 5.2 before finasteride to 2.0 after finasteride. As the men had stopped taking finasteride, they were not taking the drug at the time of assessment.

The authors reported that although they were not asked about this specifically, some men volunteered the information that they could not tolerate alcohol as well after starting to take finasteride. Eighteen men reported giving up alcohol entirely.

How did the researchers interpret the results?

The researchers concluded that among men who developed persistent sexual side effects from finasteride and stopped taking the drug, almost two-thirds reported reduced alcohol consumption.

Conclusion

This relatively small study in a very select group of men provides only limited evidence of the effects of finasteride on alcohol consumption in men. Its limitations include:

• The study didn’t include a comparison group not taking the drug. Therefore, the result cannot conclusively show that the drug itself is definitely causing a change in alcohol consumption, rather than the men just having changing alcohol tolerance as they got older.
• The study asked men to remember what their alcohol consumption was before taking the drug – on average about five years previously. This is likely to be less reliable as men may not accurately remember their consumption in the past. Asking the men to keep an alcohol diary before and after they started taking the drug would be a more reliable approach.
• The study only used a crude assessment of the number of drinks consumed, the size and alcohol content of these drinks may vary and this could affect comparison of before and after findings.
• The study did not say exactly how men were selected to take part, or whether they knew the purpose of the study. The men’s responses may have altered if they knew that finasteride may have an effect on alcohol consumption.
• The men all had persistent sexual dysfunction following taking finasteride for male pattern hair loss. The results may not apply to other men taking the drug, for example those without these side effects, or those taking it for an enlarged prostate.
• The author reported that many of the men in the study experienced depressive symptoms, and this may have affected their alcohol consumption.

As the author acknowledges, more research would be needed to determine the effects of finasteride on the nervous system and alcohol consumption.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Anti-baldness drug can cause men to lose interest in alcohol. Mail Online. June 17 2013

Links To Science

Irwig MS. Decreased Alcohol Consumption Among Former Male Users of Finasteride with Persistent Sexual Side Effects: A Preliminary Report. Alcoholism: Clinical and Experimental Research. Published online June 13 2013

“'Cradle snatchers' cause menopause, says biologist,” is the bizarre headline in The Guardian today.

The menopause has always been a bit of an evolutionary puzzle. Evolution is about one thing only – reproducing genes. So why would genes that cause a woman to lose fertility halfway through her life survive?

Two main theories have been previously suggested:

• one theory suggests the menopause is a trade-off in increased fertility versus prolonged survival 
• the second theory is known as the “grandmother effect”, whereby older, post-menopausal women are no longer fertile so they can instead help out with raising their grandchildren

A new study has provided a third theory. Humans started off with prolonged fertility, but if men theoretically preferred mating with younger women there would be no pressure to weed out the mutations that cause infertility in later life. According to this theory, over time mutations affecting fertility in older women accumulate – leading to most, and then all, women experiencing menopause.

Researchers used a complicated computer model to run a number of evolutionary cycles and found that the model was consistent with their theory. But it’s not possible to say conclusively that this model accurately represents what has happened in human evolution, and other factors may contribute.

The findings are interesting but they have no direct health implications. Menopause – for whatever reason it may occur – is a natural part of human female life, to which no blame should be attached.

Where did the story come from?

The study was carried out by researchers from McMaster University, Ontario, Canada, and was funded by the Origins Institute and Shared Hierarchical Academic Research Computing Network at McMaster University, and the Natural Sciences and Engineering Research Council of Canada.

The study was published in the peer-reviewed open access scientific journal PLoS Computational Biology.

The media reporting of the theory is broadly accurate but it is just that, a theory. This complex computer modelling research can only suggest certain scenarios that could potentially explain the observations seen. It is not possible to say conclusively that these models do represent what truly happened.

Headlines that suggested men are “to blame for the menopause” are a bit silly. Evolutionary forces are not something anyone has any control over. Blaming men for the menopause is like blaming someone other hereditary conditions that have evolved in humans over time, say, sickle cell anaemia.

A number of the news sources carry a quote from another expert critical of the theory. Dr Maxwell Burton-Chellew, an evolutionary biologist in the department of zoology at the University of Oxford, was quoted as saying: “This [theory] is probably the wrong way round - the human male preference for younger females is likely to be because older females are less fertile.”

What kind of research was this?

This was a computer modelling study trying to determine why women undergo menopause.

As the authors note, survival beyond the menopause is a characteristic that appears almost unique to humans with only odd exceptions (such as whales, and chimps in captivity). Evolutionary theories suggest that natural selection should operate against living beyond reproductive age and it is not clear (theoretically) why women live beyond the menopause.

At least two possibilities have been put forward to explain this phenomenon: a trade-off favouring longer lifespan over reproduction in women (because giving birth when older may increase mortality risk); and that menopause increases the reproductive success of the woman’s offspring (that is, the “grandmother effect” of older women being able to assist their children in rearing their own children).

Other researchers have suggested that living beyond menopause could be down to an influence from males. They suggest that the fact that men remain fertile throughout their lifespan would prevent accumulation of lifespan-shortening mutations, allowing men and women to live longer. However, this does not explain why women undergo menopause.

The current research aimed to test the effect of male mating preference on the evolution of the menopause. In particular, they were interested in the effect a male mating preference for younger females would have.

What did the research involve?

The research involved a complex computer model that looked at the effect on a population of male lifelong fertility and of male mating preference on female fertility.

The researchers modelled a population of a fixed size, which initially had pre-set fertility and survival probabilities. Each individual started the model in one of 18 increasing age classes. Survival probability for each age group (determined by the number and type of mortality-causing mutations introduced) was assessed at five-year intervals.

The different computer models then introduced mutations into the population that separately affected mortality and fertility – mutations that affected fertility did not affect survival, and mutations that affected survival did not affect fertility.

This determined whether any individual in each age group died or went into the next age bracket. All individuals that reached the oldest age class (class 18) died in the model.

Deaths in the model were replaced by new births assigned to the first age category. The births were simulated by randomly selecting a male from the surviving male population, and a female from the surviving female population. Male and female fertility probabilities in the model were influenced by the number and type of fertility-affecting mutations that had been introduced into the population.

The researchers used their model to look at two scenarios.

First scenario

In their first scenario, men retained lifelong fertility, while women underwent menopause. In this scenario men did not have an age-specific mating preference. The researchers looked at the effect of introducing into the population theoretical genetic mutations that reduced lifespan but did not affect fertility.

Second scenario

In their second scenario, the researchers started out with men and women being fertile all their lives. They then introduced mutations that caused reducing fertility, and mutations that affected survival. They looked at the impact on this scenario of men having a preference for mating with younger females.

What were the basic results?

In their first scenario – where men did not have an age-specific mating preference and women underwent menopause – the researchers found that if men retained lifelong fertility this did prevent
mortality-causing mutations from accumulating in females. However, this does not explain why menopause came about.

In their second scenario - where both sexes started with lifelong fertility and men preferred to mate with younger females – over time the mutations reducing female fertility with age accumulated in the population, causing a decline in female fertility with age; effectively the menopause. 

However, a similar effect was not seen if male mating preference was not influenced by women’s age.

How did the researchers interpret the results?

The researchers say that their model suggests that male mating preference for younger females could have driven the evolution of menopause. Their model did not need the presence of the other suggested explanations for the menopause to be present in order to work (the trade-off between fertility and lifespan and the “grandmother effect”). Instead they say that these explanations “may be insufficient factors in elucidating the origin of menopause”.

Conclusion

This computer modelling study has suggested that a male preference for mating with younger females could be the reason why menopause evolved in humans. However, whether this is truly the reason, or whether other factors some into play is not possible to say.

While this may be of interest to sociologists and others interested in the possibilities of human evolution, it has no direct health implications.

Unless someone comes up with a working time machine there is little we can do about the genetic cards that evolution has dealt us.

If you are experiencing the menopause, tempting as it may be to start blaming the men in your life, you are better off seeking support from your doctor, who may be able to offer treatment for particular symptoms of menopause.

A commonly used treatment is hormone replacement therapy (HRT), although there are also alternatives for women are not suited to HRT.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

'Cradle snatchers' cause menopause, says biologist. The Guardian, June 13 2013

Men 'to blame for the menopause'. BBC News, June 14 2013

Men may be to blame for the menopause. The Daily Telegraph, June 13 2013

Did man's yearning for young women create the menopause? Research suggests that men's wandering eyes may have caused middle-age loss of fertility in women. Mail Online, June 14 2013

Links To Science

Morton RA, Stone JR, Singh RS. Mate Choice and the Origin of Menopause. PLoS Computational Biology. Published online June 13 2013

Electronic cigarettes are to be licensed and regulated as an aid to quit smoking from 2016, it has been announced.

E-cigarettes – battery-operated devices that mimic cigarettes – are to be classed as 'medicines', which means they will face stringent checks by medicine regulator the MHRA and doctors will be able to prescribe them to smokers to help them cut down or quit.

This move has been widely welcomed by medical experts and officials, as tighter regulation will ensure the products are safe and effective.

Until this happens, e-cigarettes are only covered by general product safety legislation, meaning they can legally be promoted and sold to children, and we cannot be sure of their ingredients or how much nicotine they contain. The MHRA will not ban the products entirely during this interim period, but will encourage e-cigarette manufacturers to apply for a medicine licence.

Are e-cigarettes safe?

We don’t really know until they have been thoroughly assessed and monitored in a large population over time. However, compared with regular cigarettes, they are certainly the lesser of two evils.

First, e-cigarettes don’t contain any tobacco – only nicotine, which is highly addictive but much less dangerous. For this reason, smoking e-cigarettes (known as ‘vaping’) is generally regarded a safer alternative to smoking for those unable or unwilling to stop using nicotine.

Also, while the US Food and Drug Administration (FDA) found the liquid and vapour to contain traces of toxins (PDF, 237kb), including cancer-causing chemicals nitrosamines and formaldehyde, the level of these toxins is about one thousandth of that in cigarette smoke.

We cannot be certain that these traces of toxins are harmless, but tests on animals and a small study of 40 smokers are reassuring, providing some evidence that e-cigarettes are well tolerated and only associated with mild adverse effects (slight mouth or throat irritation, a dry cough).

Public health charity Action on Smoking and Health (ASH) is cautiously optimistic, concluding in its January 2013 briefing (PDF, 447kb) that ‘there is little evidence of harmful effects from repeated exposure to propylene glycol, the chemical in which nicotine is suspended.’

Others are more wary. Some health professionals do not recommend them because they believe the potential for harm is significant. It is worth bearing in mind that nicotine is not altogether harmless – for example, it has been linked to anxiety – and research suggests nicotine plays a direct role in the development of blood vessel disease.

E-cigarettes are banned by other countries and by some UK schools concerned about their influence on adolescents (see ‘What are the other concerns?’). 

What do e-cigarettes contain, and how do they work?

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 also 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.

Will they help me quit smoking?

We don’t yet know. The evidence so far is promising, but not strong enough to draw any firm conclusions.

A 2011 study and a 2013 survey found that e-cigarettes decreased the number of cigarettes consumed by smokers, and the survey also suggested they reduce cigarette cravings – although participants were recruited from websites of e-cigarette manufacturers, so results may not be representative.

It’s not certain whether e-cigarettes deliver as much nicotine as forms of nicotine replacement therapy such as patches, so they may not be as effective at curbing nicotine cravings.

However, they do have the advantage of looking and feeling like cigarettes: they satisfy the same hand-to-mouth action, give out a smoke-like vapour, and some even have an LED light that resembles the burning tip of a cigarette. This could be why a 2010 study found that even placebo e-cigarettes (with no nicotine) relieved the desire to smoke within the first 10 minutes of use.

If you want to try a safer alternative to cigarettes but are concerned about the uncertainties surrounding e-cigarettes, you may wish to consider a nicotine inhalator. This licensed quit smoking aid, available on the NHS, consists of just a mouthpiece and a plastic cartridge. It’s proven to be safe, but the nicotine vapour only reaches the mouth rather than the lungs, so you don’t get the quick hit of nicotine that comes with e-cigarettes (see box below, which compares e-cigarettes with inhalators).

E-cigarettes vs nicotine inhalators

Is there any risk to others from e-cigarette vapour?

It’s not clear until more studies are done (see ‘Are e-cigarettes safe?’). Research to date has not shown the vapour to be harmful – it largely consists of water.

According to ASH: “Any health risks of secondhand exposure to propylene glycol vapour are likely to be limited to irritation of the throat.” To support this, it cites a 1947 study that exposed animals to propylene glycol for 12-18 months at doses 50 to 700 times the level the animal could absorb through inhalation. Compared to animals living in a normal room atmosphere, no irritation was found, and the kidney, liver, spleen and bone marrow were all found to be normal.

What are the other concerns?

Because e-cigarettes can be smoked in public places such as bars, restaurants and public transport, some people feel they may be normalising what has come to be seen as an unacceptable activity.

Also, some argue that e-cigarettes (with their flavourings and clever marketing) are a ‘gateway to smoking’ for children and teenagers, encouraging them to smoke when they wouldn’t otherwise take up the habit.

If they're not a gateway to smoking, they are at least a gateway to nicotine addiction. Cancer Research UK asks whether smokers who may have otherwise successfully conquered their nicotine addiction may be more likely to stay on e-cigarettes (and thus be addicted to nicotine) long term, if they start using them.

However, these are just theories and questions, which need to be properly researched before we can jump to any conclusions, and their potential influence on children will hopefully not be an issue when e-cigarettes are tightly regulated as a medicine.

Where do I buy e-cigarettes, and how much do they cost?

E-cigarettes are widely available online and from newsagents, supermarkets and even some pharmacies. They are currently not available on the NHS.

A single disposable e-cigarette costs about £6. A starter kit costs anything from £17 to £90 (many retail at around £35-£45). For this, you typically get a battery, a charger and two or more replaceable cartridges containing nicotine. When the cartridges run out, a four-pack of refills will cost you £10-£17. In all, they are estimated to be 20% cheaper than cigarettes (this may be an underestimate).

How long do they last?

E-cigarette manufacturers say that a refill cartridge is equivalent to anything from seven to 25 regular cigarettes, depending on its nicotine content – but these may be overestimates, and its duration obviously depends on how heavily you use the device. The battery is said to last between two and five hours.

This page was updated on June 12 2013.

Analysis by NHS Choices. Follow Behind the Headlines on Twitter.

“If you’re worried about going grey – try to relax”, the Daily Mail advises its readers, adding, “scientists have found that too much stress really does turn our hair white”.

However, the claim is simply not true.

The research this story is based on actually involved mice and human scalp cells in a lab. It looked at a group of cells known as melanocyte stem cells (McSCs) – a type of stem cell that produces melanin, a pigment responsible for skin and hair colour.

Stem cells can develop into many different cell types in the body and play a crucial role in maintenance and repair. The researchers wanted to see how McSCs reacted to three types of intervention; injury, exposure to ultraviolet B (UVB) radiation, and stress hormones.

Using both mice and samples of human tissue, the researchers found that a combination of injuries caused some of the McSCs to ‘migrate’ out of hair follicles and into the affected area of tissue.

However, it was also found that stress hormones only increased the ‘migration’ of melanocytes in the skin when the skin was damaged – in this case by exposure to UVB.

When only the stress hormones were present, no skin melanocyte stem cells were produced.

This is an interesting study, but going grey may involve many factors – including the genes we inherit. The theory that stress is a cause has yet to be proved.

One practical application of the research is that it could lead to the development of treatments which manipulate the behaviour of McSCs, which could be used for skin pigmentation disorders such as vitiligo (pale white patches on the skin, caused by lack of melanin) and piebaldism (a condition in which white patches develop on the skin).

Where did the story come from?

The study was carried out by researchers from New York University School of Medicine and Baylor College of Medicine, US. The study had no external funding, but two of the researchers are supported by, or have grants from, a number of public institutions.

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

Not surprisingly, the study was covered widely in the press, where it was reported with a spin promising ways to avoid going grey. The press coverage focussed on the possibility (presented as fact) that stress hormones have the potential to turn hair grey. However, there is some distance between experiments on mice and human skin cultures and the development of treatments against grey hair.

What kind of research was this?

This was laboratory research using mice and mouse and human skin cultures. Its aim was to look at the behaviour of melanocyte stem cells (McSCs) and whether these can migrate from the hair follicles to the skin.

What did the research involve?

Researchers carried out several studies. These included the following:

• Experiments on mice. Mice are different from humans in that the melanocytes in the skin disappear shortly after birth but remain in the hair follicle (presumably because mice have a coat and therefore don’t need them in their skin). The researchers used genetically modified mice with markers allowing them to track the movement of certain cells. The researchers created a small 1cm² cut on the back of mice or exposed an area of skin to UVB and looked at whether melanocytes and melanocyte stem cells moved from the hair follicle to the skin, and what happens after that.
• Experiments on human scalp cultures to look at whether the same process happens in human skin. In this experiment, they removed melanocyte cells in the skin and analysed whether melanocytes in the follicles migrated to the skin.
• They looked at the role of Mc1r, a stress hormone receptor, in the migration of McSCs from hair follicles to skin – hormone receptors are proteins on the surface of cells that react to the effects of certain hormones. To do this they used genetically modified mice and cultured mouse cells.

What were the basic results?

Researchers found that in mice that had been cut or exposed to UVB, melanocyte stem cells moved from the hair follicle to the skin, where they produced melanocytes.

Normally, stem cells renew themselves as well as producing cells that go on to form new tissue. However, the researchers found that the stem cells moved without replicating, meaning that after damage there were fewer melanocyte stem cells in the hair follicles surrounding the wound.

After a cut, some hair follicles surrounding the wound had no melanocyte stem cells, causing the hairs growing out of that follicle to be white.

After UVB exposure, there were still enough stem cells for the hair to be coloured. The fact that stem cells move suggests that recovery from injury takes precedence over stem cell maintenance.

New hair follicles that developed in patches of repaired skin were coloured if they developed in areas of skin that had melanocytes. This suggests that the melanocyte stem cells that had migrated to the skin could revert back to follicular stem cells.

A similar process occurred in samples from human scalp (once skin melanocytes were removed, they could be replaced by melanocytes originating from the hair follicle).

The researchers then tried to determine how the stem cells were moving. They saw that a receptor on the surface of melanocytes (Mc1r) plays a role – this receptor responds to stress hormones. Fewer stem cells moved in mice that lacked this receptor.

The researchers then did an experiment where they cultured mouse skin in the presence of a stress hormone. The stress hormones increased the production of melanocytes in the skin but only when the skin was damaged – in this case by exposure to UVB.

When only the stress hormone was present, no skin melanocyte stem cells were produced.

How did the researchers interpret the results?

The researchers say that stem cell differentiation due to injury takes precedence over stem cell maintenance. The melanocyte stem cell mechanism could be manipulated they say, to develop therapies for skin pigmentation disorders. They speculate the mechanism could also explain why stress may cause both skin pigmentation and paradoxically, hair greying.

Conclusion

This is an interesting study and its results may eventually lead to the development of treatments for skin pigmentation disorders. Stress hormones also seem to be involved in the movement of melanocyte stem cells from hair follicles to the skin but the relationship appears complicated, involving multiple factors. Whether stress by itself causes hair to go grey is still uncertain. 

Still, there is evidence that prolonged stress can damage both your mental and physical health. Visit the NHS Choices Moodzone for more information on stress and methods you can use to relieve or reduce your stress levels.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. 

Links To The Headlines

Could your job be making you grey? Stress can make hair colour disappear, say scientists. Daily Mail, June 11 2013

Stress is to blame for grey hairs. The Daily Telegraph, June 11 2013

Going grey? It’s fifty shades of stress. Daily Express, June 11 2013

Links To Science

Chou WC, Takeo M, Rabbani P, et al. Direct migration of follicular melanocyte stem cells to the epidermis after wounding or UVB irradiation is dependent on Mc1r signalling. Nature. Published online June 9 2013

"Headers can damage a footballer's brain, study finds," is the worrying warning in The Daily Telegraph. Football is one of the world's biggest participation sports, so it's important to know if it has any adverse health consequences. Fortunately for budding Rooneys and Ronaldos, the risks of heading balls may have been hyped in the headlines.

The news is based on a US study that tested whether regular "heading" of a football led to brain changes that could indicate traumatic brain injury, a type of injury usually only seen after a severe blow to the head.

Researchers gave 37 amateur players advanced brain scans that can detect changes in the brain's white matter. They also carried out neurological tests and asked players how often they thought they headed the ball.

The researchers found that more heading was associated with changes similar to those seen in people who suffered traumatic brain injury. Heading was also associated with poorer memory scores.

Despite these results, there is no evidence of a direct casual link between headers and brain damage. The people in the study were only tested at one point in time, so it is uncertain if the current findings represent any new changes, or if the players already had poor memories or abnormal white matter.

Any potential risk of brain injury has to be balanced against the wide range of health benefits from playing football regularly.

Where did the story come from?

The study was carried out by researchers from Albert Einstein College of Medicine of Yeshiva University, US. The US National Institutes of Health and the US National Institute of Neurological Disorders and Stroke funded the study, which was published in the peer-reviewed online edition of the science journal Radiology.

In general, the media headlines that suggest that heading a football can leave you with traumatic brain injury and memory loss are rather alarmist, and do not take account of the important limitations of this small cross-sectional study.

A number of papers highlighted the case of West Bromwich Albion legend Jeff Astle, who died at the age of 59 from a degenerative brain disease. A coroner attributed this disease to many years of heading footballs. However, as the Daily Mirror rightly points out, footballs were much heavier during Astle's playing career (1959-77) than they are now.

What kind of research was this?

This was a cross-sectional study examining the association between football heading and evidence of brain changes that indicate traumatic brain injury.

The researchers say they chose to study footballers as football is one of the most popular sports worldwide and it is unclear whether repetitive heading of the ball causes permanent damage.

This type of research can only indicate possible associations between lifestyle factors (such as heading footballs) and health outcomes (such as brain changes). However, it cannot establish cause and effect.

To reliably assess the effects, researchers would need to regularly image players' brains – with the first assessments ideally before they started playing football – and follow them up over time to see how any changes are related to objective assessments of the number of headers the players had made.

However, for several reasons – including cost (MRI scans are expensive to carry out) – a prospective cohort study is unlikely to be feasible. 

What did the research involve?

Thirty-seven football players (28 men and nine women; median age 31 years) were recruited from amateur football leagues in New York City. The players completed a questionnaire that asked them to estimate the amount of footballs they had headed in the previous 12 months. This was so the researchers could rank them into "exposure" groups in order to compare levels of exposure and any related abnormal brain changes. They categorised exposure as:

• low exposure (≤276 headings per year) – nine people
• medium exposure (277-1,095 headings per year) – 19 people
• high exposure (≥1,096 heading per year) – nine people

The questionnaire also asked whether the players had experienced one or more concussions in their lifetime. To determine this, participants were asked a series of questions about any previous head trauma for which they had tried to receive, had received, or were recommended to receive medical attention.

Each player underwent neurological tests supervised by a neuropsychologist to test their:

• psychomotor speed (a measurement of the relationship between brain function and physical movement)
• attention
• executive function (such as planning)
• memory

Finally, the players underwent a brain imaging technique called diffusion tensor imaging (DTI). DTI is a specialised type of MRI scan that the researchers used to detect any abnormal changes to the structure of the brain, including evidence of any prior trauma (such as signs of small bleeds).

DTI assesses the movement of water molecules with and along the nerve fibres that make up the brain's white matter. The researchers say the DTI imaging technique allowed them to measure the "uniformity of water movement (called fractional anisotropy, or FA) throughout the brain". They say abnormally low FA within white matter has previously been associated with cognitive impairment in people with traumatic brain injury.

Associations between heading and abnormal brain changes were then determined using statistical analyses.

What were the basic results?

The participants reported having played football for an average of 22 years and an average of 10 months during the previous 12 months.

In total, they reported heading a football between 32 and 5,400 times (median 432 times) in the previous 12 months.

The main findings of the research were:

• there were no signs of structural abnormality or bleeds identified among any of the participants
• greater heading exposure was associated with significantly lower fractional anisotropy (FA) at three regions in the brain diffusion tensor imaging – the threshold for the amount of headings and an association depended on the region of the brain the changes were seen in (range of heading thresholds was 885-1,550)
• there was a significant association between heading exposure and memory function, with an association threshold of 1,800 headings per year identified
• there was no association between heading exposure and neurological tests, other than memory
• reported concussions over the participants' lifetime and other demographic details were not significantly associated with either brain matter changes or neurological performance

The researchers say these findings are consistent with findings from another study of people with traumatic brain injury.

How did the researchers interpret the results?

The researchers conclude that heading a football is associated with abnormal changes to the white matter (nerve fibres) of the brain, as well as poorer neurocognitive performance. They say this relationship is not explained by a history of reported concussion.

Discussing the study's findings, lead researcher Dr Michael Lipton said: "Our study provides compelling preliminary evidence that brain changes resembling mild traumatic brain injury are associated with frequently heading a soccer ball [football] over many years."

Conclusion

Overall, this research provides no evidence that there is a direct cause and effect between repeated heading of a football and traumatic brain injury. However, there are several important limitations to this study that are worth noting.

One-off tests and scans of players

The people in the study only had brain images and neurological tests at one point in time, and were asked about heading in the previous year and if they had any concussions in their lifetime.

Without having the imaging and neurological tests prior to the year in question – or preferably in early periods of life, before they started playing football – we don't know whether the current findings represent any new changes.

It could be that the white matter always looked the way it did on imaging, or has done so for a long period of time. As such, the study does not prove that one causes the other – there may have been other factors at play not identified in this research that caused the brain changes seen.

Small study sample size

This was a very small study, with only 37 amateur football players participating. Larger prospective studies involving repeat brain imaging and neurological tests from a much larger number of people from more than one area are needed to draw further associations. It would also be interesting to test professional footballers, who are likely to head the ball more but use a better technique.

Amount of heading was self-reported

Heading was determined by self-reporting, and it is possible participants did not accurately report how often they headed the ball in the previous 12 months. This can make the results less reliable. In the rush and confusion of a football match, are players really going to accurately remember how many times they have headed a ball?

Lack of information on heading

The research did not take into account different types of headers, considering the speed, velocity and site of impact. These are all important factors when looking at the repetitive nature of heading.

Real-world outcomes for players

We don't know whether the observed brain structure and memory test performance actually had a significant impact on the person in terms of their everyday life and functioning. 

Overall, it is plausible that repeated minor impacts to the head may be associated with changes to the brain similar to those seen in people with traumatic brain injury. However, on its own this small study does not provide proof that heading a ball directly causes brain injury.

On a more positive note, we know regular exercise (such as playing football) can help lower blood pressure and cholesterol levels, which in turn can reduce the risk of heart disease and stroke. These benefits have to be weighed against any theoretical risk of memory problems caused by frequently heading a ball.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Headers can damage a footballer's brain, study finds. The Daily Telegraph, June 11 2013

Footballers can suffer brain damage and memory loss by heading a ball. Daily Mirror, June 11 2013

Footballers beware: Heading a ball can cause traumatic brain injury, research reveals. Daily Express, June 11 2013

Links To Science

Lipton ML, Kim N, Zimmerman ME, et al.Soccer Heading Is Associated with White Matter Microstructural and Cognitive Abnormalities. Radiology. Published online June 11 2013

“North and South health divide: Chilling study reveals premature death is 'postcode lottery',” the Daily Mirror reports.

The news is based on a new interactive map showing the variation in premature death rates across England.

The Longer Lives map, created by the new organisation Public Health England, ranks 150 local authorities by their premature death rates (deaths occurring before age 75).

The interactive map also enables users to compare these areas by five common causes of premature (and potentially preventable) deaths:

• cancer
• heart disease
• stroke
• lung diseases, such as chronic obstructive pulmonary disease 
• liver diseases such as cirrhosis

The simple, colour-coded map enables users to see the variations between each local authority at a glance, including a measure of socioeconomic deprivation.

Much of the media coverage of the new map was dominated by the striking contrast between large parts of the north, coloured red (poor health), and the affluent south, mostly coloured green (good health). However, there are also pockets of poor health in some southern cities, boroughs of London, and in the Midlands.

What information is this map based on?

The information provided in Longer Lives is from the Public Health Outcomes Framework. This uses records of deaths from the Office of National Statistics.

The death rates are standardised to account for the fact that death rates are higher in older populations and adjusts for differences in the age make-up of different areas.

What factors could explain the variations?

Links To The Headlines

Early deaths: Regional variations 'shocking' – Hunt. BBC News, June 11 2013

Councils should look at banning fizzy drinks in schools, says Health Secretary. The Daily Telegraph, June 11 2013

The health gap: New mortality rates show how the north loses out to the south. The Independent, June 11 2013

Steer clear of Manchester to avoid an early grave: City has highest rate of people who die prematurely. Daily Mail, June 11 2013

North and South health divide: Chilling study reveals premature death is 'postcode lottery'. Daily Mirror, June 11 2013

Early Death Atlas Shows 'Shocking' Variations. Sky News, June 11 2013

Most deaths in under-75s are potentially avoidable, says health body. The Guardian, June 11 2013

Want a long life? Live in the south of England. Metro, June 11 2013

"Speed cameras 'increase risk of serious or fatal crashes','' the Daily Mail tells us, while The Guardian, covering the same report, says "Speed cameras reduce serious road accidents." So you could be forgiven for being more than a little confused.

So what is the picture – do they increase or decrease injuries and fatal crashes?

The main objective of the report published last month by the RAC Foundation was to provide guidance on how speed camera data (which has been publicly available since 2011) should be analysed and interpreted. And not, despite the media’s take on the report, to provide simple figures on the number of collisions and fatalities in the vicinity of each camera.

For this reason, the report mostly consists of detailed discussion into statistical analysis and not real-world outcomes. Though it did provide some data for nine local authorities and road safety partnerships.

The figures for the nine regions reviewed present somewhat mixed results.

Five of the regions showed significant decreases both in the number of fatal or serious collisions (FSCs – decreases ranging from 24–53%), and collisions resulting in personal injury of any severity (PICs – decreases ranging from 20-32%) following introduction of cameras.

However, four of the regions did not find the introduction of cameras to have had a significant effect on FSCs and PICs.

Based on the data provided for the regions studied, we can only conclude that speed cameras have helped to reduce the number of collisions resulting in fatality or injury in some areas. But that in other areas they have had no significant effect.

However, no evidence is presented here to suggest they increase the risk of fatality or injury as was reported in some sections of the UK media.

Who produced the report and what evidence did it look at?

The report, published last month, titled "Guidance on the use of speed camera transparency data" was conducted by the Royal Automobile Club (RAC) Foundation and authored by Richard Allsop, Professor of Transport Studies, of University College London.

The RAC Foundation is a charity focusing on road safety and transport issues.

The report says that since Summer 2011, data relating to fixed speed cameras has been made available to the public and is presented on the websites of local authorities or road safety partnerships. A list of these websites can be found through on the Department for Transport.

Available data contains information for the period 1990 to 2010 on the number of collisions and casualties near each camera, typically on a 0.4 km to 1.5 km section of road. The RAC have used this information to find, for each camera, the year by year numbers of:

• fatal or serious collisions (FSC)
• number of people killed or seriously injured (KSI) in the FSCs
• collisions resulting in personal injury of any severity (PIC)
• number of casualties of all severity (CAS) in the PIC

Information is also available from websites regarding:

• observations of the speed of traffic near the camera on certain dates
• the numbers of offences detected by the cameras and actions taken in respect of the offenders

However, these things were not the focus of this report.

The RAC Foundation considered that the general public needed guidance on how to interpret this data, and this was the focus of the report. The Foundation downloaded data from nine local authorities and road safety partnerships and conducted statistical analysis before submitting their findings for independent peer review. The nine areas covered a mix of metropolitan and shire counties, including Warwickshire, Lincolnshire, Merseyside and Sussex.

The focus of this report was to "discuss a number of ways in which the data can be analysed, and provide users of the data [with] practical advice on the scope and nature of the available data and on their analysis and interpretation". It was not, as the media implied, to produce simple figures on collision and fatality rates.

The hope is that once an agreed method of analysis is reached, simple figures on collision and fatality rates, will be made available.

What were the main findings of the report?

The report initially raises several practical difficulties of examining the data:

• asking holders of data to make them available in a recommended form does not necessarily result in the data being made available in that form or at all
• websites and their addresses often change, so any central source of such addresses needs to be robust with respect to such changes
• users will want to work with data, not just read information on a screen or printout, so data should be mounted in a format that enables use with minimum transcription, that is in a spreadsheet or analogous format
• while users should of course be free to make their own analyses and interpretations of data that is made available, this can be helped by objective and non-directive advice about the nature and characteristics of the data concerned and pointers towards available techniques that are appropriate for application to data of that kind

The focus of their report is a fairly complex discussion of how to statistically interpret the data and look at how number of collisions in the vicinity of one camera relates to those in the whole partnership areas, and how numbers of FSC, KSI, PIC and CAS relate to each other.

Since the media focus is on changes in the numbers of collisions and fatalities, below is some of the data presented in appendices.

The following regions demonstrate significant decreases in PICs and FSCs since camera establishment:

• 24 cameras in Warwickshire showed a 25% decrease in the number of PICs and 38% decrease in the numbers of FSC in the vicinity of cameras since their establishment. In the three years prior to cameras in this area, PICs had been rising by 14% and FSCs rising by 57%
• 15 cameras in Leicester, Leicestershire and Rutland showed a 28% decrease in the number of PICs and a 53% decrease in FSCs since camera establishment. In the three years prior to cameras in this area, PICs had been rising by 14% and FSCs decreasing by 1%
• 42 cameras in Staffordshire and Stoke on Trent (an area of fewer crashes) showed a 32% decrease in the number of PICs and 44% decrease in FSCs since camera establishment. In the three years prior to cameras in this area PICs had been decreasing by 3% and FSCs decreasing by 1%
• 26 cameras in Staffordshire and Stoke on Trent (an area of more crashes) showed a 23% decrease in the number of PICs and 29% decrease in FSCs since camera establishment. In the three years prior to cameras in this area PICs had been decreasing by 13% and FSCs decreasing by 29%
• 55 cameras in Sussex showed a 21% decrease in the number of PICs and 36% decrease in FSCs since camera establishment. In the three years prior to cameras in this area, PICs had been increasing by 11% and FSCs increasing by 30%
• 203 cameras in Thames Valley showed a 20% decrease in the number of PICs and 24% decrease in FSCs since camera establishment. In the three years prior to cameras in this area PICs had been increasing by 3% and FSCs decreasing by 2%

Three of the remaining regions showed non-significant changes:

• 47 cameras in Cambridgeshire and Peterborough showed a 1% increase in the number of PICs since camera establishment (though a 42% drop in FSCs)
• 50 cameras in Lincolnshire showed a 9% decrease in the number of PICs and 15% decrease in FSCs since camera establishment
• 33 cameras in Merseyside showed an 11% increase in the number of PICs and 5% increase in FSCs since camera establishment
• 56 cameras in South Yorkshire showed a 1% increase in the number of PICs and 16% decrease in FSCs since camera establishment

How accurate was the media coverage?

In general, the media's coverage of this report was rather confusing and contradictory.

It appears the media wanted to report on the extent to which speed cameras decrease – or increase – the number road collisions and fatalities.

However, this wasn’t the objective of this report, which was a lot more complex, and focused on guiding people in how to interpret available data on speed cameras. 

The Daily Mail’s coverage of the report was particularly poor and arguably disingenuous. The claim that “Speed cameras increase the risk of serious or fatal accidents” is simply not backed up by the data.

The Mail seems to be resorting to what, in academic circles, is known as cherry picking – that is, focusing on the data that supports your argument while ignoring the data that doesn’t.

It was the case that at 21 camera sites the number of accidents went up – though whether this was due to speed cameras remains unproven. Leaving that issue aside, the Mail ignores any data from the remaining 530 camera sites where the number of accidents and fatalities went down.

Such a distortion of evidence is disturbing.

Based on the data provided for the regions studied here we can only conclude that speed cameras have helped to reduce the number of collisions resulting in fatality or injury – or that in some areas they have had no effect. However, no evidence is presented here to suggest that they increase them.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Speed cameras 'increase risk of serious or fatal crashes': New RAC investigation raises doubts over their usefulness. Daily Mail, June 7 2013

Reality check: do speed cameras reduce serious road accidents? The Guardian, June 7 2013

Speed cameras cut deaths and serious injuries "by more than a quarter". The Daily Telegraph, June 7 2013

Speed cameras cut car crashes by more than a quarter, research reveals. Daily Mirror, June 7 2013

Speed cameras ‘increase risk of serious car crashes’ in some areas, RAC claims. Metro, June 7 2013

The Mail Online has encouraged readers to "ditch the hand dryers", as "paper towels are more hygienic". The debate on the relative merits of paper towels versus hot air dryers may appear trivial, but the issue can be a matter of life and death.

Hand drying is an essential part of the hand washing process, as wet skin helps spread bacteria. In environments where people are vulnerable to the effects of infection, such as hospitals, thorough hand washing and drying could save lives.

The Mail reports on a review of 12 studies looking at how hygienic different hand drying techniques are. To borrow a pun from the Mail, it looks like paper towels win "hands down".

The review found the advantages of paper towels include that they dry the hands more quickly, remove more bacteria and are less likely to lead to cross-contamination. However, the review's authors did not include details of the methods used in the studies involved, so it is difficult to assess how valid their results are.

Unfortunately, we usually don't have much choice about the type of drying method we use in public or workplace bathrooms. The most important thing to remember is that whatever drying facilities are provided, it is just as important to dry your hands thoroughly as it is to wash them thoroughly with soap.

Where did the story come from?

The study was carried out by researchers from Queensland University of Technology and other organisations in Australia and China. No funding source was reported.

It was published in the peer-reviewed medical journal, Mayo Clinic Proceedings.

Mail Online covered this review reasonably well, although the limitations of the review were not mentioned.

As an aside, the study is actually from 2012, so it is a little puzzling why it is hitting the headlines now.

What kind of research was this?

This was a narrative review of the evidence on the effectiveness of hand drying techniques to prevent the spread of bacteria. The review included studies published since the 1970s.

Bacteria is more likely to be passed from wet skin than dry skin, making proper hand drying an essential component of the hand washing process in order to prevent the spread of infections.

This prevention of the spread of infection is especially important in settings such as hospitals and clinics. The authors sought to identify the most effective drying technique and make recommendations on its use for healthcare professionals.

What did the research involve?

The study authors searched several databases for studies that compared at least two hand drying methods and reported results on different aspects of hand drying effectiveness. The various factors considered were:

• amount of water removed
• effectiveness of removal of bacteria
• prevention of cross-contamination

The authors compared several techniques, including paper towels, cloth towels, electric hot air dryers, jet air dryers and evaporation (air drying).

This was a narrative review, so the authors didn't statistically pool the study results as would be the case with a meta-analysis. Based on the analyses presented in each identified study, the researchers are able to suggest how the various techniques compare. However, they did not provide a pooled statistical estimate of effectiveness for each technique.

What were the basic results?

The researchers identified 12 articles that were included in the review.

Drying effectiveness

Two studies assessed how efficiently different methods removed water from the hands. The authors report that:

• one study compared cloth towels with hot air dryers and found that 10 seconds of drying with a cloth towel was approximately equivalent to 45 seconds of using a hot air dryer
• the other study found that 10 seconds of drying with either paper towels or jet air dryers was equally efficient at removing water, while hot air dryers took about 40 seconds to achieve the same level of dryness

Bacteria removal and drying method

Seven studies assessed the effectiveness of different techniques of removing bacteria from the hands and reported inconsistent results.

One study found that paper towels reduced the number of all types of bacteria, air dryers increased their number, while jet air dryers increased the number of some, but not all bacteria. The increases seen from jet air dryers were less than those seen with hot air dryers.

Another study found that hot air dryers were the least effective method of removing bacteria.

Two studies that looked at various drying methods reported no difference in the amount of bacteria left on the hands.

Another study reported that using a hot air dryer with ultraviolet light for 30 seconds was more effective than paper towels, but that rubbing the hands together under a hot air dryer was less effective.

However, a final study reported that 10 seconds of holding the hands still under a hot air dryer was better at removing rotaviruses and E. coli than 10 seconds using either paper or cloth towels.

Bacteria removal and drying technique

One study found that 10 seconds of using a hot air dryer was associated with more bacteria on the hands than not using a dryer at all. It found that rubbing the hands together under a hot air dryer prevented bacteria removal. Using a jet air dryer for 10 seconds was found to be more effective at removing bacteria than using a hot air dryer for 30-35 seconds. This study also reported that using a paper towel was the best method of removing bacteria, especially from the fingertips.

One of the studies found that rubbing the hands together under a hot air dryer for 15 seconds significantly increased the amount of bacteria on the hands, while holding the hands still under the dryer for the same amount of time decreased the amount of bacteria, although it's not clear whether this was significant. This study also found that paper towels were more effective at removing bacteria from the fingertips than from the palm of the hand and fingers.

Preventing cross-contamination

When examining the effect of the methods on bacterial transmission or cross-contamination, the researchers found one study that investigated the risk of cross-contamination in a hospital setting. It compared the spread of bacteria using a hot air dryer versus using paper towels and found that the electric dryers spread the bacteria up to three feet (about a metre) from the unit, while no dispersal was found when using paper towels.

A second study reported that hot air dyers led to a large number of airborne bacteria near the dryer, but no such spread was seen with either paper or cloth towels.

A third study found that jet air dryers in a washroom were found to spread bacteria up to two metres (around six feet), while paper towels and hand dryers were better at not contaminating the washroom.

How did the researchers interpret the results?

The authors concluded that, "From a hygiene viewpoint, paper towels are superior to electric air dryers" and that, "drying hands thoroughly with a single-use, disposable paper towels is the preferred method of hand drying in healthcare".

Conclusion

This review suggests that using paper towels to dry the hands is more effective than other methods at actually getting the hands dry, reducing the amount of bacteria on them, and preventing contamination of the washroom environment.

There are, however, limitations to this review that should be considered before concluding that hot air dryers or jet dryers are ineffective:

• The review did not report the quality of the various studies included. When determining whether the results of a study are valid, it is important to establish whether the research methods were sufficient to minimise bias and confounding. As the review did not report this, it is unclear how valid the studies' results are.
• The studies' methods varied and this could influence the consistency of results across the experiments. The amount of time spent drying, the method of measuring bacteria levels and other differences may account for the variation in results.

Identifying hygiene behaviours to help minimise the risk of cross-infection has become increasingly important. Much research has gone into the most effective hand washing techniques. The good news is that, whatever the limitations of the review, its findings support current hand washing recommendations.

This review suggests that paper towels are the best option for settings where containing infections is critical, and may be more effective than hot air dryers.

However, if you have no choice – as is the case in most public toilets and workplace washrooms – and only hot air dryers are provided, take extra time to dry your hands thoroughly. There is little evidence that they are any worse than hand towels, other than the extra time spent drying your hands.

There is some sensible advice for doctors on how they should wash their hands contained in NICE guidelines on infection control. You may want to make sure that your doctor or nurse knows about, and follows, this advice.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Ditch the hand dryer: Paper towels are more hygienic because they remove more germs. Mail Online, June 4 2013

Links To Science

Huang C, Ma W, Stack S. The Hygienic Efficacy of Different Hand-Drying Methods: A Review of the Evidence. Mayo Clinic Proceedings. Published online June 1 2012

“Veg diet key to living longer,” reports today’s Daily Express front page headline.

Its story is prompted by a large, well-designed, long-term study into vegetarian dietary patterns and their effects on reported mortality (death). The main finding was that vegetarians had a 12% reduction in the risk of death from any cause compared with non-vegetarians.

However, the researchers’ definition of ‘vegetarian’ was quite broad and may horrify some vegetarians as it included people who ate meat and fish once a week or less. Dietary patterns were only measured at the start of the study, and these can change over time. The study also had a relatively short follow-up to determine whether dietary patterns might affect the risk of death.  

It’s also worth noting that vegetarians tended to live healthy lifestyles, and this could have influenced the results.

While this study cannot show direct cause and effect between diet and death risk, it highlights an important point. Even if you do not want to stop eating meat there is plenty you can ‘borrow’ from the ‘vegetarian lifestyle’ to improve your health, such as eating plenty of fresh fruit and vegetables.

Where did the story come from?

The study was carried out by researchers from Loma Linda University, California and was funded by the US National Cancer Institute and National Institute of Food and Agriculture. It was published in the peer-reviewed journal, JAMA Internal Medicine.

The results of the research were generally well covered in the media. However, the Mail Online website presented speculation as fact in its headline: it states that people who avoid meat have better health due to low blood pressure. Although this is a possible and plausible explanatory factor, the current study did not investigate the blood pressure of vegetarians.

What kind of research was this?

This was a prospective cohort study set in the US that aimed to evaluate the association between vegetarian dietary patterns and mortality (death).

A cohort study is the ideal study design to address this question. However, cohort studies cannot show cause and effect, as it is possible that other factors (confounders) are responsible for the associations seen. Ideally, the effects of a particular diet on a clinical outcome would be assessed through a randomised controlled trial. However, this is unlikely to be feasible when investigating an outcome such as mortality, which would need a long duration of follow-up; and also it would be difficult to randomise people to eating meat, or not eating meat, which comes down to personal choice.

What did the research involve?

The diet of 73,308 men and women participating in the Adventist Health Study 2 was assessed. The Adventist Health Study 2 is an ongoing cohort study involving members of the Seventh Day Adventist church (a Christian denomination) where the promotion of a healthy diet and lifestyle is a tenet of Adventist teaching.

The people’s diets were assessed when they entered the study (between 2002 and 2007) using a food frequency questionnaire. Based on the results of the questionnaire, the participant’s diet was classified into one of five dietary patterns:

• non-vegetarian (ate fish and meat more than once per week)
• semi-vegetarian (ate fish and meat but not more than once per week)
• pesco-vegetarian (ate seafood at least once per month but all other meats less than once per month)
• lacto-ovo-vegetarian (consumed dairy and egg products but fish and all other meats less than once per month)
• vegan (consumed eggs, dairy, fish and all other meats less than once per month)

For some analysis, vegan, lacto-ovo-vegetarian, pesco-vegetarian and semi-vegetarian were combined as “vegetarian”.

Deaths that occurred up until the end of 2009 were identified from the US National Death Index.

The researchers analysed the relationship between vegetarian dietary patterns and all-cause and cause-specific mortality.

What were the basic results?

During a mean (average) follow-up of 5.79 years there were 2,570 deaths.

The results were adjusted for the following confounders:

• age
• gender
• race
• smoking status
• exercise
• income
• education
• marital status
• alcohol intake
• geographical region
• amount of sleep per night

After adjustments, vegetarians (all vegetarians combined) had a 12% reduction in the risk of death from any cause compared with non-vegetarians (hazard ratio (HR) 0.88, 95% confidence interval (CI) 0.80 to 0.97).

Vegetarians also had a reduced risk of death from causes other than cardiovascular disease or cancer (HR 0.85, 95% CI 0.73 to 0.99). More specifically, vegetarians had a reduced risk of death from kidney problems and deaths from hormonal (endocrine) problems. Male vegetarians only also had a significantly reduced risk of death from ischaemic (coronary) heart disease and from cardiovascular disease overall.

The different classes of vegetarians were then considered separately. The researchers found that compared to non-vegetarians:

• Pesco-vegetarians had a significantly reduced risk, in both sexes combined, of death from any cause (HR 0.81, 95% CI 0.69 to 0.94), death from ischaemic heart disease (HR 0.65, 95% CI 0.43 to 0.97) and non-cardiovascular, non-cancer death (0.71, 95% CI 0.54 to 0.94).
• Lacto-ovo-vegetarians had a significantly reduced risk in both sexes combined for all-cause mortality (HR 0.91, 95% CI 0.82 to 1.00).
• Vegans had a significantly reduced risk, in both sexes combined, of deaths from non-cancer, non-cardiovascular causes (HR 0.74, 95% CI 0.56 to 0.99).

When men and women were examined separately, reductions in risk were larger and more often significant for men than for women.

How did the researchers interpret the results?

“Vegetarian diets are association with lower all-cause mortality and with some reductions in cause-specific mortality. Results appeared to be more robust in males. These favourable associations should be considered carefully by those offering dietary guidance.”

Conclusion

This large, well-designed cohort study has found an association between vegetarian dietary patterns and reduced risk of death.

This study has the advantage that it included a large number of participants consuming various diets.

However, as this study is a cohort study, it cannot show cause and effect, as it is possible that other factors are responsible for the associations seen. Although the researchers adjusted for many of these factors, it was found that the vegetarian groups tended to be older, more highly educated and more likely to be married, to drink less alcohol, to smoke less, to exercise more and to be thinner. The reduced risk of death may be due to other lifestyle factors of vegetarians rather than diet.

In addition, the study has some other limitations, which were pointed out by the researchers:

• The study had a relatively short follow-up. Although the average follow-up was almost six years, this is quite short to address how dietary patterns might affect the risk of death.
• Dietary patterns were only measured at baseline, and it is possible that dietary patterns change over time.
• The researchers included in the ‘vegetarian’ category people who eat fish and meats, but not more than once per week. This is not what a vegetarian diet is traditionally taken to mean.

This study was also conducted in a select population sample of Seventh Day Adventists, who have particular health and lifestyle characteristics. They tend to be much healthier than the population at large (for example, smoking and alcohol are discouraged among Adventists), and enjoy a greater average life expectancy.

This may mean that the differences observed between vegetarians and non-vegetarians in this study may differ from what would be observed in study of other population samples.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Vegetarian diet could cut early death risk. Daily Express, June 4 2013

Are vegetarian diets secret to long life? Mail Online, June 4 2013

Links To Science

Orlich MJ, Singh PN, Sabaté J, et al. Vegetarian Dietary Patterns and Mortality in Adventist Health Study 2. JAMA Internal Medicine. Published online June 3 2013

'Just 12 minutes of intensive exercise per week is enough to improve your health if you are overweight,' according to The Daily Telegraph. The paper reports on the findings of a study into the phenomenon of high-intensity interval training (HIIT). It's claimed that HIIT can deliver many of the benefits of conventional exercise in a much shorter time.

Two groups of overweight and inactive, but otherwise healthy, middle-aged men either followed a programme of:

• four bursts of intense exercise for four minutes, each separated by three minutes of lower intensity exercise, three times a week (plus a 10-minute warm-up and a five-minute cool-down), or
• a single burst of intense exercise for four minutes, three times a week (plus the warm-up and cool-down)

After 10 weeks, both groups had improved their bodies' maximal oxygen uptake (a measure of fitness) and lost weight.

This suggests that in healthy overweight men, a regular programme based on a single burst of intense exercise may bring similar fitness benefits to a programme involving repeated bursts of intense exercise.

However, this was a very small and relatively short-term study. Ideally, larger studies are needed to explore the longer term effects of this type of exercise programme in more diverse groups of people.

HIIT may not be safe for everyone, especially if you have health problems or are not currently doing any exercise. Check with your GP first.

Where did the story come from?

The study was carried out by researchers from the K.G. Jebsen Center for Exercise in Medicine in Norway, and other research centres in Norway, Canada and the USA. It was funded by the K.G. Jebsen Foundation, the Norwegian Council of Cardiovascular Disease, the Norwegian Research Council, St Olav's University Hospital, Norway, and the Eckbos Foundation.

It was published in the peer-reviewed open access medical journal PLoS ONE.

The Telegraph and Mail Online website reported this study quite accurately, but both suggested that the single burst of exercise group did just 12 minutes of exercise per week. In fact, including the warm-up and cool-down sessions, they actually did 57 minutes of exercise per week.

What kind of research was this?

This was a randomised controlled trial (RCT) looking at the effects of regular short bursts of intensive endurance training on fitness.

Current official guidelines in the UK recommend that healthy adults should do:

• at least 150 minutes per week of moderate intensity aerobic exercise a week, or
• 75 minutes of vigorous exercise a week, with an equivalent mix of moderate- and vigorous-intensity aerobic activity every week (for example, two 30-minute runs plus 30 minutes of fast walking)

Doing muscle-strengthening activities on two or more days is also recommended. Read more about the physical activity guidelines for adults.

Many people find that even though they want to get fitter through exercise, it can be difficult to find the time. In the current study, researchers wanted to assess the effects of two shorter, high-intensity exercise programmes on fitness levels.

This type of study is the best way of comparing two different treatments or interventions, as the groups should be well balanced at the start of the trial. This means any differences at the end of the trial can be attributed to the intervention received.

What did the research involve?

The researchers enrolled 26 overweight men (BMI between 25 and 30) who were healthy but inactive. They were aged 35-45 and had not exercised regularly for at least two years prior to the study. Men with heart problems, lung disease, high blood pressure, kidney failure, or orthopaedic or neurological problems were not eligible to participate.

The men were randomly assigned to do one of two exercise programmes on an inclined treadmill three times a week for 10 weeks. One programme involved a single four-minute intense period of exercise (single burst group), and the other consisted of four bouts of four minutes' intense exercise separated by three minutes of "active recovery" (multiple burst group). The researchers say that each burst was the equivalent of a four-minute quick walk uphill at an 8-10% gradient, or rapidly walking up six to 10 flights of stairs.

Before both types of sessions, the men warmed up for 10 minutes by walking, jogging and running on an inclined treadmill with the aim of reaching 70% of their maximum heart rate. During the four-minute intense parts of their exercise, they aimed to reach 90% of their maximum heart rate.

The men whose programme included active recovery periods aimed to reach 70% of their maximum heart rate in these periods. Both groups of men also had a five-minute cool-down session at the end of their workout. Overall, the groups did 19 minutes (single burst group) and 40 minutes (multiple burst group) of exercise in total.

The researchers took various measures of fitness and cardiovascular risk. The main outcome they were interested in was the men's maximal oxygen uptake (VO2max), which is the maximum amount of oxygen they could consume each minute per kg of bodyweight while doing exercise. A higher VO2max indicates a higher level of fitness, and previous research has linked a higher VO2max measurement with a reduced risk of death. They also measured:

• blood pressure
• levels of fats, sugars and other substances in the blood
• body composition
• BMI

What were the basic results?

The group doing the single burst of intense exercise had slightly higher BMIs at the start of the study (average BMI 27.8 compared with 27.0 in the multiple burst group). Two men in this group dropped out of the study – one because of back pain and one because he moved out of the area – and were not included in the analysis.

After the 10-week study period, the groups did not show statistically significant differences in change in any outcome. Both groups showed an increase in maximal oxygen consumption.

The single burst exercise group showed a 10% improvement, and the multiple burst group showed a 13% improvement. The difference between groups in this outcome did not quite reach statistical significance.

Both groups showed a reduction in weight: 1.8kg in the single burst group and 2.1kg in the multiple burst group. However, the researchers point out that short bursts of intense exercise are unlikely to achieve the kind of sustained weight loss needed to tackle obesity.

Fasting blood sugar level was also reduced in both groups. Blood pressure showed a statistically significant reduction in the single bout group, but not in the repeated bout group. Levels of one form of cholesterol (oxidised LDL cholesterol) showed a statistically significant reduction in the repeated bout group, but not in the single bout group.

How did the researchers interpret the results?

The researchers concluded that a single short bout of intense exercise performed three times a week "may be a time-efficient strategy to improve VO2max and reduce blood pressure and fasting glucose in previously inactive but otherwise healthy middle-aged individuals".

Conclusion

This small study has suggested that short periods of intense exercise can increase fitness to a similar level as sustained exercise, and show similar effects on outcomes such as weight. But this study has some limitations, including:

• The study was very small, involving just 26 men. This may mean that the results may not be as representative of the general population of similar men as a larger sample would be. It also means that it is less able to detect differences between the groups in their statistical tests, even if they exist.
• The study only included overweight but healthy men. The results may not apply to other groups of people.
• There was no group that didn't exercise at all or do less intensive exercise, so we can't tell what would have happened with these types of programmes.
• The study was only relatively short term and therefore could not look at long-term outcomes, such as whether weight loss was maintained or if there was an increased risk of heart attack.

Overall, the study suggests that fitness may be improved by regular exercise sessions that include a short, intensive bout of exercise. This may be encouraging for people who feel they don't have enough time to exercise. And for most people, some exercise is better than none.

However, it's important to note that the men in this study were healthy, with no heart disease, high blood pressure, or orthopaedic or lung problems. Short bouts of very intensive exercise may not be suitable for people who have these conditions.

It is always good to check with your GP if you are committed to getting fit but have been inactive for some time. Read more advice about starting a new exercise plan.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Twelve minutes' exercise per week 'enough to stay fit'. The Daily Telegraph, May 30 2013

Forget lengthy gym workouts: Just 12 minute of exercise a week can get couch potatoes fit. Mail Online, May 30 2013

Links To Science

Tjønna AE, Leinan IM, Bartnes AT. Low- and High-Volume of Intensive Endurance Training Significantly Improves Maximal Oxygen Uptake after 10-Weeks of Training in Healthy Men. PLos One. Published online May 29 2013