“Women who like a glass of wine after work are less likely to gain weight than those who stick to mineral water,” according to The Times, which claims that moderate female drinkers have a lower risk of obesity than teetotallers.

The research behind these claims asked a group of middle-aged American women of a healthy weight about their alcohol consumption. The women were sent follow-up questionnaires over the next 13 years to track how their weight changed. Over the course of the study most of the women gained weight but on average those who originally consumed at least four units per day gained around 2kg less than their non-drinking counterparts.

While this study has found that higher alcohol consumption was associated with slightly lower weight gain over time, there are a number of limitations to the research  Equally, the study did not look at potential mechanisms by which alcohol could have an effect on weight, although it suggests that drinkers may have replaced dietary calories with calories from alcohol. However, the negative health effects of regular alcohol consumption are well-known, and women are advised to limit alcohol consumption to two to three units per day.

Where did the story come from?

This research was conducted by Dr Lu Wang and colleagues from Brigham and Women’s Hospital and Harvard University. The study was funded by the US National Institute of Health and published in the peer-reviewed medical journal Archives of Internal Medicine.

Several newspapers have reported on this research, with some suggesting that alcohol may aid weight loss. However, the research did not directly prove that alcohol consumption prevents weight gain, instead showing that the dietary and exercise habits of drinkers versus non-drinkers differed. Some news sources also reported on a theory that alcohol may be broken down in the liver to create heat rather than fat. That theory was not tested by this research.

What kind of research was this?

This was a prospective cohort study following a group of American women of normal weight to look at how their drinking habits affected the likelihood of them becoming overweight or obese over time.

The researchers say that alcohol contains 7.1 calories per gram and that the extra calories it contributes to the daily diet may increase weight gain. They add that studies have not provided consistent evidence that alcohol consumption is a risk factor for obesity. The researchers therefore used data from a large prospective cohort study in women to see whether there was any association between alcohol consumption and obesity in women.

What did the research involve?

The researchers drew participants and data from the Women’s Health Study, a randomised clinical trial that evaluated the effects of low-dose aspirin and vitamin E in the prevention of cancer and cardiovascular disease. The trial involved 39,876 female healthcare professionals aged 39 to 89 who were free of cancer and cardiovascular disease. For this subsequent alcohol study the researchers included 19,220 women with a body mass index (BMI) ranging from 18.5 up to 25, which is considered to be within the healthy range.

At the start of the study the participants were given a questionnaire asking how many alcoholic drinks they consumed. The frequency was graded in nine possible responses that ranged from “never or less than once per month” to “more than six times a day”. Their alcohol consumption was calculated according to the alcohol content in each type of beverage. The researchers defined one alcoholic unit as containing 8g of pure alcohol.

At the start of the study the researchers also collected baseline information on each participant’s age, smoking status, physical activity level, menopausal status, postmenopausal hormone use, multivitamin use, history of diabetes, hypertension (high blood pressure) and high cholesterol levels. The participants also completed a food frequency questionnaire that assigned a portion size for each specified food item. These were used to calculate an estimate of each participant’s calorie intake.

Information on the participants’ body weights was updated using follow-up questionnaires given 2, 3, 5, 6 and 9 years after the first questionnaire. In addition 16,322 of the women agreed to be followed up for a further four years, providing a dataset spanning 13 years since the initial questionnaire.

The women had their BMI calculated and categorised as normal (18.5-25), overweight (25-30) or obese (over 30). If a participant became overweight or obese while being followed up, the year in which this event occurred was recorded. If a woman developed diabetes, the date of the diagnosis was also recorded.

When the researchers performed their initial analysis they only adjusted their data to account for the women’s ages. As additional factors may have affected the women’s weight the researchers made further adjustment to account for BMI at baseline, non-alcoholic energy intake and the type of food they ate (such as fruit and vegetables, meat, refined or whole grains, fibre and dairy produce). They also adjusted for the amount of exercise they did, their smoking status, hormone status, and any history of high cholesterol or high blood pressure.

What were the basic results?

The women’s baseline characteristics at the time of the first questionnaire showed that those who drank greater amounts of alcohol were more likely to be older, white, current smokers, postmenopausal, have high blood pressure and have a lower baseline BMI. They also found that although the total energy intake was greater in women who drank lots of alcoholic beverages, these women took in fewer calories from food than the non-drinkers.

Alcohol intake was associated with a greater intake of red meats, poultry and high-fat dairy products but a lower intake of whole grains, refined grains, low-fat dairy products, fats, carbohydrates and fibre. Women who consumed an intermediate amount of alcohol did more exercise than those who did not drink or drank greater amounts. On average, all women put on weight over the follow-up period. However, the greatest average weight gain was in the women who did not drink alcohol.

The drinking and non-drinking groups had varied in a number of dietary and lifestyle factors at the start of the study, leading the researchers to perform a set of analyses that were adjusted to account for the influence of these variations. After these adjustments, they found that the relationship between weight gain and low alcohol consumption was stronger.

The researchers also found that 41.3% of the women had become overweight or obese during the follow-up period. When using a BMI of 30 as a cut-off, 3.8% of the women had become obese. The mean weight gain during 12.9 years of follow up was 3.63kg for women who did not consume alcohol, compared to 1.55kg for those who consumed 30g per day or more. (95% confidence interval CI, was 3.45-3.80kg vs 0.93-2.18KG).

How did the researchers interpret the results?

The researchers concluded that light-to-moderate alcohol consumption was associated with less weight gain and a lower risk of becoming overweight/and or obese over 12.9 years of follow up in middle-aged women.

They suggested that other studies have shown that in British men, an equivalent increase in alcohol consumption was associated with increased BMI. They suggest that “male drinkers tend to add alcohol to their daily dietary intake, whereas female drinkers usually substitute alcohol for other foods without increasing total energy intake”.

Conclusion

This large cohort study that followed middle-aged women for almost 13 years found that there was an association between greater alcohol consumption and slightly slower weight gain over this period.

Despite the tone of press coverage, it should be remembered that this type of study can only show associations between factors, and cannot say how or whether alcohol directly causes the slower weight gain. There are also a number of limitations to this research, some of which the researchers have highlighted:

• The participants self-reported their weights and alcohol consumption, which may have resulted in a misclassification or underestimation of these values.
• The study used a single measurement of alcohol consumption taken at the start of the study. It is likely that the participants’ drinking habits changed over the 13-year study period.
• The questionnaire used in the study did not collect sufficient detail on some aspects of the the women’s drinking habits. For example, it did not differentiate between women who drank a small amount on most days of the week and those who drank multiple drinks on one day of the week. These drinking patterns may have different effects on the body’s metabolism.
• The women in this study were predominantly white, female healthcare professionals who may differ in their socioeconomic status from other women, so these findings may not apply to the population as a whole or to men.
• The women included in this study were all originally in the healthy BMI range. This means the study has not looked at how the weight of women outside this range changes in relation to alcohol intake or whether alcohol may have contributed to existing weight problems.
• The average difference in weight gain between the groups was relatively small, at just over 2kg.

Given the limitations of this research, it is not possible to say whether alcohol consumption directly reduces the chances of weight gain. However, the data from this study contributes to our understanding of how related lifestyle factors such as alcohol consumption and eating habits can contribute to weight gain.

Excessive alcohol consumption is known to be bad for our health in several ways. For example, it can increase the risk of cancer and depression. Women are recommended to drink no more than two to three units a day. The daily limit for men is three to four units.

Links To The Headlines

Wine doesn't make women fat, report claims. The Daily Telegraph, March 8 2010

Drink up girls: wine isn't fattening. The Times, March 8 2010

Cheers, girls! The odd glass of wine is less fattening than water. Daily Express, March 8 2010

Links To Science

Wang L, Lee IM, Manson JAE et al. Alcohol Consumption, Weight Gain, and Risk of Becoming Overweight in Middle-aged and Older Women. Arch Intern Med. 2010;170(5):453-461[Awaiting publication]

The Daily Telegraph has reported that “vitamin D 'triggers and arms' the immune system”. It said that researchers believe that vitamin D plays a key role in boosting the immune system.

The study looked at human T cells in the laboratory, and found that vitamin D was part of a complex process in which T cells become 'primed' and help to fight infection. While these findings suggest that people with vitamin D deficiency are more susceptible to infection or that vitamin D supplements might boost immunity, such theories need to be tested further before drawing any firm conclusions.

It is important to have enough vitamin D to maintain a healthy body. Vitamin D forms in our skin in response to sunlight. However, care should be taken to avoid burning or over-exposure. Vitamin D is also found in foods such as oily fish, eggs, fortified margarines, some breakfast cereals and vitamin supplements.

Where did the story come from?

Dr Marina Rode von Essen and colleagues from the University of Copenhagen and Bispebjerg Hospital in Denmark carried out this research. The study was funded by the Danish Medical Research Council, the Lundbeck Foundation, the Novo Nordisk Foundation, the King Christian the 10th Foundation and the A.P. Møller Foundation for the Advancement of Medical Sciences. Some of the chemicals used in the study were provided by the manufacturer Bayer Schering Pharma AG. The paper was published in the peer-reviewed scientific journal Nature Immunology.

The study was reported in The Daily Telegraph, Daily Mail, and Metro. The newspapers give reasonable coverage of this complex research. Metro includes the study’s sensible warning that sunburn should be avoided.

What kind of research was this?

This laboratory research investigated what happens to human T cells when they respond to foreign molecules (called antigens). T cells are immune-system cells that recognise antigens (for example molecules on the surfaces of viruses) and kill infected cells. In particular, the researchers looked at the 'priming' of the T cells, a process by which T cells prepare to respond to antigens. When exposed to an antigen, primed T cells are able to multiply in number faster and produce more chemicals to help promote further immune response than naive T cells. They looked at the role of a protein called phospholipase C, which is involved in sending signals within cells. They also looked at how vitamin D and the vitamin D receptor are involved in this process.

This type of laboratory study helps researchers to unravel the complex events that occur in individual cells in the immune system. A better understanding of how the immune system works could suggest ways of boosting immune responses. In this case, if vitamin D was found to play a role in the immune system, this would suggest that people with vitamin D deficiency might be more susceptible to infection or that vitamin D supplements might boost immunity. Such theories would have to be tested in human research before any firm conclusions could be drawn.

What did the research involve?

The researchers took 'naive' (unprimed by exposure to antigens) human T cells from freshly drawn blood and grew them in the laboratory. They grew some in solutions containing immune system molecules: conditions that 'primed' them for activation.

The characteristics and behaviour of the 'primed' T cells were then compared with the 'naive' T cells. This included the cells’ response to being 'restimulated' through re-exposure to the immune system molecules that originally primed their activation.

The researchers were especially interested in how much the cells produced a particular form of phospholipase C, called phospholipase C-γ1, and how this was linked to the presence of the vitamin D receptor. They also looked at what happened if they blocked the cells from responding to vitamin D. They carried out experiments to investigate how the cells switched on the production of the vitamin D receptor.

What were the basic results?

The researchers found that 'naive' T cells that had not been primed produced only a small amount of phospholipase C-γ1. However, following priming by exposure to the activator immune system molecules, the T cells began to produce far more phospholipase C-γ1. For this to occur, the T cells needed to be in the presence of vitamin D and the vitamin D receptor.

They also found that naive T cells did not produce the vitamin D receptors, and that these receptors were only produced when the T cells were primed.

How did the researchers interpret the results?

The researchers conclude that T cells produce vitamin D receptors when they are primed to respond to antigens. Vitamin D then acts via the receptor to stimulate production of phospholipase C-γ1. These changes are necessary for the T cells to be activated.

Conclusion

This research indicates that vitamin D is involved in the activation of the T cells of the immune system. It is important to note that this is a laboratory study, and it is useful in helping researchers to understand what happens in specific immune system cells when exposed to foreign entities such as bacteria or viruses. It does not tell us how variations in vitamin D levels might affect people’s susceptibility to infection, or what the ideal level of vitamin D is for supporting immune system responses to infection.

Other studies will no doubt look into these questions. However, as with other vitamins, it is clearly important to have sufficient vitamin D to maintain a healthy body. Vitamin D forms in our skin in response to sunlight, but care should still be taken to avoid burning or over-exposure. Vitamin D is also found in foods such as oily fish, eggs, fortified margarines, some breakfast cereals and vitamin supplements.

Links To The Headlines

How sunshine can help your body fight disease. Daily Mail, March 8 2010

Vitamin D 'triggers and arms' the immune system. The Daily Telegraph, March 8 2010

Sunshine linked to immune system boost. Metro, March 8 2010

Links To Science

Rode von Essen M, Kongsbak M, Schjerling P, et al. Vitamin D controls T cell antigen receptor signaling and activation of human T cells. Nature Immunology 2010; published online March 7 2010

Children’s eyes could be seriously damaged by capsules of laundry detergent, doctors have warned.

Capsules of concentrated detergent first went on sale in 2001, designed to be less messy and inconvenient than washing powders and liquids. However, hospital records suggest that curious children can be injured if they burst the brightly coloured sacks and release the cleaning agents inside.

In a letter to the British Medical Journal, ophthalmologists from the Western Eye Hospital, London, say that the corrosive substances in the cleaning capsules can cause severe burns if they get into the eyes of toddlers. The doctors reported that the capsules contribute to 40% of the chemical eye burns they treat infants for.

What did the report say?

The doctors say that detergent capsules were linked to 40% of the chemical eye injuries they treated in children under the age of five. The average age of those treated was two. The doctors also consulted Guy’s and St Thomas’ Hospital Poisons’ Unit in London, finding that it had received 192 enquiries in 2007-8 and 225 during 2006-7 relating to the capsules. One-fifth of these enquiries were related to children who had the detergent in their eyes.

Of the 13 children the doctors treated for detergent in their eyes, 12 experienced chemical burns to their cornea, the clear layer covering the iris and pupil. For these children, the lining of the cornea took up to three days to heal.

However, one child only had their eye washed with water on arrival at hospital. The child sustained total burns to the cornea in both eyes, taking the corneal lining seven days to heal.

What is the danger from these products?

According to the authors, detergent capsules contain concentrated alkaline solutions such as detergents that can cause severe chemical injuries to the eyes. They say that alkali burns are the most serious form of chemical injury to the eye, potentially causing irreversible damage that can have lifelong ramifications.

The brightly coloured contents and unusual texture of the capsules may also make them tempting playthings for exploring toddlers, who might burst them by squeezing them or placing them in their mouths. While other forms of cleaning product can also harm children, concentrated liquid capsules may be more likely to cause accidents than bottled or powdered detergents if left within a child’s reach.

What should I do if my child gets detergent in their eye?

If detergent gets into a child’s eyes, it is important to take action as soon as possible in order to limit further damage:

• Wash their eyes out under large amounts of cold, running water for at least 10 minutes.
• While washing, gently hold the eyelids open to help flush out as much of the detergent as possible.
• Seek medical advice promptly. You can call NHS Direct on 0845 4647.

Sterile saline solution can also be used to wash out the eyes, although it is unlikely to be available in most homes.

If the detergents are ingested (swallowed), parents should seek medical advice promptly.

How should I store these products if I use them?

Detergents and other cleaning products are often stored in cupboards under sinks, within easy reach of curious toddlers. Instead, store your products in a sealed container on a high shelf or within a childproof cupboard. Using baby safety gates to block doorways can also keep children out of the kitchen, where a high proportion of accidents occur.

Where can I get more advice on preventing and treating accidents?

Emergencies such as chemical burns to the eyes should always be referred to trained medical professionals. However, knowing how to prevent and deal with accidents are important skills to have and many organisations offer reliable advice for parents. More information is available at:

• NHS Live Well: first aid
• British Red Cross 
• Royal Society for the Prevention of Accidents (RoSPA)
• RoSPA Safe At Home