New research suggests that one -and only one- drink of alcohol a day could be good for the health of middle aged women. However, the implied benefits of alcohol are drawing some criticism from some experts.
US researchers have studied over 121,000 nurses enrolled in the US Nurses' Health Study which started in 1976. They compared the drinking habits of women when middle-aged with their later health status. The research suggests that women who had one standard drink of alcohol a day may be healthier than their peers who did not drink at all, who consume more than two drinks a day, or who consume four drinks or more at the one time.
The study, "Alcohol Consumption at Midlife and Successful Ageing in Women: A Prospective Cohort Analysis in the Nurses' Health Study" was published in the journal PLoS Medicine at 9am today.
The New Zealand and Australian Science Media Centres sought further comment from experts on the study's findings.
Professor Jennie Connor is Head of Department at the School of Preventative and Social Medicine, Dunedin Schoool of Medicine, University of Otago
"In my opinion this study does not add anything to the many cohort studies that have already been published in this topic or variations of it, including previous analyses of the Nurses Health Study.
All of these studies are unreliable for answering questions about the health effects of drinking because of their design.
"Problems include unreliable self-reporting of past alcohol consumption and underreporting of current alcohol consumption; contamination of the comparison groups and, of most importance, residual uncontrolled confounding. In my opinion, uncontrolled confounding could account for all of the observed effect, or part of it. This means that the differences in health may be due to other differences in lifestyle that are associated with low risk drinking.
"It may be true that women who drink one drink a day are healthier than others, but we do not know if has anything to do with the alcohol, as these women are not the same as others in a variety of other ways.
"This is more of an issue than is acknowledged by the authors when they say: "it is possible that the women who drank moderately share other unknown characteristics that are actually responsible for their increased chance of successful ageing". This is because even the known characteristics are never measured perfectly, and after controlling for these characteristics there will always be some residual influence.
"Because alcohol consumption is so strongly socially patterned and associated with so many other health-related characteristics, I do not believe it is possible to reliably measure the effect on health in a study of this design.
"I feel very strongly that there is no scientific justification for the promotion of alcohol as health-enhancing for any subgroup of the population. The potential for harm is great and the potential for good is unknown. I think that the only ethically defensible approach is to encourage reduction in alcohol consumption in individuals who drink at risky levels and to avoid promoting drinking in those who do not drink or who drink very infrequently and at low levels.
"This does not mean that reliable information about the effects of alcohol should be suppressed, but that unreliable information should not go unchallenged."
The following quotes were collected by the Australian Science Media Centre:
Professor Mike Daube is Professor of Health Policy at Curtin University, WA,where he is Director of the Public Health Advocacy Institute and the McCusker Centre for Action on Alcohol and Youth
"The reported benefits come from drinking at just about the lowest possible levels for regular drinkers - below even the upper levels recommended by the NHMRC.
"This research will clearly need to be examined alongside all the other research on alcohol (and it is also research only on women).
"Nobody should see this as justifying anything beyond very modest levels of drinking. Drinking beyond the NHMRC [National Health and Medical Research Council] upper limits (no more than two standard drinks a day) is still the best way to reduce the risks of harm from alcohol."
Associate Professor Jayne Lucke is Principal Research Fellow at UQ Centre for Clinical Research at The University of Queensland
"This is an important paper showing that regular alcohol consumption by women in middle age is associated with better health at 70. It would be easy to misinterpret this study as evidence that drinking is good for you. Rather, the take home message is that regular small amounts of alcohol in middle age might be good for you. It is not healthy to drink more than currently recommended by the NHMRC [National Health and Medical Research Council].
"Also, drinking a small amount of alcohol may not cause women to age healthily - rather women who regularly drink a small amount may also have a number of other characteristics, such as good health, an active social life and a healthy appetite, that all work together to promote successful ageing.
"It is important to note that women with serious drinking problems were excluded, and only 3% of the women drank at the highest level which was two to three glasses per day. These findings from the US Nurses' Health Study are consistent with findings from the Australian Longitudinal Study on Women's Health (ALSWH). Of almost 12,000 older Australian women aged 70-75 those who did not drink alcohol (or drank rarely) were more likely to die over a six year period compared to those who drank at low levels (Byles et al., 2006).
"Further evidence from the ALSWH shows that the relationship between drinking and disease may differ in young, middle-aged and older women. Young women who did not drink alcohol were less likely to have hypertension and asthma. Middle-aged women who did not drink were more likely to have hypertension, diabetes, heart disease and osteoporosis (and middle-aged women who drank at high-risk levels were more likely to have hypertension than women who drank at low-risk levels).
"Older women who did not drink were more likely to have heart disease and diabetes. The proportion of women who did not drink was higher at older ages: 9% of younger women did not drink compared to 34% of older women (Lucke et al., 2007)."
Dr Lucinda Burns is Senior Lecturer at the National Drug and Alcohol Research Centre at the University of New South Wales
"The findings that women who drink a minimal amount have a modest increase in overall health are not a new finding to the literature but one that continues to cause controversy.
"We know that alcohol has an increasingly detrimental effect on people as they age. This means that they are more likely to have problems such as falls, and the body does not heal as well from these accidents. These types of accidents can occur after drinking one or two drinks.
"As we don't have information on the consumption habits of women who died before 70, it may be the case that alcohol, even what may be regarded as a small amount, may have been a factor in these deaths.
"There are many other ways of promoting healthy ageing other than drinking alcohol, which tends to become an increasingly solitary and lonely pursuit as people get older. For example, increasing the opportunity for meaningful social and cultural activities would seem more appropriate. As the authors note, 'because this is an observational study, it is possible that the women who drank moderately share other unknown characteristics that are actually responsible for their increased chance of successful ageing.'
"Another more appropriate public health message from the findings is that spreading the amount of alcohol consumed over the week is less harmful than drinking the same amount on one occasion."
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