How much and how often should we drink?
Authors: Annie Britton
Journal: BMJ (2006)

People choose to drink alcohol for all sorts of reasons, from toasting the happy couple to drowning sorrows and numbing pain. Few people choose to drink primarily to reduce their risk of coronary heart disease. However, the paper by Tolstrop and colleagues on p 1244 will be welcomed by many.1 The authors studied more than 50 000 Danish men and women and report that to gain maximum cardioprotective benefit from alcohol, it doesn't matter how much men drink as long as they drink every day. I can hear the corks popping already, but before pouring the next glass and at the risk of being a wet—or should that be dry—blanket, it is worth bearing several caveats in mind.

Firstly, this finding applied only to men. For women it was the amount of alcohol consumed, regardless of frequency, that was the primary determinant in the relation between alcohol and heart disease. This raises interesting possibilities about gender specific alcohol metabolism. The Danish participants were middle aged and therefore presumably at increased risk of heart disease. The epidemiological evidence on how drinking is related to the risk of heart disease over the life course is scarce and we do not yet know whether cardioprotective benefits accrue over a lifetime or whether, purely from a health perspective, we should defer drinking alcohol until older age, when heart disease is manifest.

The low response rate of 35% (160 725 Danish men and women were invited to participate in the study, and 27 178 men and 29 875 women did participate) means that there may be extremes of drinking which were not captured and that there is a limit to the amount that can be consumed daily. And, as the authors note, residual confounding—the bane of observational epidemiology—may partly explain the findings.

Before advising patients about their frequency of drinking, of course, we must consider the bigger picture in terms of health and social consequences of alcohol consumption. For some alcohol related conditions, it is clear that the pattern of consumption will be of paramount importance. Alcohol related injuries or ethanol toxicity, for example, suggest a degree of inebriation. It is not so clear that chronic diseases such as alcohol related cancers or cirrhosis will be affected by frequency of consumption, as opposed to volume. The limited earlier epidemiological evidence on drinking pattern and cardiovascular disease suggested that pattern of consumption is crucial to whether alcohol confers a positive or negative effect. This hypothesis is supported by the evidence that the physiological effects of regular moderate drinking and binge drinking are markedly different.2

Ideally practitioners should find out not only how much patients consume, but in what context and why. A recent report by the UK Mental Health Foundation suggests that among daily drinkers (estimated to be nearly 1 in 10 people in the United Kingdom—about 5 million people) alleviation of anxiety and depression is cited as a common reason for drinking.3 Advising patients on volume and frequency of alcohol would depend on their age and susceptibility to heart disease and, in light of Tolstrup and colleagues' research, perhaps on their sex.

Alcohol is here to stay in our lives. It is not like cigarette smoking, which is being increasingly outlawed. Unlike tobacco, the healthiest amount of alcohol for some people may not be zero. So people need advice and legislation on keeping consumption safe. In the UK, levels of consumption have risen by more than 50% in the past 30 years, accompanied by a rise in alcohol related deaths, particularly from liver cirrhosis.4

As a population we are drinking well above the optimum level for health. The evidence suggests that raising the price and limiting availability of alcohol will reduce the average consumption and the prevalence of harmful consumption.4 It will be interesting to see the consequences of the recent relaxation of licensing hours and increased availability of alcohol in England.5

Clearly, it would be unwise for doctors to advise non-drinkers to start drinking in an attempt to prevent cardiac disease when there are other strategies, supported by data from clinical trials, that have fewer harmful side effects. However, the general population makes lifestyle decisions on the basis of many factors, not least views expressed in the popular press. Research such as that conducted by Tolstrop and colleagues is widely disseminated in the media and may be used by some people as a justification for their potentially harmful drinking behaviour. Sadly, it is difficult to control the media's sensationalist interpretations of epidemiological findings.