It is becoming clear that any amount of alcohol is harmful, so why do so many studies claim that moderate drinking could help you live longer?
Drinking even small amounts of alcohol reduces your life expectancy, rigorous studies show. Only those with serious flaws suggest that moderate drinking is beneficial. That’s the conclusion of a review of 107 studies looking at how drinking alcohol affects people’s risk of dying from any cause at a particular age.
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| Drinking alcohol isn’t good for you, but it is often a sociable activity Violeta Stoimenova/Getty Images |
“People need to be sceptical of the claims that the industry has fuelled over the years,” says Tim Stockwell at the University of Victoria in Canada. “They obviously have a great stake in promoting their product as something that’s going to make you live longer as opposed to one that will give you cancer.”
While the risks of moderate drinking are small, people should be told that it isn’t beneficial, says Stockwell. “It’s maybe not as risky as lots of other things you do, but it’s important that consumers are aware,” he says. “I think it’s also important that the producers are made to inform consumers of the risks through warning labels.”
The best way to assess the effects of alcohol would be to randomly assign people to drink it or not in childhood and then monitor their health and drinking over the rest of their lives. Since such studies cannot be done, researchers instead have to ask people about their drinking habits and follow them over much shorter periods of time.
By the 2000s, numerous studies of this kind had suggested that the relationship between drinking and the risk of dying at a particular age made a J-shaped curve. That is, if people drank a little then their risk of dying of any cause went down a bit compared with non-drinkers, but drinking more led to a sharp increase in the risk.
Stockwell says he was convinced the science was settled at the time. But since then, he and others have shown that there are major flaws in such studies.
The main problem is that they often don’t compare people who have never drunk alcohol with those who have. Many studies instead compare people who no longer drink with those that still do. People who give up drinking, especially later in life, often do so because they have health problems, says Stockwell, so moderate drinkers appear healthier in comparison.
Some studies claim to compare current drinkers with “never drinkers”, but their definitions of the latter group often actually include occasional drinkers, says Stockwell. For instance, one study defined people as lifetime abstainers even if they drank on up to 11 occasions every year.
“The great majority of studies do not, in our opinion, deal with this potential source of bias,” says Stockwell. “To be clear, people have attempted to deal with this. We don’t think that they’ve dealt with it appropriately.”
In fact, his team found that just six of the 107 studies they reviewed adequately dealt with these sources of bias – and none of these six found any reduction in risk with moderate drinking.
“The [high-quality] studies suggest a linear relationship,” says Stockwell. “The more you drink, the higher your risk of heart disease, which is obviously the main issue even though our studies look at all-cause mortality.”
The review shows very clearly that poorer quality studies are more likely to suggest a beneficial effect, says Duane Mellor at the British Dietetic Association.
But he points out that it doesn’t consider the social aspects of moderate drinking. “It is healthier to socialise without the need for alcohol, but the benefits of spending time with others is still likely to be greater than the risk from the consumption of one to two units of alcohol,” he says. “The challenge being perhaps limiting alcohol intake in this way.”
Journal reference:
Journal of Studies on Alcohol and Drugs DOI: 0.15288/jsad.23-00283
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