Drinking alcohol is bad for you, but it is often a social activity.
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Rigorous research suggests that drinking even small amounts of alcohol can shorten your lifespan, and that only people with serious health problems would benefit from moderate drinking. That’s the conclusion of a review of 107 studies that looked at how drinking alcohol at specific ages affects the risk of dying from all causes.
“People need to be skeptical of the claims that the industry has been peddling for years,” says Tim Stockwell of the University of Victoria in Canada. “They clearly have a huge interest in promoting their products as not causing cancer but as extending life.”
Stockwell says people should be told that while the risks of moderate drinking are small, it’s not beneficial. “It may not be as dangerous as a lot of other things, but it’s important that consumers are aware,” he says. “I also think it’s important that manufacturers inform consumers of the risks through warning labels.”
The best way to assess the effects of alcohol would be to randomly select people who drink and who don’t drink as children, and then monitor their health and drinking for the rest of their lives. Because such studies are not possible, researchers instead have to ask people about their drinking habits and follow them over a much shorter period of time.
By the 2000s, a number of such studies had been done, suggesting that the relationship between alcohol consumption and risk of death at a given age follows a J-shaped curve: drinking a little alcohol slightly reduces your risk of dying from any cause compared with a non-drinker, but as you drink more alcohol, your risk increases sharply.
Stockwell says he was convinced the science was sound at the time, but since then he and other researchers have shown that such studies are deeply flawed.
The main problem is that they often don’t compare people who have never drunk alcohol to people who have. Many studies instead compare people who no longer drink to people who still drink. People who stop drinking, especially later in life, often have health problems, so moderate drinkers seem healthy in comparison, Stockwell says.
Although some studies claim to compare current drinkers to “never drinkers,” the definition of the latter group often actually includes occasional drinkers, Stockwell says. For example, one study defined people who consumed up to 11 drinks a year as lifetime abstainers.
“In our opinion, the majority of research has not addressed this potential source of bias,” Stockwell says, “To be clear, people have tried to address this, but we don’t think they’ve done so adequately.”
In fact, his team found that of 107 studies they reviewed, only six adequately addressed these sources of bias, and none of those six found any risk reduction with moderate drinking.
“The (high-quality) studies suggest a linear relationship,” Stockwell said. “The more you drink, the higher your risk of heart disease. Our study looked at all-cause mortality, and heart disease is clearly the main issue.”
Duane Mellor, from the British Dietetic Association, said the review made it very clear that lower quality studies were more likely to suggest a beneficial effect.
But he points out that this doesn’t take into account the social aspects of moderate drinking. “While it’s healthier to socialize without drinking alcohol, the benefits of spending time with other people are likely to outweigh the risks of consuming one or two units of alcohol,” he says. “Perhaps the challenge is to limit alcohol intake in this way.”
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