Why the scientific evidence for the health benefits of alcohol is declining

HPeople have been attracted to the idea that alcohol can have health benefits for almost as long. In ancient China, rice wine was widely used for medicinal purposes, while Hippocrates, the ancient Greek “Father of Medicine,” advocated moderate amounts of alcohol for the mind, body, and soul.

Later, temperance advocates who urged working people to stop drinking alcohol in the 19th century encountered resistance from those who believed beer was necessary for good health.

Surprisingly, the theory has since gained a lot of support from modern science. When looking at how the amount you drink relates to your risk of heart disease and death, studies have produced a puzzling but consistent “J-shaped curve” suggesting that drinking a small amount of alcohol is healthier than abstaining completely.

The idea was controversial from the start, however, and as research techniques become more sophisticated, a different picture is emerging – one that regular drinkers may not be happy with.

The first evidence for the beneficial effects of alcohol came from a small study from 1974 of 474 people, which showed that people who drank small amounts had a lower risk of heart attack than both heavy drinkers and teetotalers. In the decades that followed, as scientists were able to interview larger numbers of people, process more data, and take more factors into account, studies repeatedly came to the same conclusion.

As recently as 2011, a meta-analysis published in the BMJ concluded that the lowest risk of coronary heart disease could be achieved with a fairly merry 1-2 drinks a day. And two years ago, the extensive Global Burden of Disease Study suggested that alcohol may benefit people over 40, contradicting their own 2018 finding that any amount of drinking is bad.

These studies, however, are accompanied by a steady chorus of scientists pointing out major methodological flaws. A key problem is that the risk of death among the non-drinking group is often inflated by a significant number of “sick quitters” – people who have stopped drinking for health reasons. Compared with these, it seems clear that sensible types who drink in moderation are likely to live longer.

Another problem is that many studies ask participants to self-report their alcohol consumption, and their answers are likely to be inaccurate and change over time. When researchers take these factors into account, the J-shaped curve often becomes a simple straight line. A paper published earlier this week reanalyzed data from previous studies and found that the lowest risk of death was among those who had never drunk at all.

But according to Tim Stockwell, the lead author of the latest study, this shouldn’t be taken as a definitive answer; rather, it’s an indication of how much work still needs to be done. “Ultimately, we’re not taking our findings literally, we don’t think this is necessarily an accurate picture,” he said. “It’s more like holding up a mirror to how bad the research is.”

A big reason it’s been so hard to tease out the factors involved is that alcohol affects everyone differently, and everyone drinks for different reasons. “It’s tricky with alcohol because it has so many different biological effects,” says Iona Millwood, a researcher at the University of Oxford. “People’s drinking patterns are also shaped by lots of other characteristics that themselves have health implications.”

To avoid these problems, Millwood’s study used a novel approach that separated people who were genetically predisposed to drink more or less alcohol, rather than relying on their self-reported drinking habits. They found that for 61 different outcomes – including many cancers, liver disease, stroke and all-cause mortality – the conclusion was simple: The more you drink, the higher your risk. Other genetic analyses have found similar results.

It’s important to note that the supposed benefits of alcohol only apply to cardiovascular disease and all-cause mortality (although Stockwell suspects that the influence of the former is driving the pattern in the latter). For many other diseases, the evidence is much clearer. For example, the overwhelming consensus on cancer is that any amount of alcohol increases your risk, as supported by a big analysis in which light drinkers were compared with people who had not drunk their entire lives. A significantly lower percentage of oral, colon and breast cancers were found in non-drinkers.

So if the tide of evidence is turning against alcohol’s beneficial effects, why does the idea persist in the public’s conscience? Mark Petticrew, a researcher at the London School of Hygiene & Tropical Medicine, said he believed the drinks industry’s efforts explained a lot. “One reason the public believes in these protective effects is because the industry has funded and promoted research, just as the tobacco industry did.”

As evidence, Petticrew points to a 2021 analysis which looked at 60 different reviews of the impact of alcohol on the risk of cardiovascular disease. It found that 14 of them were either directly funded by the alcohol industry or involved researchers with links to the alcohol industry. All 14 concluded that small amounts of drinking can protect against cardiovascular disease.

Ultimately, however, the scientific basis for this idea seems to be slowly fading, even though people and the beverage companies would like to believe that a daily drink is the key to a long life.