Why the scientific evidence on the health benefits of alcohol is fading | Alcohol

HFor as long as humans have known about drinking, they have been drawn to the idea that alcohol has health benefits. In ancient China, rice wine was used widely for medicinal purposes, while the ancient Greek “father of medicine” Hippocrates recommended alcohol in moderation for the sake of mind, body and soul.

Later, temperance advocates who urged 19th-century workers to give up alcohol faced resistance from people who thought beer was necessary for good health.

Amazingly, this theory has since received a lot of support from modern science: studies of the relationship between alcohol consumption and risk of cardiovascular disease and mortality have found a puzzling yet consistent “J-shaped curve,” which suggests that drinking small amounts of alcohol is healthier than abstaining altogether.

But the idea has been controversial from the start, and now, as research techniques become more sophisticated, a different view is emerging — one that regular drinkers may not want to hear.

The first evidence of the beneficial effects of alcohol came from A small study from 1974 A study of 474 people found that light drinkers had a lower risk of heart attack than heavy drinkers and abstainers. Over the next few decades, as scientists were able to interview more people, analyze more data, and take more factors into account, studies repeatedly came to the same conclusion.

In 2011, A meta-analysis published in the BMJ They concluded that one or two light drinks a day is enough to minimize the risk of coronary heart disease. Broader Global Burden of Disease Study The team suggested alcohol may be beneficial for people over 40, but this contradicts research published in 2018 which found that drinking any amount of alcohol is bad for you.

However, there have been a series of scientists pointing out that these studies have serious flaws in their methodology. One of the core problems is that the mortality risk of non-drinkers is often overestimated due to the large number of “disease quitters” who stopped drinking for health reasons. Compared to these people, it is clear that sensible people who drink in moderation are more likely to live longer.

Another problem is that many studies ask participants to self-report their alcohol intake, answers that can be imprecise and change over time. When researchers take these factors into account, the J-shaped curve tends to become a simple straight line. A paper published earlier this week A reanalysis of data from previous studies found that people who have never drunk alcohol had the lowest risk of death.

But according to Tim Stockwell, lead author of the latest study, this shouldn't be taken as a definitive answer, but rather a sign that there's still a lot of work to be done. “At the end of the day, we're not taking the findings literally and we don't think this is necessarily an accurate picture,” he said. “It's more like a mirror that reflects how bad the research is.”

The main reason why it's so hard to work out the factors involved is that alcohol affects different people differently, and people drink for different reasons. “It's difficult because alcohol has different biological effects,” says Iona Millwood, a researcher at the University of Oxford. “A person's drinking patterns are also determined by many other characteristics that affect their health.”

To avoid these issues, Millwood's research Rather than relying on self-reported drinking habits, the study took a novel approach by distinguishing between people genetically predisposed to drink more alcohol than less.The results showed that for 61 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 Similar results were found.

It's important to note that the effects of alcohol only apply to cardiovascular disease and total mortality (though Stockwell believes that the former effect influences the latter pattern). For many other diseases, the evidence is much clearer. For example, the overwhelming consensus about cancer is that any amount of alcohol intake increases risk, and this is supported by the following studies: Large-scale analytics When comparing light drinkers with lifetime abstainers, non-drinkers were found to have significantly lower rates of oral, intestinal and breast cancer.

So why has the idea persisted in the public conscience when the tide of evidence has turned against the beneficial effects of alcohol? Mark Petticrew, a researcher at the London School of Hygiene and Tropical Medicine, thinks the drinks industry's efforts explain a lot: “One of the reasons the public believe in these preventative effects is because the industry has funded and promoted the research, just like the tobacco industry.”

As evidence, Petticrew 2021 Analysis They looked at 60 different reviews on the effect of alcohol on cardiovascular disease risk and found that 14 of them were directly funded by the alcohol industry or involved researchers with ties to the alcohol industry. All 14 concluded that drinking small amounts of alcohol can protect against cardiovascular disease.

After all, as much as people and beverage companies may want to believe that having a daily alcoholic drink is the secret to living a long life, the scientific support for that idea appears to be gradually fading.