December 3, 2020

Should We Be Drinking Less?

Can a daily drink or two lead to better health?

For many years, the federal government’s influential dietary guidelines implied as much, saying there was evidence that moderate drinking could lower the risk of heart disease and reduce mortality.

But now a committee of scientists that is helping to update the latest edition of the Dietary Guidelines for Americans is taking a harder stance on alcohol. The committee said in a recent conference call that it plans to recommend that men and women who drink limit themselves to a single serving of wine, beer or liquor per day. Do not drink because you think it will make you healthier, the committee says: It won’t. And it maintains that drinking less is generally better for health than drinking more.

That message is a departure from previous guidelines, which since 1980 have defined “moderate” drinking as up to two drinks a day for men and one for women. Government agencies have also long defined a standard drink as 12 ounces of regular beer, five ounces of wine, or one and a half ounces of distilled spirits (40 percent alcohol), amounts often exceeded in Americans’ typical “drink.”

Between 1990 and 2010, many editions of the guidelines, which are updated every five years, discouraged heavy drinking and warned pregnant women and people with certain medical conditions not to drink. But they also noted that moderate drinking was linked to fewer heart attacks and lower mortality. The 2010 guidelines mentioned that moderate drinking may even “help to keep cognitive function intact with age.”

The new recommendation would be a victory for experts who have long questioned the health halo around moderate drinking. They say that studies showing it can protect health are deeply flawed, and that any potential cardiovascular benefits would be outweighed by the fact that alcohol is a leading preventable cause of cancer. According to the National Cancer Institute, even one drink a day increases the risk of breast, esophageal and oral cancer.

“This is significant because the committee has finally gotten away from this idea that a small amount of alcohol is good for you,” said Thomas Gremillion, the director of food policy at the Consumer Federation of America, a public interest group that has pushed for cancer warnings on alcohol. “They’re really taking a stand and saying drinking less is always better. That’s the right message and I think they deserve credit for making that change.”

The new advice is not yet final. The advisory panel is expected to include it in a report that it will release publicly in mid-July and submit to the Department of Agriculture and the Department of Health and Human Services. Those two agencies are scheduled to publish the official dietary guidelines later this year.

If accepted, the new recommendation would make the United States the latest country to issue stricter guidelines on alcohol consumption. In recent years, Britain, Australia, France and other countries have issued new guidelines lowering their recommended limits on daily and weekly alcohol intake. Health authorities in those countries have said that recent evidence suggests consuming less alcohol is safer and that even one drink a day increases cancer risk.

The scientific debate over moderate drinking dates at least back to the 1970s, when researchers in California noticed that teetotalers seemed to have more heart attacks than people who drank moderately. In the decades that followed, many observational studies looking at large populations documented what is known as a J-shaped curve between alcohol and mortality from all causes, especially heart disease: Mortality rates dipped for moderate drinkers compared to nondrinkers and then climbed higher among people whose intake exceeded one or two drinks daily.

But observational studies can show only correlations, not causation. And they have other limitations. One major confounding factor is that socioeconomic status is a strong predictor of health and life span — and it tracks closely with drinking levels. Studies show that compared to heavy drinkers and abstainers, people who drink moderately tend to be wealthier and have higher levels of education. They tend to have better health care, exercise more, eat healthier diets, and have less obesity.

One study that compared nondrinkers to moderate drinkers — defined as having two drinks daily for men and one for women — found that 27 out of 30 well established risk factors for heart disease were “significantly more prevalent” among nondrinkers. Rather than causing better health, in other words, moderate drinking may be a marker for higher socioeconomic status and other lifestyle factors that promote a longer life.

Another problem with observational studies is selection bias. In some large studies, people categorized as “nondrinkers” may actually be former heavy drinkers, or they may have health issues that cause them not to imbibe. Studies have found that nondrinkers have higher rates of physical disabilities, psychiatric problems and pre-existing illnesses. When rigorous studies take these factors into account, they find that the protective effect of moderate drinking disappears.

“The appearance of protection vanishes like the mist on an autumn day as the sun comes up,” said Timothy Stockwell, an alcohol researcher and director of the Canadian Institute for Substance Use Research at the University of Victoria. “All of these thousands of studies, when you do a forensic examination of them, most of them have these horrendous flaws and are open to these systematic biases.”

One way to get around these limitations is through genetic studies. Some people carry a genetic variant that disrupts their ability to metabolize alcohol, causing them to develop skin flushing, irritation and other unpleasant symptoms when they drink alcohol. As a result, they tend to abstain or drink very little. If alcohol was good for heart health, these people should in theory have more heart disease compared to others. Instead, as one large analysis published in BMJ in 2014 found, they have “a more favorable cardiovascular profile and a reduced risk of coronary heart disease than those without the genetic variant.”

The study concluded: “This suggests that reduction of alcohol consumption, even for light to moderate drinkers, is beneficial for cardiovascular health.”

Not everyone agrees that the health benefits of moderate drinking are illusory. Alcohol has blood-thinning properties, and red wine in particular contains polyphenols that have beneficial effects on the microbiome, said Dr. Erik Skovenborg, a family doctor and member of the International Alcohol Forum, an international group of scientists who study alcohol and health. Alcohol also raises HDL cholesterol, often referred to as the “good” kind, though recent studies have cast doubt on it being cardioprotective.

Dr. Skovenborg said the observational data makes it clear that moderate drinking is more than a marker for a healthy lifestyle.

“In these studies you have many participants that have all the healthy lifestyle factors,” he said, “and if you add moderate alcohol consumption on top of that, it increases the benefits regarding longer life and fewer health problems.”

Dr. Skovenborg said his general advice to patients who drink is to follow the Mediterranean tradition: Have a little wine with your meals, drink slowly, enjoy it, and don’t drink to get drunk. Exercise regularly, avoid smoking, eat nutritious foods, and maintain a normal weight. “It’s a pattern of things you should be doing, not just one thing,” he added.

Showing definitively that moderate drinking protects heart health requires doing a lengthy clinical trial, one that randomly assigns some people to have a drink daily and others to abstain. In 2014, the National Institutes of Health launched a clinical trial designed to do just that. But it was shut down in 2018 after a New York Times investigation revealed that N.I.H. officials had lobbied beer and liquor companies for funding and suggested that the results of the trial would support moderate drinking. As it turns out, experts have long raised concerns about industry influence on alcohol studies.

Members of the advisory committee declined to comment on their recommendations until their report is released. Dr. Stockwell said he agreed with the one-drink-a-day recommendation but he would word it slightly differently. “I’d probably say seven drinks a week for men and women and no more than two drinks on one day,” he said. “I would have a little flexibility.”