Your Top Questions About Moderate Drinking and Health, Answered

Is drinking a glass of wine every night good or bad for your health? Somewhere in between?

If you’re unsure, you’re probably not alone. For decades, research on the health effects of moderate drinking has been contradictory, with some studies saying that a little alcohol can be good for you while others suggest that it’s harmful.

The conflict has been on display in recent months, with the release of assessments that will be used to shape the U.S. Dietary Guidelines this year. Researchers from two federal organizations reviewed the science on moderate drinking—and reached some different conclusions about how it affects health.

The first report, released by the National Academies of Sciences, Engineering, and Medicine in December, determined that moderate drinking is linked to fewer heart attack and stroke deaths. It also found a small but significant risk of breast cancer—but said there wasn’t enough evidence to connect moderate drinking with other cancers.

The Interagency Coordinating Committee for the Prevention of Underage Drinking, which released its analysis weeks later, came to a different conclusion: It found that a daily drink raises the risk of developing esophageal and oral cancers, as well as liver cirrhosis. It also said that drinking is linked to a higher chance of death from seven types of cancer, including breast, colorectal, and liver.

Though researchers found that people who had no more than one drink a day had a lower risk for stroke (an apparent protection they said disappears if you drink heavily, even infrequently), they didn’t conclude that moderate drinking lowers the chances of ischemic heart disease (also called coronary artery disease), a risk factor for heart attack.

Given the disparate findings, it’s understandable to be confused about the potential toll that moderate drinking can take on your body. That’s why we asked experts to unpack what effect, if any, your happy hour habit might have on your disease risk.

The most frequently cited definition of moderate drinking comes from the Centers for Disease Control and Prevention, which defines it as consuming one drink a day or fewer for biological women and two or fewer for men. The agency considers a single drink to be a 12-ounce beer, a 6-ounce glass of wine, 8 ounces of malt liquor, or 1.5 ounces of 80-proof liquor, the equivalent of a shot. The weekly limit is seven drinks for women and 14 for men.

The problem is that what constitutes a drink is “in the eye of the beholder,” Steve Nissen, MD, the chief academic officer of the Heart, Vascular and Thoracic Institute at Cleveland Clinic, told Health. “It’s all about the amount of alcohol you’re having.”

Some bars have particularly stiff drinks, and some craft beer has an alcohol content as high as liquor. Nissen said these things can make it difficult to pin down what constitutes a single drink.

The conflicting findings stem from the particular design of alcohol studies, experts said.

All of the studies about alcohol’s effect on health are observational—meaning that researchers have participants report their behavior (in this case, drinking amount or frequency) and discern health outcomes through self-reporting or medical records.

While these studies can give researchers an idea about how different habits may affect specific parts of health, they can only establish correlation—not causation.

For a concrete cause and effect to be established, the research must be the gold standard randomized clinical trial. That type of design would eliminate other potential factors—for example, participants having a healthier diet or exercising frequently—that could actually account for moderate drinking’s link with certain health outcomes.

“Without that, you’re going to have all these contradictory studies coming out,” Nissen said.

Scientists know that alcohol is carcinogenic, or cancer-causing. In the body, alcohol turns into a carcinogen called acetaldehyde. If acetaldehyde builds up in the body, it damages DNA and prevents cells from reproducing or repairing themselves. That leads to oxidative stress.

“If that is a cell that needs to divide and replace itself, like the lining of the gastrointestinal tract, which divides and replaces itself every three days, it needs to do that in a regular and perfect way,” Elizabeth Kovacs, PhD, a professor of surgery at the University of Colorado Anschutz Medical Campus who leads the University of Colorado School of Medicine’s Alcohol Research Group, told Health. “One of the most direct effects alcohol can have is it can cause damage to DNA.”

But what’s less clear is the effect that drinking in moderation, specifically, has on cancer risk. Research on the topic is sparse to begin with, and studies that do exist are observational, as mentioned, so they don’t provide the highest-quality data.

When taken together, the new reports implicate moderate drinking with a higher risk of breast, esophageal, and oral cancer, but an advisory from the Surgeon General outlines even more dire outcomes.

That advisory suggests that having a daily drink may raise the risk of a woman developing an “alcohol-related cancer”—breast, colorectal, voice box, liver, mouth, and throat—by about 2.5%, compared to drinking less frequently. For a man, it ups the chances by roughly 1.4%.

There may be a more significant difference between people who drink moderately and those who don’t drink at all. In a study published in 2013, researchers compared the cancer risk of people who consume no more than one daily drink to those who drink nothing. They found that compared to people who abstained, daily drinkers had a 5%, 30%, and 17% higher risk of breast cancer, oral cavity and pharynx cancers, and esophageal cancer, respectively.

“Doing it once in a while is very different from drinking regularly,” Kovacs said.

While some studies suggest that moderate drinking can benefit the heart, others haven’t found such a link. Much of the research has focused on red wine, which contains antioxidants called polyphenols. Researchers have found an association between a polyphenol in red wine called resveratrol and a reduced risk of heart disease, primarily due to its anti-inflammatory effects.

But again, because the research is observational, it’s difficult to know how moderate drinking truly affects heart health.

Nissen said he’s “willing to accept” that moderate drinking has the “potential for a small benefit for heart health” but that drinking’s potential health risks outweigh any possible good.

“If you’re drinking, don’t think it’s because of a health benefit,” said Daniel Schatz, MD, the medical director of substance use disorder services at NYC Health + Hospitals.

It’s worth noting that for people who take certain heart-related medications, including warfarin, cholesterol, and blood pressure drugs, drinking alcohol can reduce the effectiveness or increase side effects. Alcohol can also cause dangerously high blood pressure for some people taking antidepressants.

Research has found that moderate drinking is associated with fatty liver disease, a condition in which excessive fat accumulates in the liver. Over time, it could lead to liver cancer or cirrhosis.

Your daily drinking habit can also lead to other patterns that aren’t great for health, said Schatz. “There are a lot of behavior changes that happen when you’re drinking,” he told Health. “You aren’t exercising as much and aren’t eating well.” 

Alcohol use disorder, which has strongly been linked to poor health, can also start from a moderate drinking habit, he added.

Experts said it’s possible to undo the negative effects of moderate alcohol consumption, but this would depend on the damage and the person’s unique characteristics and habits.

One condition that Schatz noted can be reversed is fatty liver disease—as long as you’re also exercising and eating well in addition to laying off the alcohol. “Your body is amazing,” he said.

But experts suggest warding off potential health conditions by not drinking too much to begin with. While having the occasional drink probably isn’t detrimental to your overall health, Schatz recommends not making a habit out of it. “If you like the taste or it relaxes you—OK,” he said. “Just know that even moderate amounts of alcohol can be harmful.”