The emerging medical consensus around alcohol is likely to come as a downer for drinkers. Here’s everything you need to know:

Is moderate drinking harmless?

For decades, doctors advised that consuming a daily alcoholic beverage or two is fine for one’s health, or perhaps even beneficial. A growing body of research, however, indicates that toasting “To your health!” is an oxymoron. Studies have found that even modest drinking can have negative consequences, including raising the risk of cancer and heart attacks. “Risk starts to go up well below levels where people would think, ‘Oh, that person has an alcohol problem,'” said Dr. Tim Naimi, director of the University of Victoria’s Canadian Institute for Substance Use Research. This emerging consensus comes amid a rise in alcohol consumption during the pandemic, as Americans sought an escape from despair and boredom. Cleveland Clinic cardiologist Stanley Hazen said that, in light of new research, he will advise his patients that even the current U.S. guidelines for moderation — two drinks a night for men and one a night for women — might be risky. “I am going to be recommending cutting back on alcohol,” Hazen said.

How high is the risk of cancer?

Alcohol contributes to more than 75,000 new cancer cases per year in the U.S. and nearly 19,000 annual cancer deaths, according to the American Cancer Society. When humans consume alcohol, they metabolize it into acetaldehyde. This toxic chemical can damage DNA, enabling the out-of-control cell growth that creates cancerous tumors. Alcohol is known to be a direct cause of seven types of cancer: oral cavity, pharynx (throat), larynx (voice box), liver, breast, and colorectal. According to the National Cancer Institute, moderate drinkers are 1.8 times more at risk of oral cavity and pharynx cancers, while heavy drinkers are five times more at risk. For liver cancer, increased risk comes only from excessive drinking. Studies indicate that for postmenopausal women, just one drink a day raises their risk of breast cancer by up to 9 percent compared with nondrinkers.

What are the other dangers?

Alcohol is the third-leading cause of preventable death in the U.S., and alcoholic liver disease kills 22,000 Americans every year. Risk of liver disease is greatest among heavy drinkers, but one report found that drinking just two alcoholic beverages a day for five years can damage the liver. One drink per day, Hazen said, increases the risk of heart attack and stroke by 10 to 20 percent. Research suggests that alcohol may accelerate genetic aging and exacerbate dementia, and a study published last year found that drinking just a pint of beer or glass of wine a day can kill neurons and shrink the brain.

Doesn’t wine help your heart?

For years, researchers believed that moderate amounts of red wine can be healthy, raising the “good” cholesterol HDL and protecting the heart. This was based on the presence of antioxidants found in grapes, such as resveratrol, which is thought to protect blood vessels and slow aging. But a 2016 study found that a person would have to drink at least 500 liters of red wine every day to consume enough resveratrol to get significant benefits. Some specialists maintain that alcohol can improve glucose control, but even low levels of drinking can also increase the risk of high blood pressure, stroke, and an abnormal heart rhythm. “Contrary to popular opinion,” the World Heart Federation declared last year, “alcohol is not good for the heart.”

Why were experts so wrong?

Alcohol studies are largely observational or based on self-reports; it would be unethical to instruct a random group of study volunteers to drink in excess. That means researchers can’t control other variables that might influence health. Older studies that found that moderate drinking is beneficial relied on comparisons of light drinkers with people who don’t drink at all. Researchers have since realized that people might abstain from drinking altogether because of underlying ailments, so if light drinkers appear healthier, it’s not the alcohol creating the difference. A study published last year based on medical data from nearly 400,000 people in the UK Biobank appeared to confirm this, finding that light drinkers tend to have healthier habits — such as exercising and eating well — compared with people who don’t drink at all.

How much do Americans drink?

About 60 percent of Americans told Gallup in 2021 that they drink, and estimated they had on average 3.6 drinks per week. But nearly half of Americans reported bingeing in the past months — defined as consuming more than four drinks in a sitting for men and more than three for women. In light of new research, some researchers recommend completely abstaining, but most doctors and experts suggest cutting back instead. “I’m not going to advocate that people completely stop drinking,” said George Koob, director of the National Institute on Alcohol Abuse and Alcoholism. “We did Prohibition. It didn’t work.”

Why people react differently

Alcohol has a greater impact on women’s health than men’s. Women tend to be lighter than men and have lower lean body mass, which determines alcohol’s concentration in the brain. Women also produce less of the alcohol-metabolizing enzyme known as alcohol dehydrogenase. Race can also be a factor: Between 15 and 25 percent of white people carry a genetic risk for alcohol abuse, compared with less than 5 percent of Black Americans, according to Dr. David Streem, medical director of the Cleveland Clinic’s Alcohol and Drug Recovery Center. People of East Asian descent often carry two genetic variants that affect how alcohol is metabolized. One variant causes alcohol to break down faster into the toxin acetaldehyde. The other variant slows metabolism of that compound, causing it to linger in the body longer. People with this genetic variant tend to look flushed or feel sick after just a few sips of alcohol. For most people, harm from drinking “really accelerates once you’re over a couple of drinks a day,” Dr. Naimi said. “So people who are drinking five or six drinks a day, if they can cut back to three or four, they’re going to do themselves a lot of good.” 

This article was first published in the latest issue of The Week magazine. If you want to read more like it, you can try six risk-free issues of the magazine here.