How much alcohol is safe to drink? Here’s what experts say

The U.S. surgeon general’s advisory Friday calling for health warning labels on alcohol to include risks of certain cancers raises questions about whether there is a safe amount of alcohol consumption and how much does alcohol raise the risk of certain cancers.

We asked Vivek H. Murthy and other physicians these and other questions.

Most people don’t know that alcohol consumption increases alcohol-related cancer risk, Murthy said. Alcohol is responsible for 100,000 cases of cancer and 20,000 deaths from cancer in the United States each year.

“It’s important for people to understand the risks so that they can make the best decisions for themselves and for their families. So, that’s why I’m issuing this advisory,” Murthy said.

Murthy also said that current guidelines on alcohol consumption - one drink a day for women and two drinks a day for men - should be revised because there is a significant increase in cancer and people’s risk of cancer within those limits.

How much alcohol is safe to drink?

There is no “safe amount of alcohol consumption,” researchers from the World Health Organization advise. Drinking as few as one standard drink per day raises the risk of certain cancers.

But Murthy cautioned that while “there may not be a zero-risk level, there are lower risks and there are higher risks.”

Cancer risk is “significantly lower” for someone who drinks one or two drinks a week than somebody who drinks one or two drinks a day, he said. “Less is better when it comes to reducing,” cancer risk, Murthy said.

This is especially important for those who are at an increased risk of cancer because of family history, genetic predispositions or environmental exposures, and those worried about developing cancer, he said.

How much does alcohol increase cancer risk?

It’s difficult to explain a person’s risk of developing cancer because of alcohol consumption, said Otis Brawley, a professor of oncology and epidemiology at the Bloomberg School of Public Health at Johns Hopkins University.

The associated risk is different for each type of cancer. And someone’s risk goes up if they’ve been drinking regularly for a longer period of time, he said. Binge drinking “is especially bad,” Brawley said.

But other risk factors, such as obesity or smoking, also increase a person’s risk of developing cancer, he said.

Tobacco is the No. 1 carcinogen driving cancer risk, but as tobacco use falls, the relative risk of alcohol-related cancers will increase, said William Dahut, chief scientific officer at the American Cancer Society. “I do think it’s important folks are at least aware of this real - and really good - scientific evidence, of this link between alcohol and cancer,” he said.

Murthy said it is challenging to “translate population data or population-based recommendations to an individual.”

Seven types of cancer are causally linked to alcohol consumption, Murthy said: breast, colorectal, mouth, throat, voice box, esophageal and liver cancer.

The overall risk of breast cancer, for instance, increases 4 percent from drinking fewer than one drink per week to two drinks per day; “out of 100 women, four more will develop breast cancer due to consuming two drinks a day,” he said.

“Over the population, that’s a lot of women who would develop breast cancer. At the population level, that kind of change, even though it might seem small by the numbers, actually really does matter,” Murthy said.

The absolute risk of developing alcohol-related cancer in their lifetime for men is approximately 10 percent, or 10 of every 100 men, and for women is approximately 16.5 percent, or about 17 of every 100 women, for those who consume less than one drink of alcohol a week, according to data referenced in the surgeon general’s advisory. The risk increases to around 11 of every 100 men, and 19 of every 100 women, for those who drink alcohol every day. And the absolute risk rises to 13 of 100 men, and about 22 out of 100 women, for those who consume two drinks a day.

But people shouldn’t panic, Brawley said.

If you’re a light drinker, the surgeon general’s advisory doesn’t mean you are definitely going to develop cancer from drinking, Brawley said. The risk is slightly higher for “light, social drinkers” and that risk increases for binge drinkers.

People who have had cancer before or who have a family history of certain alcohol-related cancers “need to be really thoughtful” about their alcohol use, Dahut said.

“If you’ve had heavy alcohol use in the past, or you’re concerned, you should probably talk to your physician,” he said. “Your alcohol use should be part of how you think about your own individual cancer screening.”

Are there benefits of alcohol consumption?

We used to think red wine conferred some health benefits, protecting people against cardiovascular disease, said Timothy R. Rebbeck, a professor of cancer prevention at the Harvard T.H. Chan School of Public Health. But as the research has evolved, the evidence supporting the health claim “has become a little weaker” and the evidence for the risk of cancer has “become stronger.”