The latest thinking on drinking

photo of a group of three women smiling while toasting with glasses of red wine

If your Dry January quickly turned damp and later splashed into nightly cocktails on the patio, you probably weren't enthused by a recent analysis suggesting women's risks of dying early rise markedly when we drink an average of just under two alcoholic beverages a day.

But perhaps another recent study made you nod with satisfaction — one suggesting alcohol lowers the risk of heart attack and stroke by improving stress signaling in the brain.

What to believe? Not what the headlines blare, since most scientific evidence surrounding alcohol's health effects is decidedly weak, Harvard experts say. Tracking it — and gleaning useful insights into how we should shape our drinking habits — is not unlike watching an annoying ping-pong match. One day, drinking is touted as beneficial; the next, it's terrible. Back and forth, back and forth, until you want to ignore it all.

"Everything that comes out seems to capture our attention, but the evidence has always been prone to being misunderstood or misinterpreted," says Dr. Kenneth Mukamal, an internist at Harvard-affiliated Beth Israel Deaconess Medical Center who studies how alcohol and other lifestyle factors affect health. "With this yo-yo effect, every new study seems important, because we don't have strong evidence. It makes people's heads explode."

Research holes

For context, here's how drinking levels are categorized. A standard drink equals 1.5 ounces of distilled spirits, a 12-ounce beer, or a 5-ounce glass of wine. The CDC defines moderate drinking as one standard drink or less per day for women and two drinks or less for men. Heavy drinking is eight or more drinks a week for women and 15 or more per week for men.

But while those amounts seem clear, the related research is anything but. Part of the problem is that alcohol's health effects have never been studied in what's considered a scientifically rigorous way.

"There's never been a large-scale randomized controlled trial that's tested how reducing or increasing alcohol intake affects health," says Dr. JoAnn Manson, chief of the Division of Preventive Medicine at Harvard-affiliated Brigham and Women's Hospital. This gold-standard study design would pit one scenario directly against the other, rather than rely on observations that could be influenced by extraneous factors.

Another conundrum is that drinking and other lifestyle habits that influence health, like exercise, sleep, and social connectedness, can't easily be teased apart in study findings. The 2023 research review suggesting women's risks of dying early rise significantly from consuming just under two alcoholic drinks a day was intended to correct some of those design flaws. That study's authors said earlier analyses didn't point out that people considered light or moderate drinkers tend to have other healthy habits that improve their overall health — making it appear that alcohol contributes to good health outcomes. Conversely, "nondrinkers" in study comparison groups have often included people who once drank and quit because of addiction or other health problems. This factor skewed study findings to suggest drinking moderately was healthier than not drinking at all.

"We now understand those findings were likely spurious," Dr. Manson says.

Breast cancer caveat

One of the more robust findings involving alcohol's effects on health pertains specifically to women: drinking has been convincingly linked to developing breast cancer, as well as other cancers.

A 2021 report from the International Agency for Research on Cancer estimated that alcohol accounts for about 4% of newly diagnosed cancers globally — most commonly those of the breast, esophagus, and liver. And breast cancers accounted for almost half of the more than 23,000 new cancer diagnoses in Europe traceable to light-to-moderate drinking in 2017, according to a January 2023 study in The Lancet Public Health.

While the number of women who develop breast cancer every year due solely to alcohol is small, it's something we should consider before we imbibe. "The alcohol–breast cancer link is among the strongest evidence we have," Dr. Mukamal says. "Women who drink alcohol have higher levels of sex hormones like estrogen. If you're prone to breast cancer, this feeds it in a way it wouldn't if you weren't drinking."

Any woman concerned about her breast cancer risk — or whose mother, sister, or daughter has had the disease — should consider reducing or eliminating alcohol, says Dr. Manson, who is also a professor of medicine and women's health at Harvard Medical School. "It would be a strategy to mitigate risk," she says.

Horsche

How do you know if you need to quit drinking?

If you reach for a drink just to feel normal, alarm bells should be ringing. That's a clear sign alcohol is more than just an enjoyable pursuit — it's a problem, says Dr. Robert Doyle, a psychiatrist at Harvard-affiliated Massachusetts General Hospital.

But many warning signs that suggest you stop drinking are more subtle, and it's common to slide into alcohol misuse by gradually drinking more and more without realizing it's excessive, Dr. Doyle says.

"A person who develops alcohol use disorder tends to be someone who, early on, is able to handle their alcohol," he says. "They don't seem to get drunk so easily, but then they start to drink more and their body becomes accustomed to it. It tends to sneak up on them."

Watch for these other signs that suggest you are drinking too much:

You crave alcohol to feel relaxed. People with alcohol use disorder often say that's why they drink, but they're usually imbibing to avoid the physical symptoms of withdrawal.

You drink alone. "You're wanting to just drink instead of socialize," Dr. Doyle says.

Your job or relationships have suffered. "You might miss work because you pass out and oversleep," he says, "or you're not meeting your obligations because of your drinking."

You hide your drinking. That might mean drinking in secret or concealing bottles around your home.

You drive after drinking. "The wake-up call is getting pulled over for a DUI or the threat of it," he says.

Your family tells you you've got a problem. "Pay attention to what they say, or ask your family, 'Do you think I overdo it?' Tell them you won't be mad at them for being honest," Dr. Doyle suggests. "Family members usually have your best interests at heart."

If you realize you need help to quit, ask your doctor how to get started. "Therapists and primary care doctors are all trained to recognize alcohol use disorder and help people find appropriate treatment," Dr. Doyle says.

The bottom line

Where does this leave us? There's no perfect answer. But if you're healthy and already drink lightly or moderately, it's probably fine to continue to do so, Dr. Manson says — with some caveats.

"If someone drinks moderately and they're doing well, I don't push them to stop. If, however, they ask whether they should start to drink, or should drink more, to improve their health, the answer would be an emphatic no," Dr. Manson says.

"Many people find that drinking moderately reduces their stress. It's something they enjoy," she adds. "But it shouldn't be perceived as a health-promoting activity."