Despite its massive wealth and technological innovations (we’ve got computers on our wrists now!), the United States still lags behind most of the developed world in terms of life expectancy. That’s made a lot of scientists wonder: Why is it that people in France, Italy, and Spain live longer than us? They’ve got bakeries on every block and 24-hour cigarette vending machines to quell their nicotine-addicted populaces. What’s their secret?
So began the research backing this theory. And so began the steady stream of food blog headlines sure to attract wine-lovers. “The 10 Health Benefits of Wine Will Inspire You to Pour a Hearty Glass Tonight,” declares Wide Open Eats. “Science says you should raise your glass. Here’s why wine is actually good for you,” says EatingWell.
But those headlines, while based on real studies, don’t tell the whole story. Wine contains beneficial chemicals, but not in great enough quantities that would benefit your health. And all of those studies that say light-to-moderate drinkers live longer? They make a couple of serious analytical errors. There’s a reason the federal government doesn’t recommend anyone take up drinking—here’s why.
Resveratrol: Wine’s Magic Ingredient?
Much of the hullabaloo over wine’s supposed curative effects is resveratrol. It’s a compound in peanuts, chocolate, and the skins of fruits like blueberries, raspberries, and—you guessed it—grapes. These plants produce resveratrol as a protective measure, in response to injury or if they’re under attack from bacteria or fungi. In the past couple of decades, scientists have found that resveratrol may have preventative and even curative effects for a number of illnesses. Those ailments include diabetes, cancer, heart disease, neurological diseases, and even bacterial infections. So the fact that wine contains resveratrol made a lot of health-conscious wine drinkers very happy.
Sounds like a wonder drug, right? Then why hasn’t your doctor told you about it?
Because almost every study on resveratrol has been conducted in mice and petri dishes—not in humans. So we have a pretty good sense that resveratrol works wonders in tiny rodents. But scientists have yet to confirm whether humans can get those same benefits. Some of the few human trials have been flawed, using grape extracts without measuring the actual concentration of resveratrol. (Resveratrol levels aren’t always consistent in a particular kind of food; they depend on all sorts of environmental factors.) More importantly, we have no idea what dose is both safe and effective. Take too little, and you’d be wasting your money; take too much, and there’s a risk of unpleasant gastrointestinal effects like vomiting and diarrhea.
“But if I drink a glass or two of red wine a day,” you may ask, “won’t I get a slight benefit from resveratrol?” The answer is: probably not. According to Dr. Kenneth Mukamal, a professor at Harvard Medical School, you’d have to drink between 100 and 1,000 glasses of red wine every day in order to get the equivalent amount of resveratrol that’s therapeutic in mice.
In a 2016 review of studies, a pair of German researchers concluded that no combination of wine, grapes, peanuts, or dark chocolate could possibly have enough resveratrol to have any therapeutic effects. One of the more prominent human studies, from 2014, involved about 800 men and women age 65 and older. They hailed from the Chianti region of Italy—an area world-famous for its red wine. The researchers measured the amount of resveratrol in the subjects’ urine, expecting to find more resveratrol in healthier people. But, in fact, the amount of resveratrol had no bearing on the rates of heart disease, cancer, or death.
So there must be some other explanation for Europeans’ longevity. Further research is in the works. But that doesn’t quite settle the question: Is light drinking actually good for you?
Studies Promoting Light-to-Moderate Drinking May Be Flawed
I’m tempted to just link to this Popular Science story and let author Sara Chodosh take it from here. Instead, I’ll summarize her excellent points. Chodosh wrote her piece in the wake of the eye-catching Lancet study from last summer. The study found that alcohol accounted for 10 percent of global deaths among people aged 15-49. The international group of researchers concluded that “the safest level of drinking is none.”
The Lancet researchers recognized that their verdict “conflict[ed] with most health guidelines, which espouse health benefits associated with consuming up to two drinks per day.” There are all sorts of peer-reviewed scientific studies that promote light-to-moderate drinking; here’s one from the Journal of the American College of Cardiology, and here’s a study promoting the health benefits of beer in the American Journal of the Medical Sciences.
But studies can be wrong; even scientists have their blind spots. Chodosh points out “two systematic errors” that have marred alcohol studies for years.
The first: Studies that looked at alcohol’s effect on mortality have long controlled for obvious influencing factors like socioeconomic status whether a person smokes. But they don’t control for why a person stops drinking. Chodosh explains:
An analysis from 2007 by an international group of alcohol epidemiologists and addiction researchers, published in Annals of Epidemiology, notes that “as people progress into late middle and old age, their consumption of alcohol declines in tandem with ill health, frailty, dementia, and/or use of medications.” That decline means that, as people become less well—even if they’re not elderly—they will also tend to stop drinking. So when they enroll in a study on drinking and get lumped into the group of non-drinkers, they’ll artificially inflate the mortality risk—even though their deaths have nothing to do with alcohol abstention. It’s not that teetotaling made them more likely to die during the course of the study; it’s that being closer to death made them more likely to quit alcohol.
That same 2007 analysis found this error in almost every study on whether drinking protects against cardiovascular disease. When researchers only looked at studies that hadn’t committed this error, they couldn’t find any evidence that light drinking was good for the heart.
The second systematic error? Not accounting for why moderate drinkers are particularly healthy. Chodosh spoke with Tim Naimi, a physician and epidemiologist at Boston University School of Medicine and Public Health, to explain.
“People who in their teens or twenties begin to drink, don’t die or become alcoholics, and are able to maintain drinking at low levels—that’s a select group of drinkers,” says Naimi. And that means when epidemiologists go looking at people who are still moderate drinkers in middle age, they’re missing some key people. “If you look at people in midlife who are stable, moderate drinkers, that means they didn’t die from their drinking and they didn’t quit drinking….More than one-third of all deaths from alcohol occur before age 50,” explains Naimi. “That’s typically when people enroll in these cohort studies, but that’s when people who die from alcohol have been picked off.”
In other words, those who make it to middle age without ever developing an alcohol use disorder or dying from some other cause probably don’t owe their lower mortality risk to their drinking. They’re probably the kinds of people who do a lot of other healthy things—like eat well, exercise, and live a life of moderation. It’s likely not their drinking that’s helping them, it’s the other healthy choices they’ve made.
So the next time you have a glass of wine, drink it because you like the taste. You can even drink it because you enjoy the light buzz. But don’t do it because you think it’s good for you.