One day, headlines sing the virtues of a glass of Pinot Noir with dinner. The next, they proclaim that no amount of alcohol is safe for anyone. What’s behind this vacillation? And what’s a wine lover to do?
As with most science and health studies—whether they’re talking about eating more oat bran or avoiding fat and sugar—there are no simple, black-and-white answers.
Some recent research links alcohol to various forms of cancer. Mortality experts have also pointed out the dangers inherent in heavy or binge drinking, particularly accidents and violence. But numerous other studies have shown a strong association between light to moderate wine consumption, especially when paired with a healthy diet and regular exercise, and lower rates of cardiovascular disease, diabetes, Alzheimer’s, dementia and respiratory illnesses.
We took a deep dive into the latest research in order to understand scientists’ theories and help explain how you can best incorporate your favorite vino into a healthy lifestyle. Below, find answers to common questions about wine and health (and for more, check out our archive of Health Q&As!).
To get an in-depth look at how wine affects six particular aspects of health, check out the rest of our coverage of the science behind wine and wellness:
- Wine and Your Brain
- Wine and Your Heart
- Wine and Your Weight
- Wine and Time: Aging
- Wine and Women
- Wine and Disease
Q: Why is moderate drinking generally defined as one to two glasses of wine per day?
A: “Moderate drinking sits at the point at which the health benefits of alcohol clearly outweigh the risks,” according to Harvard’s T.H. Chan School of Public Health.
While recommendations vary by country, the consensus of the experts who developed the 2020–2025 U.S. Dietary Guidelines for the Departments of Health and Human Services and Agriculture is that men should consume no more than two alcoholic beverages per day and women should consume no more than one.
Those guidelines define one “drink” as containing 14 grams (0.6 fluid ounces) of pure alcohol, which equates to:
- 12 ounces of beer (5% alcohol by volume)
- 5 ounces of wine (12% ABV)
- 1.5 ounces of 80-proof distilled spirits (40% ABV)
It’s important to note that larger serving sizes and higher-alcohol beverages count as more than one drink (so that generous pour of 14.5% Cabernet is not a single serving).
Moderate wine consumption and many polyphenols found in wine have been linked to myriad health benefits. But medical researchers and professionals agree unequivocally that excessive consumption of any form of alcohol increases the risk for a wide range of health problems over time.—D.N.
Q: Why is there so much conflicting evidence about wine and health?
A: What explains the recent push—from activists, public health officials and media outlets—against any level of alcohol consumption, even light amounts? A lot of the confusion stems from the methodology of health research and the inherent limitations of most alcohol studies, almost all of which are observational (also known as epidemiological). These analyze existing data to determine associations between certain behaviors (say, drinking a glass of wine a day) and specific outcomes (such as lowered LDL cholesterol). Observational studies have been used for decades to determine the health effects of cigarette smoking, diet, exercise and more.
But epidemiological studies have a famous limitation: They establish correlation, not causation, as all Biology 101 students know. Many of them also rely on self-reported data, which is prone to recall bias. People don’t always remember how much they drink, and sometimes they adjust their answers based on how much they think they should be consuming.
And despite researchers’ best efforts to control for confounding variables—lifestyle factors besides alcohol that might skew results—it’s always possible that other aspects of moderate wine drinkers’ behavior could be at least partly responsible for their superior health. Skeptics of wine’s health benefits have seized on this limitation to argue that wine isn’t good for you at all. They insist, rather, that people who drink wine are simply healthier to begin with.
Researchers have long acknowledged that U.S. wine drinkers tend to be more affluent, educated and physically active, with better diets and other health habits than both non-drinkers and people who drink more beer and spirits. If scientists have done their due diligence in controlling for these potentially confounding variables, it’s unlikely that results will be significantly affected by them.
“There is clearly a substantial amount of very high quality data that has demonstrated that a drink a day may actually improve some outcomes,” Gregory Marcus, associate chief of cardiology for research at the University of California San Francisco Medical Center, told Wine Spectator. “Because all of the data on coronary disease and heart attack were based on observational studies, any serious investigator and reasonable clinician knew that confounding [factors] might be at play all along. However, that is a far cry from saying there is clearly no benefit.”
The gold standard of scientific research is the randomized controlled trial, which involves one or more experimental groups and a control group, with people randomly placed in one group or the other. In a typical study design, experimental subjects are assigned the variable being tested, whether a new drug or a behavioral modification (such as drinking a glass of wine with dinner). These studies are randomized, which removes the possibility of bias, and they measure the effect of a single variable while precisely controlling for confounding factors. But controlled trials are expensive, time-consuming and logistically complex. They also present ethical challenges that observational studies don’t—namely, if drinking may be harmful, should researchers encourage a large group of people to imbibe?
Another challenge is that controlled trials tend to measure limited periods of time. Most researchers who believe there are benefits in light to moderate drinking believe those are long-term benefits.
Is there hope for a randomized controlled trial on moderate drinking in the near future? Marcus believes that he and a team of collaborators across the country have a feasible design. But they haven’t been able to secure funding. Marcus and his colleagues believe it’s possible that “there are more concerns about optics than there are actual scientific or even ethical concerns.” Research is often funded with the hopes of developing new, profitable medicines. No one sees much reason to invest in research that might encourage people to drink.
Marcus is not giving up. He believes there is a strong need for such a trial to better establish how moderate drinking compares to abstinence: “There is nowhere else in medicine where we would tolerate such weak data to make such firm conclusions.”—K.M.
Q: What exactly are polyphenols? And which wines have them?
A: Polyphenols are organic chemicals found in plants. They get their name from their structure: A “phenol” is a type of chemical compound; “poly” means more than one of those compounds make up the molecule. There are thousands of different types of polyphenols that exist naturally in plants and they play a variety of roles, from helping create pigment (which gives grapes and wines their colors) to providing protection against ultraviolet radiation to repairing physical damage, depending on the specific needs of each plant type.
Wine’s polyphenols come from grapes, mainly from the skins, and because making red wine involves more extended contact with the grape skins, those wines tend to contain a lot more polyphenols than white wines do. As a whole, red wine’s polyphenolic content has been praised by wellness-conscious drinkers, but white wines offer some polyphenolic health benefits too.
The amount and type of polyphenols found in wine varies widely. Wines that are dark in color and high in tannins have been shown to naturally have higher-than-average levels of polyphenols. But it depends on the compound—studies have shown that Pinot Noir, a lighter, less tannic grape, has high levels of resveratrol. A wine’s polyphenol content also depends on where the grape is grown and how the wine is made.
As for which polyphenols provide the most health bang for your buck, scientists believe variety is key, and that people should consume different kinds. Wine, coffee, tea, berries, leafy greens, nuts and even chocolate all provide a healthy dose of various polyphenols.—K.M.
Q: Can avoiding alcohol for a month actually improve your health?
A: All of us need to be mindful about what we drink, when and how much. The idea behind Dry January and other calls to give up drinking for a month is that they offer people a chance to reassess their relationship with alcohol. Certainly, some people should not drink; they should consult physicians and alcohol-recovery groups for help.
If you’re prone to overindulging and aren’t feeling your best, abstaining in the short term may offer benefits. Proponents tout better sleep, healthier skin, more energy and a clearer mind; plus, a month off can give the liver time to recover and generate new cells. But Dry January isn’t a pass to substitute unhealthy treats in place of alcohol or to binge drink come February 1.
Ultimately, experts agree that having a dry month can be beneficial, but it’s not the only way—nor the best way—to develop or maintain healthy drinking habits. For decades, the prevailing wisdom has been that moderation in all things is key to a healthy life. If you’re already exercising regularly and eating a balanced diet, and you enjoy a glass of wine with dinner or while socializing, abstaining for a month likely won’t help much. Plus, finding pleasure in life brings its own health benefits.—D.N.
Q: Can a glass of wine before bed help me sleep?
A: Yes and no. Since alcohol has sedative effects, you’ll get drowsy and fall asleep more quickly. But studies have found that alcohol also disrupts your sleep patterns and causes you to wake up more often during the night. (Don’t forget, it’s also a diuretic.) Plus, drinking worsens snoring and sleep apnea. The end result: You won’t feel rested when you wake up. Expert tip: Wait more than one hour per drink before going to bed. Never use alcohol as a sleep aid (that can lead to dependency) and never mix it with sleep medication, including melatonin.—D.N.
Q: Can wine prevent COVID-19 and other respiratory infections?
A: While heavy drinking can damage the lungs and weaken the immune system, there’s growing evidence that moderate wine consumption may improve respiratory health and even protect against certain infections, including COVID-19.
A 2022 study of people 49 and older in the U.K. found that those who drank one to two glasses of red wine per day were 10% to 17% less likely to contract COVID-19 than non-drinkers. White wine drinkers who consumed five glasses per week or less had a 7% to 8% lower risk. On the other hand, people who drank five or more hard alcohol drinks per week, as well as frequent beer or cider drinkers, had an elevated risk of getting COVID-19.
The researchers concede the possibility that factors such as income, diet and exercise may have played a role in wine drinkers’ reduced risk, but they also hypothesized that red wine polyphenols may bolster the immune system.
In 2002, one study found that people who consumed 14 glasses of wine per week were half as likely to develop a cold than those who drank beer, spirits or no alcohol at all. Doctors advise against consuming high amounts of alcohol if you’re already sick; it can aggravate your sinuses, disrupt sleep and burden your immune system. For that reason, excessive consumption after a vaccination also isn’t a good idea. However, in either case, one or two glasses of wine isn’t likely to negatively impact recovery.
Though our understanding of alcohol’s effects on respiratory health is still developing, current science suggests that moderate wine drinkers can breathe easy.—K.M.
