Q: Why do medical experts define moderate drinking as one to two glasses of wine per day?—Veronica, Vail, Colo.
A: In the United States, the Departments of Agriculture (USDA) and Health and Human Services (HHS) recommend that men consume no more than two alcoholic beverages per day, and that women consume no more than one. Those U.S. Dietary Guidelines issued by the federal government also serve as guidelines for medical professionals when they define moderate drinking.
However, exactly how much alcohol constitutes one “drink” varies from country to country, as do dietary guidelines. In the U.S., one “drink” is defined as containing 14 grams (0.6 fluid ounces) of pure alcohol, which equates to 12 ounces of beer (5 percent alcohol by volume), 5 ounces of wine (12 percent ABV) or 1.5 ounces of 80-proof distilled spirits (40 percent).
Both moderate wine consumption and many of the polyphenols found in wine have been linked to myriad health benefits, but excessive consumption of alcohol increases risk for a wide range of health problems. Because of that, the distinction between “moderate” and “excessive” is significant.
According to Harvard's T.H. Chan School of Public Health, this moderate drinking definition sits at the point at which the health benefits of alcohol clearly outweigh the risks, based on hundreds of studies showing an inverse association between light to moderate drinking and risk of heart attack, stroke, peripheral vascular disease, sudden cardiac death and death from all causes.
"The USDA is concerned about long-term health, and there is a clear association between increasing levels of consumption and health risks over time," Dr. Reid Hester, co-founder of research-backed alcohol and substance abuse educational program Checkup and Choices, told Wine Spectator. "The one to two drinks guideline is a function of the long-term risks to one's health in terms of physical diseases, whereas [consuming] three or more [drinks a day] increases risk."
According to the National Institute on Alcohol Abuse and Alcoholism (NIAAA), the gender difference within the U.S. Dietary Guidelines is partly attributed to women having less body water than men of similar body weight, which results in women achieving higher concentrations of alcohol in their blood after drinking equivalent amounts of alcohol to men of the same weight.—Shawn Zylberberg