TUESDAY, September 6, 2011 (Health.com) — Middle-aged women who drink alcohol in moderation have a better chance than nondrinkers of staying healthy as they age, especially if they spread out their consumption over most days of the week, a new study from Harvard researchers suggests.
The study followed nearly 14,000 mostly white women beginning in 1976. Compared to teetotalers, those who averaged roughly 3 to 15 alcoholic drinks per week in their late 50s had up to 28% higher odds of being free from chronic illness, physical disability, mental health problems, and cognitive decline at age 70, the study found.
The findings don't necessarily apply to men or to nonwhite women. But they add to the "strong, consistent evidence" that people who drink in moderation are less likely than nondrinkers or heavy drinkers to experience health problems such as heart disease, type 2 diabetes, and dementia, says Qi Sun, MD, the lead author of the study and a nutrition researcher at the Harvard School of Public Health, in Boston.
Experiments have shown that moderate alcohol intake—roughly one drink a day for women, or two a day for men—can reduce inflammation, promote healthy cholesterol levels, improve insulin resistance, and help blood vessels function properly. "Those mechanisms actually underlie a lot of chronic diseases and conditions," Dr. Sun explains.
That doesn't mean that women who don't currently drink should start, however. Other healthy habits, such as staying slim and exercising regularly, are far more important to overall health than alcohol consumption, Dr. Sun says.
"If you are physically active, if you have a healthy body weight at midlife, you can have much better odds of achieving successful aging," he says. "You don't have to use moderate alcohol consumption as a way to help achieve healthy aging."
Moreover, the large questionnaire-based studies that have shown a link between moderate drinking and better overall health—including this one, which was published in the journal PLoS Medicine—have some inherent limitations, says Arun Karlamangla, MD, an associate professor of geriatrics at UCLA's David Geffen School of Medicine.
Unlike clinical trials that compare an active drug to placebo pills, studies like these can't prove that alcohol has a direct effect on long-term health. Sun and his colleagues took into account more than a dozen health and demographic factors that could influence both drinking and aging (such as diet, smoking, educational attainment, and family history of disease), but it's still possible that the moderate drinkers differed in key ways from their peers.
People who drink in moderation "look systematically different than those who...either binge drink or don't drink," says Dr. Karlamangla, who has researched alcohol consumption and disability but was not involved in the new study. And those subtle differences—which might include their social life, eating and exercise habits, and stress levels at home and on the job—may influence overall health independent of alcohol consumption, he adds.
"Even if you buy the idea that alcohol is good for you, we really can't tease out what aspect is good for you from a study like this," Dr. Karlamangla says.
Next page: Spacing out drinks is important
Sun and his colleagues analyzed data from the Nurses' Health Study, a long-running survey of registered nurses. They compared the women's self-reported drinking in middle age—when the women were 58, on average—to their health status at age 70. (The researchers excluded women who had three or more drinks per day and others who showed signs of problem drinking.)
Compared to nondrinkers, a woman's odds of having good overall health later in life increased by 28% if she had one to two drinks per day, and by 19% if she averaged between one-third and one full drink per day. Even having just one or two drinks per week increased a woman's odds of good health by 11%.
When they had their drinks was important, though. Women who drank five to seven days a week had higher odds of being healthy at age 70 than women who drank the same amount in three or four days. And if women concentrated the same weekly alcohol intake to just one or two days a week—to the weekend, say—the association between drinking and better health mostly disappeared.
Women should be aware that even moderate drinking has been linked to an increased risk of breast cancer, Sun says, although he adds that this and other studies suggest that the health benefits of having one drink or less a day seem to outweigh the increase in breast-cancer risk.
The study was "well-done," Karlamangla says, and despite the built-in limitations in the research, it reinforces the evidence for the health benefits of moderate drinking. "I think there's enough data to say that drinking a small glass of wine a day is good for you," he says.