You could forgive the average woman for being confused about how much alcohol she should be drinking, or even whether she should be drinking at all. Headlines over the last decade have linked moderate alcohol consumption to everything from a higher risk of breast cancer to a lower risk of dementia. Even the notion that pregnant women should never drink may be debatable. Just this month, a British study suggested that binge drinking—on a very occasional basis—might not be harmful to the fetus (though researchers cautioned that more investigation was needed).
As doctors continue to sort through the contradictory evidence, one thing remains certain: decisions about drinking are more loaded for women than for men. "The benefits of alcohol are going to vary by individual, depending on genes and lifestyle," explains Samir Zakhari, director of metabolic research at the National Institute of Alcoholism and Alcohol Abuse. "But the risks--which we know much more about—those clearly vary by gender, and are much higher for women." Here's what we know—and don't—about how alcohol affects the female body:
1. Gender Benders
The differences between men and women can be stark when it comes to the way alcohol affects them. For example, if two people, of opposite genders but equal weight drink the same amount and type of alcohol, the woman will get drunker, and stay that way longer.
The reasons come down to basic physiology. Alcohol passes through the digestive tract and is dispersed in the body's water. Because women always have less water in their bodies, the alcohol is less dilute for them. Women's bodies also produce less alcohol dehydrogenase (ADH)—the molecule responsible for breaking alcohol down so that the body can eliminate it. Less water and less ADH means more alcohol stays in the body, for longer periods of time. "It's like taking the same amount of alcohol and putting it into a much smaller glass," explains Michael Charness, a Harvard Medical School neurologist.
This biologic difference not only means that women have to be careful during those infamous college drinking games, but long-term, women are more likely than men to develop alcohol-related liver disease and brain damage. And women are just as likely to develop alcohol-related heart diseases as men, even though they still tend to drink less alcohol over a lifetime.
Intoxicated women are also far more likely to be the victims of date rape or sexual assault than men. And they are more prone to alcohol-induced blackouts, which can make reporting such attacks difficult.
2. The Wine Myth
One of the biggest misconceptions that women fall prey to is the idea that wine is a safer, healthier choice than the fattening, masculine beer we see in commercials. While wine has some appealing ingredients that other alcoholic beverages do not, (namely a group of antioxidants called polyphenolic compounds that come from grape skin), most experts say it's a myth that wine is healthier. All the risks and benefits of an alcoholic beverage come from the alcohol itself," says Zakhari, explaining that the alcoholic content of wine far outweighs the amount of these other ingredients. "So it doesn't really matter whether it's beer or wine or something else."
3. Breast Cancer Caveat
As for the much-studied link between alcohol and breast cancer, no one can say for certain whether one has anything to do with the other. While research reported at September's European Cancer Conference indicated that women who drank heavily (three glasses a day or more) faced a 30 percent higher risk of breast cancer, numerous other studies over the last decade have shown the opposite—that there is no correlation between alcohol and breast cancer. "The studies have been all over the place," says Zakhari. "The bottom line is that we aren't sure, and women who are genetically predisposed to breast cancer should probably drink less if they want to be on the safe side."
4. The Third Trimester
It's no secret that drinking while pregnant can seriously threaten the health of your unborn child—the risk of fetal-alcohol syndrome (FAS) has long been tied to alcohol consumption during the first trimester of pregnancy, when organs and body features are still developing. That being said, many if not most mothers report being cleared by their doctors for a glass of wine or two once they reach the third trimester—and some evidence suggests that as many as 10 percent of pregnant women drink moderately. Now researchers say that FAS-associated brain damage may result from drinking at any point during a pregnancy, including the final weeks.
How much drinking puts an unborn child at risk has divided the American medical community from its European counterpart for decades. While the United States has adopted a precautionary approach, advising women who are or might become pregnant not to drink at all, Europeans have traditionally condoned a couple of drinks towards the end of a pregnancy. This can lead to confusion (and make Americans seem like prudes to their European friends). But with the French now putting warnings about drinking during pregnancy on their wine, those continental attitudes seem to be changing.
5. Drink and Live Longer?
More research is needed before doctors can say for certain whether alcohol does in fact reduce your chances of suffering from type-2 diabetes or dementia. But most experts do agree that a drink a day can offer at least some protection against cardiovascular disease. "The main benefit of alcohol that we can state with any degree of certainty is that it counteracts the narrowing of coronary arteries that comes with age," says Cynthia Bearer, a physician and associate professor at Case Western Reserve University in Ohio "That benefit is going to be seen really only in the older population—people over 50."
With that bit of certainty comes another conundrum: aging also reduces our tolerance for alcohol, most likely by reducing the amount of water in our bodies. Studies have shown that older adults of both sexes reach higher blood-alcohol levels than younger adults who drink the same amount. So reaching the half-century mark doesn't necessarily mean you should party like a rock star. Moderation is still key, at any age.
What's a Wise Woman to Do?
Take a look at the official guidelines and compare them honestly to your own consumption. The U.S. Department of Health and Human Services (HHS) defines moderate drinking as no more than one drink a day for women, and no more than two drinks a day for men. According to a report by the National Institute of Alcoholism and Alcohol Abuse (NIAAA), 13 percent of women who drink surpass this one-drink cut off. And roughly 5.3 million women in the United States drink in a way that threatens their health and safety. "I don't think this means that women are over-estimating the benefits of drinking," Zakhari says. "But people who want to drink may use [the reported benefits] as a way to justify their choices."
While the potential benefits of moderate drinking may be equal for both sexes, the risks are higher for women, which means that women need to be more cautious than men at the bar or liquor store. Those with a family history of breast cancer or alcoholism should probably head for the soft-drink aisle instead. Bottom line, says Zakhari: "If you want to drink for pleasure and you can do it in moderation, that's fine. If you want to drink to combat coronary heart disease, well, there are safer, cheaper and more effective ways of doing that." The most obvious examples are diet and exercise, and for osteoporosis, make sure you are getting enough calcium.