Estrogen seems to be the culprit. Studies have shown that alcohol temporarily increases estrogen concentrations in the blood, and elevated estrogen levels are associated with breast cancer. This effect has been shown to be more pronounced among women using estrogen replacement therapy. While additional studies are needed, the message is clear: "Avoiding alcohol is one way a woman can reduce her risk of breast cancer," says Michael J. Thun, M.D., head of epidemiological research for the American Cancer Society.
Postmenopausal women, however, often have a greater risk of dying from heart disease or stroke than from breast cancer. One drink a day (especially red wine) has been shown to reduce the risk of cardiovascular disease by up to 40 percent. The net result is that people who consume a glass of alcohol per day may live longer than nondrinkers. Because every woman must weigh the costs and benefits of drinking based on her own family history, age and risk of disease, it is impossible to make - a blanket statement about how much is too much.
There are, of course, other health consequences to consider. Alcohol is primarily processed in the liver (which puts that organ at the greatest risk), but it can also work its way into the reproductive system, the skin, eyes, bones, breasts, breast milk and the fetus. "Because alcohol is a very small molecule, just slightly bigger than water, it can get inside every cell," says Sheila Blume, M.D., a psychiatrist who has researched alcohol's effects on women. "Almost any organ in the body can be affected." And then there is the troubling, if not life-threatening, matter of weight gain. A four-ounce glass of wine contains about 120 calories, a shot of vodka packs 105, and 12 ounces of beer has 150. You'd think twice about ordering crème brûlée for dessert but nothing of downing three drinks with dinner.
The good news (and by now you need some) is that drinking in and of itself does not lead directly to alcoholism. "Most people who start smoking socially will become addicted, but the same isn't true of alcohol," says George E. Vaillant, M.D., author of The Natural History of Alcoholism and director of research in the department of psychiatry at Brigham and Women's Hos-pital in Boston. In that sense, drinking is more analogous to food than it is to a drug. Some people feel obese when they gain an inch at the waistline, while others don't. An individual must determine the right level of consumption for herself.
For most people, experimentation comes in the teens and early twenties. "I was into partying in college, where drinking and socializing went hand in hand," says Brittany Marr, a 23-year-old from Boulder, Colorado. "Though I had a good time, I was tired and lacked the desire to eat well and exercise. Finally, I cut back and started to feel like myself again."
Many women feel they can drink less than they used to. "I noticed my inability to recoup. Instead of a few hours to get rid of my hangover, it took a couple of days," says Robin Stefko, 36, who e-mailed from Marion, Illinois, to tell us that she now alternates drinks with glasses of ice water and no longer wakes up feeling as though she's been "hit by a semi-truck." Being able to drink less than before is, in fact, a good sign. People with drinking problems generally develop a higher tolerance for alcohol.