One report found that having one alcoholic drink a day increased a woman's lifetime risk of breast cancer by 11%, compared with nondrinkers. Two or three drinks per day may increase breast cancer risk by 30 to 40%.

The type of alcohol a woman drinks doesn't seem to affect these predictions.

Whydoes alcohol boost a woman's risk? One theory is that alcohol increases the amount of estrogen in a woman's body. Some research suggests that alcohol users who take hormone replacement therapy (HRT) have a higher risk of breast cancer than those who don't take HRT.

Besides watching their alcohol intake, women who drink should eat plenty of foods high in folate, such as leafy greens, citrus fruits, and whole grains. Alcohol reduces the level of folate in a woman's body, which may further increase her risk of breast cancer.