Just one alcoholic drink per day—even a teeny one—may not bode well for women on the breast cancer front, reports the Washington Post. That's the conclusion of a large-scale review by the American Institute for Cancer Research and the World Cancer Research fund that took a closer look at 119 studies involving more than 12 million women globally, and the impact of nutrition, diet, and physical activity on breast cancer risk. Although a typical alcoholic beverage contains 14 grams of alcohol, the report finds that even a small glass of wine, beer, or spirits (one with as little as 10 grams of alcohol) is tied to a 5% increased cancer risk in pre-menopausal women and 9% in post-menopausal women, indicating there may be "no level of alcohol use that is completely safe" when it comes to breast cancer, Ann McTiernan, one of the study's lead authors, tells the Post.
Some good news: Researchers also found exercise plays a role in one's risk level—specifically, "vigorous" exercise on a regular basis cut the risk of breast cancer for both pre-menopausal women (a 17% reduction) and post-menopausal women (a 10% cut). So what if you like to throw one back but also often hit the gym? McTiernan notes alcohol increases estrogen levels, which has been tied to breast cancer risk, and that exercise can tamp those levels down—though that doesn't necessarily mean it will cancel out alcohol's effects. Although a healthy lifestyle doesn't offer complete assurance that cancer will stay away—McTiernan compares it to wearing a seatbelt, per the Post—the AICR estimates that a third of US breast cancer cases could be avoided if women kept to a healthy weight, exercised regularly, and didn't drink. (Alcohol has been tied to at least half a dozen types of cancer.)