Many studies support a link between drinking alcohol and an increased risk of breast cancer. One pooled analysis of data from 53 studies found that for every one alcoholic drink consumed per day, the relative risk of breast cancer increased by about seven percent (a 1.07-fold increase in risk) [126]. Overall, women who have two to three alcoholic drinks per day have a 20 percent greater risk of breast cancer (a 1.2-fold increase in risk) than non-drinkers [133].
Alcohol may increase breast cancer risk in a number of ways. It can change the way a woman's body metabolizes estrogen (how estrogen works in the body) [134]. Alcohol causes blood estrogen levels to rise, which may in turn increase the risk of breast cancer. (Learn more about estrogen and breast cancer risk.) Drinking alcohol can also reduce blood levels of the vitamin folic acid. Folic acid plays a role in copying and repairing DNA. Low levels folic acid may make it more likely that DNA is incorrectly copied when cells divide. Such errors can lead cells down a pathway to become cancerous.
No one should drink a lot of alcohol. For those who do drink some alcohol, getting enough folic acid (often called folate on nutrition labels) may help reduce the extra breast cancer risk linked to drinking alcohol [135-137]. Although not all studies show this benefit [138-140], getting enough folic acid is part of a healthy lifestyle. Taking a daily multivitamin is a good way to get folic acid. Oranges, orange juice, green leafy vegetables and fortified breakfast cereals are good food sources of folic acid.
Updated 11/09/09
