Is alcohol healthy? What are the consequences of one beer per week?

Alcohol is not risk-free. The evidence here describes potential risks from alcohol use, but it doesn’t quantify the specific consequences of one beer per week; one beer is roughly 10–12 grams of alcohol in the U.S. 1

• Alcohol-related DNA methylation and gene-expression changes: Alcohol can alter DNA methylation and gene expression, changes associated with increased cancer risk—particularly breast cancer. One estimate cited is a 4–13% increase in breast-cancer risk per 10 grams of alcohol consumed per day. That daily estimate does not directly establish the risk from one beer per week. 2 3
• Neural circuits and habitual behavior: Regular drinking—even once a week, in the example discussed—may strengthen circuits involved in habitual and impulsive behavior, making those behaviors more likely even when a person is not drinking. The example involved several drinks on that occasion, so it does not specify the effect of one beer weekly. 4 5
• Brain atrophy: Chronic alcohol intake was described as relating to reduced cortical thickness and brain volume, with greater intake associated with more shrinkage. The discussion does not quantify the effect of one beer per week. 6
• Fertility: The fertility discussion warns that excess alcohol can impair sperm and egg quality, and recommends limiting intake to one or two drinks per week if drinking; avoiding alcohol is presented as preferable when trying to conceive. It does not identify a specific consequence of one beer weekly. 7