One minute you’re feeling festive and the next you’re wishing you’d had one less drink. This spring, a pair of studies sent equally mixed signals about long-term alcohol consumption that might baffle even the most sober teetotaler.A survey of more than 1 million middle-aged British women linked low to moderate alcohol intake with an increased risk of certain cancers, researchers reported in the March Journal of the National Cancer Institute (JNCI). In the same month, a study in the Journal of the American Geriatrics Society (JAGS ) upheld the oft-quoted result that one alcoholic drink a day actually reduces the risk of death among people over 55.
The results may seem confusing for women trying to decide how much to drink or if they should drink at all, says Naomi Allen, a cancer epidemiologist at the University of Oxford in England and the lead author of the JNCI report.
Allen and her colleagues at the university looked at data from the Million Women Study, a study of British women who answered questionnaires at routine breast screenings between 1996 and 2001. The researchers followed the women for more than seven years and found that those who had one alcoholic drink a day experienced an additional 15 cases of cancer in the mouth, throat, esophagus, breast, liver and rectum per 1,000 women, compared with women who didn’t have a daily drink; two drinks a day correlated with 30 extra cases per 1,000 women. The strongest link was to breast cancer. While an extra drink appeared to decrease the risk of thyroid cancer, non-Hodgkin lymphoma and renal cell carcinoma, the overall risk of developing cancer still grew for women who drank two or three drinks a day instead of just one or two.
In the second study, in JAGS, researchers conducted telephone interviews in 2002 with more than 12,500 U.S. residents over 55 and checked up on them in 2006. After accounting for various factors such as socioeconomic status, which previous research has shown to be associated with mortality, the researchers found evidence that a drink a day reduced the risk of death within those four years.
The take-away message from the research depends on a person’s individual situation, the researchers point out. “Whether alcohol is going to be helpful or harmful to you depends on [your] baseline risk,” for diseases affected by alcohol, says Sei Lee, a geriatrician at the University of California in San Francisco who is the lead author of the JAGS study. For instance, says Oxford cancer epidemiologist Valerie Beral, a co-author on the JNCI study, middle-aged women generally have a higher risk of cancer than heart disease, so alcohol may be more harmful for them than for men or older women, who are more prone to heart disease.
The Oxford team did not directly address whether alcohol affected death rates—something the team says it plans to do. Another future step, Lee suggests, would be to study other patient populations to determine if the results apply to women who don’t receive breast cancer screenings.
For now, Lee says that he’ll continue advising his patients to follow U.S. government guidelines, which state that an alcoholic drink a day is probably OK for most women. But the answer is “not straightforward,” he admits. Beral agrees: “There aren’t simple messages about alcohol.”