Red Meat Linked to Breast Cancer

While factors such as age, gender, family history, and obesity are known to increase the likelihood of breast cancer, a new study finds that higher red meat intake during young adulthood could be another risk factor for the disease.  

The study, led by researchers at the Harvard School of Public Health, sought to investigate the connection between dietary protein sources in early adulthood and the risk for breast cancer. To do so, the authors analyzed data from 88,803 pre-menopausal women, aged 26 to 45, culled from a questionnaire on diet completed as part of the Nurses’ Health Study II in 1991.
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The Harvard researchers provided an updated analysis of data from that study, with a longer follow-up period, approximately 3 times as many breast cancer cases, and additional paths of investigation. In addition, the researchers examined the link between breast cancer and other protein-rich foods.

The diet questionnaire used listed different types of food against 9 categories of intake frequency, ranging from “never or less than once per month” to “6 or more times a day,” with foods including unprocessed and processed red meats, poultry, fish, legumes, and nuts, as well as foods commonly consumed from 1960 to 1980, when participants would have been high school students. Other factors such as weight, height, personal and family history, race, and smoking habits were also considered.

Throughout 20 years of follow-up, the authors identified 2,830 cases of breast cancer, and found that a higher intake of red meat products during early adulthood was associated with a 22% greater risk of breast cancer. In contrast, a higher intake of poultry during early adulthood was linked to a lower incidence of breast cancer in post-menopausal women.

While substituting poultry for red meat could lessen the risk of breast cancer, there are likely other benefits to limiting red meat intake and replacing it with other protein sources, such as reducing the risk of diabetes and heart disease, says Maryam Farvid, PhD, associate professor in the department of nutrition at the Harvard Public School of Health, and lead study author.

“Each additional serving per day increase in total red meat was associated with a 13% increase in risk of breast cancer,” says Farvid. “Having two servings per day red meat that are common in the U.S. would increase the risk by 26%.”

“Our choices about diet should be made considering all important health outcomes,” adds Walter Willett, PhD, MD, MPH, a professor of epidemiology and chair of the department of nutrition at the Harvard School of Public Health, and a co-author of the study.

“Limiting red meat intake, and instead consuming a combination of nuts, beans, soy, fish, and poultry as alternative protein sources has been associated with lower risks of heart disease and diabetes,” says Willett. “The new study provides evidence that this will also help reduce risk of breast cancer. Other ways to keep risk of breast cancer low are to limit consumption of alcohol, stay active and fit, and avoid weight gain during midlife.”

—Mark McGraw

Reference

Farvid M, Cho E, et al. Dietary protein sources in early adulthood and breast cancer incidence: prospective cohort study. BMJ. 2014.