Got Milk? Study Finds Potential Link Between Dairy Intake and Breast Cancer
Posted: Monday, May 11, 2020
Daily consumption of dairy milk, but not soymilk, was found to be correlated with a higher risk for breast cancer, according to an observational study in the International Journal of Epidemiology. Gary E. Fraser, MBChB, PhD, of Loma Linda University Health, and colleagues also observed a protective association in soy, which may serve as a dairy milk substitute.
“Consuming as little as 1/4 to 1/3 cup of dairy milk per day was associated with an increased risk of breast cancer of 30%,” Dr. Fraser said in an institutional press release. “By drinking up to one cup per day, the associated risk went up to 50%, and for those drinking two to three cups per day, the risk increased further to 70% to 80%.”
From 2002 to 2007, researchers followed 52,795 U.S and Canadian female participants who were initially cancer-free and 30 years or older for 7.9 years. Baseline questionnaires were used to self-report the following factors: demographics, family history of breast cancer, physical activity, alcohol consumption, use of medications (anthropometrics and hormonal), breast cancer screening, and reproductive/gynecologic history. Dietary assessment was estimated by food frequency questionnaires surveying participants’ soy, dairy, meats, nuts, and seeds intake.
After 7.9 years, there were 1,057 incidents of breast cancer, with 906 cases found in postmenopausal women and 121 cases in premenopausal women. Excluding soy, low to moderate dairy milk intake was linked with a high breast cancer risk (hazard ratio [HR] = 1.50; P < .001). Dairy milk intake was also correlated with a higher risk for estrogen receptor–positive breast cancer (HR = 1.36; P = .008) and progesterone receptor–positive breast cancer (HR = 1.45; P = .003). Results showed little variation between the type of dairy milk (full fat vs. reduced vs. nonfat). Substituting a median intake of dairy milk with soy milk showed a lower risk for breast cancer (HR = 0.68; P = .001). Yogurt and cheese appeared to have no major association with breast cancer risk.
Disclosure: For full disclosures of the study authors, visit academic.oup.com.