A new study has suggested that intake of dairy milk is associated with a greater risk of breast cancer in women.
The study, done at Loma Linda University Health, found that even relatively moderate amounts of dairy milk consumption can increase women’s risk of breast cancer — up to 80% depending on the amount consumed.
The authors of the study said that fairly strong evidence suggested that either dairy milk or some other factor closely related to drinking dairy milk is a cause of breast cancer in women.
“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%,” Fraser said. “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%,” the paper said.
Dietary intakes of nearly 53,000 North American women were evaluated for the study, all of whom were initially free of cancer and were followed for nearly eight years. By the end of the study period, there were 1,057 new breast cancer cases during follow-up. No clear associations were found between soy products and breast cancer, independent of dairy. But, when compared to low or no milk consumption, higher intakes of dairy calories and dairy milk were associated with greater risk of breast cancer, independent of soy intake. Fraser noted that the results had minimal variation when comparing intake of full fat versus reduced or nonfat milks; there were no important associations noted with cheese and yogurt.
The study said the possible reasons for these associations between breast cancer and dairy milk may be the sex hormone content of dairy milk, as the cows are of course lactating, and often about 75% of the dairy herd is pregnant. Breast cancer in women is a hormone-responsive cancer.