Eat Dairy Foods, Avoid Breast Cancer?
Study: High-Dairy Diets Linked to Less Risk of Postmenopausal Breast Cancer
Dec. 14, 2005 -- Postmenopausal women who eat lots of dairy products may be less likely to develop breast cancer.
Don't skip over the word "may" in that sentence. It's too soon to declare dairy as protector against breast cancer, the researchers caution.
The study comes from the American Cancer Society's Marjorie McCullough, ScD, RD, and colleagues. It appears in Cancer Epidemiology, Biomarkers, and Prevention.
Women's Diets Studied
McCullough's study included more than 68,000 women, most of whom were white and middle class.
All of the women had completed menopause and didn't have breast cancer when the study started in the early 1990s.
They completed lengthy surveys about their diets and lifestyles. The surveys covered consumption of 68 foods including milk, cheese, yogurt, ice cream, and other dairy products. Most of the dairy products consumed were low fat.
Use of multivitamins and calcium supplements were also noted.
More Dairy Foods, Less Breast Cancer
The women were followed through August 2001. By then, they had had 2,855 cases of breast cancer.
Women who had the highest dietary calcium intake were 20% less likely to have been diagnosed with breast cancer than those whose diets were lowest in dietary calcium.
Calcium isn't only found in dairy products. However, dairy products were the biggest calcium source for women in McCullough's study.
No Link Seen With Supplements
The finding focused on calcium in foods. Use of calcium supplements weren't linked to a lower risk of breast cancer.
Vitamin D, which is also present in dairy foods, wasn't linked with an overall lower risk of breast cancer.
Blood vitamin D levels in people are made up from dietary sources and also from exposure to sunshine. Since levels in the blood were not measured in this study, they only looked at the relationship of breast cancer to the dietary intake of the vitamin.
Other studies cited in this article have suggested that higher levels of vitamin D may lower the risk of breast cancer.
Small Drop in Risk
McCullough is a senior epidemiologist in the American Cancer Society's Epidemiology & Surveillance Research department.