A new Chinese study has reported that dietary calcium is associated with reduced breast cancer risk. However, the authors found no link to dairy product consumption. The study was designed to examine the associations between dairy product consumption, calcium intake, and risk of breast cancer. Previous studies have reported conflicting results concerning dairy food consumption and breast cancer risk. The study was conducted from June 2007 to August 2008 and included 438 women with breast cancer cases who were matched to 438 cancer-free controls based on age and residence. Participants were interviewed personally concerning their diets.

Women with the highest fourth of dietary calcium intake were found to have a 65% lower risk of breast cancer than women in the lowest quartile of intake. However, no significant associations were observed between risk of breast cancer and consumption of dairy products. The authors conclude that the results supports a protective effect of high intake of dietary calcium on breast cancer risk, and no association with dairy product intake.

Calcium, diary foods and breast cancer risk

This is one of a number of studies with conflicting results concerning calcium, dairy foods and breast cancer risk. Chinese women tend to have far lower intakes of dairy foods than U.S. women and obtain a higher fraction of their calcium intake from leafy green vegetables and soy foods. Calcium has a complex relationship with breast cancer development that is not well understood. Adequate amounts of calcium are required to realize the chemopreventive benefits of vitamin D and to support bone health. On the other hand, there is some evidence that excess calcium promotes breast cancer. In addition, the saturated fat in dairy products such as milk, cheese and butter and the growth promoters used in the dairy industry have been linked to increased risk of breast cancer. Bottom line: Women should obtain adequate levels of calcium (through foods such as kale, greens and tofu to the extent possible) but avoid high levels. Calcium levels can be monitored over time to correct deficient or excessive levels.