At least seven prior studies have linked prostate cancer risk to intake of dairy foods, but the roles of different components, such as calcium, vitamin D and other potential constituents, are unclear.

Reporting in the American Journal of Clinical Nutrition, Tseng and colleagues at the National Cancer Institute studied the relation of dairy intake to prostate cancer risk in 3,612 men with a mean age of 57 years who were followed in NHANES (National Health and Nutrition Examination Survey) surveys from 1982-1992.

Over this 10-year span, there were 131 new prostate cancer diagnoses among the group. Dietary surveys indicated that the risk of new prostate cancer was associated with increased consumption of calcium from low-fat milk, but not whole milk, and there was a nonsignificant association with low intakes of vitamin D.

A plausible hypothesis is proposed that increased calcium suppresses concentrations of vitamin D, which is less prevalent in low-fat milk. Others have related increased cancer risk to vitamin D deficiency. (See American Journal of Clinical Nutrition, 2003;77:204-10 for a more detailed presentation of the inadequacy of vitamin D in the American diet.)

The study points to the need for more detailed investigations into the potential roles of vitamin D deficiency and calcium excess in prostate cancer risk in the current era, in which prostate-specific antigen testing detects many more cases, and in the context of recommendations for increased calcium consumption for the prevention of osteoporosis in aging men and women (Tseng M, Breslow RA, Graubard BI, et al., “Dairy, calcium, and vitamin D intakes and prostate cancer risk in the National Health and Nutrition Examination Epidemiologic Follow-up Study cohort.” Am J Clin Nutr, 2005;81:1147-54)