Dairy Intake and Incidence of Common Cancers in Prospective Studies: A Narrative Review
Dairy products are commonly consumed and sometimes recommended by governmental authorities; however, significant evidence indicates that dairy consumption modifies cancer risk. Prospective studies examining the relationship between dairy intake and cancer of the prostate, breast, ovary, and colorectum were reviewed. These studies indicate that dairy consumption is associated with prostate cancer risk, possibly as a consequence of dairy-induced increases in circulating IGF-1 concentrations and the calcium and estrogen content of dairy products. Evidence also suggests a positive association between dairy intake and ovarian cancer. Findings on breast cancer have been mixed; however, recent studies of populations with a wide range of dairy intakes have shown clear associations between dairy intake and breast cancer risk. In contrast, there is a negative association between dairy products and colorectal cancer, which is likely driven by the protective effect of calcium. Current evidence suggests that dairy intake is associated with increased risk of prostate, ovarian, and possibly breast cancer, and reduced risk of colorectal cancer.