Fermented dairy products, calcium, and colorectal cancer in The Netherlands Cohort Study

Experimental studies suggest that an increased consumption of fermented dairy products and calcium might decrease the risk of colorectal cancer. The associations between fermented dairy products, dietary calcium, and colorectal cancer risk were investigated in a population with a wide variation in intake of dairy products. The Netherlands Cohort Study of diet and cancer started in 1986 when 120,852 Dutch men and women, ages 55-69, filled out a questionnaire concerning dietary patterns and lifestyle. The present analysis is based on 3.3 years of follow-up and includes 215 incident cases of colon cancer and 111 incident cases of rectal cancer, excluding cases diagnosed in the first year of follow-up. After adjustment for potential confounding variables, colorectal cancer risk was weakly inversely associated with the consumption of fermented milk [relative rate (RR) in the highest category of intake compared to nonusers, 0.89; 95% confidence interval (CI), 0.60, 1.33], unfermented milk (RR, 0.86; 95% CI, 0.57, 1.29), and cheese (RR, 0.88; 95% CI, 0.59, 1.33). However, category-specific relative rates and tests for trends were not statistically significant. For fermented milk, the inverse association was limited to colon cancer (RR, 0.70; 95% CI, 0.43, 1.15; trend, P = 0.33). In crude and multivariate models, total dietary calcium intake (highest versus lowest quintile, RR, 0.92; 95% CI, 0.64, 1.34) and calcium from fermented dairy products (RR, 1.14; 95% CI, 0.77, 1.68) were not significantly associated with colorectal cancer risk. Calcium from unfermented dairy products was inversely associated with rectal cancer risk (RR, 0.55; 95% CI, 0.30, 1.04; trend, P = 0.03). After 3.3 years of follow-up, these data are not consistent with a substantially decreased risk of colorectal cancer with increased intake of fermented dairy products and dietary calcium.