Abstract  Dietary factors are generally believed to be important determinants of risk of colorectal cancer, but the role of specific micronutrients remains controversial. The potential roles of B vitamins (especially folate and vitamin B6), vitamin D, and calcium are considered. Although much emphasis has been on the potential beneficial role of folate through one-carbon metabolism, recent evidence suggests an additional important role for vitamin B6.

Among micronutrients, the evidence for a benefit is strongest for calcium and vitamin D. Although the Women’s Health Initiative trial did not confirm the calcium and vitamin D hypotheses, critical issues with the design of the trial may have contributed to the null findings. The study of nutrient-gene interactions increases the biologic plausibility of a role of these micronutrients, especially for vitamin D.