Song M, Lee IM, Manson JAE, et al. - Researchers sought to determine how vitamin D supplementation influence the risk of colorectal adenomas and serrated polyps in a prespecified ancillary study of a large-scale prevention trial (the vitamin D and omegA-3 trial, VITAL) of individuals who were free of cancer and cardiovascular disease at enrollment. In VITAL trial, either dietary supplements (2000 IU vitamin D3 and 1 g marine n-3 fatty acid) or placebo were provided daily to 25,871 adults with no history of cancer or cardiovascular disease (12,786 men 50 y or older and 13,085 women 55 y or older). Conventional adenomas were documented in 308 cases in 12,927 participants in the vitamin D group and 287 cases in 12,944 participants in the placebo group during a median follow-up of 5.3 years. Outcomes suggest no correlation of daily vitamin D supplementation (2000 IU) with risk of colorectal cancer precursors in average-risk adults not selected for vitamin D insufficiency.