In a study of 14,641 male physicians, the use of multivitamins were followed for a randomized, double-blind, placebo-controlled trial. During a median follow-up of 11.2 years, there were 2669 men with confirmed cancer, including 1373 cases of prostate cancer and 210 cases of colorectal cancer. Compared with placebo, men taking a daily multivitamin had a statistically significant reduction in the incidence of total cancer, estimated at a 27% reduced risk. In conclusion, the researchers wrote:
“In this large prevention trial of male physicians, daily multivitamin supplementation modestly but significantly reduced the risk of total cancer.”