This placebo-controlled double-blind study carried out by the Harvard Medical School investigated whether long-term multivitamin supplementation decreases the risk of cancer among men. 14,641 men aged 50 years or older, including 1312 men with a history of cancer, were included. In the study of 14 years, participants were given daily doses of a multivitamin supplement or a placebo. Daily multivitamin use was found to significantly reduce the occurrence of cancer. It was therefore concluded that daily multivitamin supplementation reduces cancer risk. For more details, please see the study.
Debra L Barton, Gamini S Soori, Brent A Bauer, Jeff A Sloan, Patricia A Johnson, Cesar Figueras, Steven Duane, Bassam Mattar, Heshan Liu, Pamela J Atherton, Bradley Christensen, Charles L Loprinzi