Selenium and vitamins C and E do not reduce risk of cancer

Results of two large, randomized, placebo-controlled studies have found that supplementary selenium, vitamin C, and vitamin E do not reduce the risk of cancer.

The first study, the Selenium and Vitamin E Cancer Prevention Trial (SELECT), was led by Scott M. Lippman, M.D., of the University of Texas, and Eric A. Klein, M.D., of the Cleveland Clinic Lerner College of Medicine. A total of 35,533 men aged 50 and over were randomly assigned to take either selenium, vitamin E, both, or a placebo pill. SELECT was designed to monitor participants for at least seven years, but was stopped early because the results were so disappointing. The researchers concluded: "In conclusion, SELECT has definitively demonstrated that selenium, vitamin E, or selenium + vitamin E (at the tested doses and formulations) did not prevent prostate cancer in the generally healthy, heterogeneous population.”

For the second study, J. Michael Gaziano, M.D., M.P.H., of Brigham and Women's Hospital and colleagues examined the effects of supplementary vitamin E and vitamin C on prostate cancer and total cancer in 14,641 male doctors aged 50 and over. Results showed that taking vitamin E had no impact on the incidence of prostate cancer, or cancer in general, and that vitamin C had no significant effect on prostate cancer or total cancer. The researchers concluded: "These data provide no support for the use of these supplements in the prevention of cancer in middle-aged and older men."

Lippman SM, Klein EA, Goodman PJ, et al. Effect of Selenium and Vitamin E on Risk of Prostate Cancer and Other Cancers. The Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA. 2009;301(1). doi:10.1001/jama.2008.864

Gaziano JM, Glynn RJ, Christen WG, et al. Vitamins E and C in the Prevention of Prostate and Total Cancer in Men. The Physicians' Health Study II Randomized Controlled Trial. JAMA. 2009;301(1). doi:10.1001/jama.2008.862