March 8, 2009

Selenium and Vitamin E Don’t Prevent Prostate Cancer


Selenium and Vitamin E Don’t Prevent Prostate Cancer

According to the results of two large randomized studies, selenium and vitamin E supplements do not reduce the risk of prostate cancer. These results were published in the Journal of the American Medical Association.

Other than skin cancer, prostate cancer is the most commonly diagnosed cancer in U.S. men. In 2008 there were expected to be more than 186,000 new diagnoses of prostate cancer and more than 28,000 deaths from the disease.[1]

Previous studies suggested the risk of developing prostate cancer was reduced among men receiving selenium supplements[2] or vitamin E supplements.[3]

To further explore the relationship between selenium and vitamin E supplementation and prostate cancer risk, researchers conducted two large randomized trials.

The first trial, known as SELECT (the Selenium and Vitamin E Cancer Prevention Trial), enrolled more than 35,000 men from the United States, Canada, and Puerto Rico.[4] At the start of the study, all the men had normal prostate-specific antigen (PSA) levels and a normal digital rectal examination.

Study participants were assigned to one of four groups:

  1. Selenium supplementation
  2. Vitamin E supplementation
  3. Selenium and vitamin E supplementation
  4. Placebo

Study participants have now been followed for over five years, and men in the selenium and/or vitamin E groups do not have lower rates of prostate cancer than men in the placebo group.

The second trial, the Physicians’ Health Study II (PHS II), enrolled more than 14,000 U.S. male physicians.[5] This trial assessed vitamin E and vitamin C supplementation, as well as supplementation with a multivitamin and beta-carotene. The current analysis focuses on the vitamin E and vitamin C results.

Study participants in PHS II have now been followed for an average of eight years. Neither vitamin E nor vitamin C influenced the risk of prostate cancer.

The results of these studies indicate that supplementation with selenium, vitamin E, or vitamin C is not effective for prostate cancer prevention.


[1] American Cancer Society. Cancer Facts & Figures 2008. Available at: (Accessed December 11, 2008).

[2] Clark LC, Combs GF Jr., Turnbull BW et al. Effects of selenium supplementation for cancer prevention in patients with carcinoma of the skin: a randomized controlled trial. Journal of the American. 1996;276:1957-1963.

[3] The Alpha-Tocopherol, Beta Carotene Cancer Prevention Study Group. The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers. New England Journal of Medicine. 1994;330:1029-1035.

[4] 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. Early online publication December 9, 2008.

[5] Gaziano JM, Glynn RJ, Christen WG et al. Vitamins E and C in the prevention of prostate and total cancer in men. The Physician’s Health Study II Randomized Controlled Trial. Journal of the American [early online publication]. December 9, 2008.

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