Lippman SM et al. (2009) Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA 301: 39–51

Gaziano JM et al. (2009) Vitamins E and C in the prevention of prostate and total cancer in men: the Physicians' Health Study II randomized controlled trial. JAMA 301: 52–62

The results of two large clinical trials, which assessed the effects of antioxidant supplementation on cancer in men, have found no protective effect from vitamins C and E and selenium. These results are contrary to previous studies, which indicated that antioxidant supplements might reduce cancer risk or mortality.

In the Selenium and Vitamin E Cancer Prevention Trial (SELECT), consisting of 35,533 men from the US, Canada and Puerto Rico, Lippman and colleagues investigated the effects of supplementation with vitamin E (400 IU per day all rac-α-tocopheryl acetate) and/or selenium (200 µg per day L-selenomethionine). A data review after a median follow-up of 5.46 years revealed that vitamin E or selenium, taken individually or in combination, did not prevent prostate cancer.

Gaziano et al. reported the outcomes of the Physicians' Health Study II, which assessed the effects of vitamin C (500 µg per day synthetic ascorbic acid) and vitamin E (400 IU synthetic α-tocopheryl every second day) supplementation in 14,641 male physicians. After a mean follow-up of 8 years, neither vitamin was seen to affect the risk or outcomes of any cancer, including prostate cancer.

The authors of both trials suggest that antioxidant supplementation at the tested doses is not recommended for cancer prevention, and encourage further research to identify alternative agents that might help to prevent prostate cancer and other cancer in men.