Does Vitamin E Prevent or Promote Cancer?

The cancer preventive activity of vitamin E has been suggested by many epidemiologic studies. However, several recent large-scale human trials with alpha-tocopherol, the most commonly recognized and used form of vitamin E, failed to show a cancer preventive effect. The recently finished follow-up of the Selenium and Vitamin E Cancer Prevention Trial (SELECT) even showed higher prostate cancer incidence in subjects who took alpha-tocopherol supplementation. The scientific community and the general public are faced with a question: Does vitamin E prevent or promote cancer? Our recent results in animal models have shown the cancer preventive activity of gamma- and delta-tocopherols as well as a naturally occurring mixture of tocopherols, and the lack of cancer preventive activity by alpha-tocopherol. On the basis of these results as well as information from the literature, we suggest that vitamin E, as ingested in the diet or in supplements that are rich in gamma- and delta-tocopherols, is cancer preventive; whereas supplementation with high doses of alpha-tocopherol is not. Cancer Prev Res; 5(5); 701-5. (c) 2012 AACR.