Does Vitamin E Prevent or Promote Cancer?

The cancer preventive activity of vitamin E has been suggested by many epidemiological studies. However, several recent large-scale human trials with α-tocopherol, the most commonly recognized and used form of vitamin E, failed to demonstrate 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 α-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 demonstrated the cancer preventive activity of γ- and δ-tocopherols as well as a naturally occurring mixture of tocopherols, and the lack of cancer preventive activity by α-tocopherol. Based on 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 γ- and δ-tocopherols, is cancer preventive; whereas supplementation with high doses of α-tocopherol is not. Vitamin E Consists of Different Forms of Tocopherols and Tocotrienols Vitamin E is a group of fat-soluble antioxidant nutrients consisting of tocopherols an