Does vitamin E prevent or promote cancer?
Study Goal
The researchers aimed to evaluate the cancer preventive effects of different forms of vitamin E, including α-tocopherol, γ-tocopherol, and δ-tocopherol, based on findings from the Selenium and Vitamin E Cancer Prevention Trial (SELECT).
Results Summary
The study found that α-tocopherol supplementation was associated with higher prostate cancer incidence, while γ- and δ-tocopherols and a natural mixture of tocopherols showed cancer preventive activity in animal models. The results suggest that the form of vitamin E is critical for its cancer preventive effects.
Population
Human subjects from the SELECT trial and animal models.
Effective Dosage
Not specified
Duration
Not specified
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
vitamin E | no change | cancer preventive activity | - | - | has been suggested by many epidemiologic studies | #1 |
α-tocopherol | no change | cancer preventive effect | human trials | - | failed to show | #2 |
α-tocopherol supplementation | increase | prostate cancer incidence | subjects who took α-tocopherol supplementation | - | showed higher | #3 |
γ- and δ-tocopherols | no change | cancer preventive activity | animal models | - | have shown | #4 |
naturally occurring mixture of tocopherols | no change | cancer preventive activity | animal models | - | have shown | #5 |
α-tocopherol | no change | cancer preventive activity | animal models | - | lack of | #6 |
vitamin E, as ingested in the diet or in supplements that are rich in γ- and δ-tocopherols | no change | cancer preventive | - | - | is | #7 |
supplementation with high doses of α-tocopherol | no change | cancer preventive | - | - | is not | #8 |
The cancer preventive activity of vitamin E has been suggested by many epidemiologic studies. However, several recent large-scale human trials with α-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 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 shown 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. 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 γ- and δ-tocopherols, is cancer preventive; whereas supplementation with high doses of α-tocopherol is not.