In a recent study published in the January issue of the Anals of Internal Medicine, professor Miller and collegues from John Hopkins University have suggested that high doses of vitamin E (defined by the authors as greater than 400 iu per day for 1 year or more) increased the risk of death. The risk difference was 39 more deaths per 10,000 people in the high dose vitamin E group. In the low dose group the risk level was 16 fewer deaths per 10,000 people, however this was considered not statistically significant.

The authors do caution however, that the high dosage trials were small and performed on patients with chronic diseases and they stated that “precise estimation of the threshold at which risk increases is difficult.”

The study should have emphasized that most of the clinical trials used synthetic alpha-tocopherol form of vitamin E. There are differences in the properties of the natural and synthetic forms of vitamin E. Vitamin E exists naturally in eight forms that have different potencies, kinetics, and health effects in the human body.

Vitamin E has valuable antioxidant activities and is particularly useful in protecting the cell membrane from lipid peroxidation. The Foods Standards Agency suggests 536mg as a safe upper limit for unsupervised supplementation. The jury is still out on the long term effects of high dose vitamin E, and further research is needed.

American Chemical Society: www.chemistry.org

Miller ER, Barriuso RP, Dalal D et al: Meta-Analysis: High-Dosage Vitamin E Supplementation May Increase All-Cause Mortality . Anals of Internal Medicine 2005 :142 (1).