JUN 02, 2008
This analysis of the Women's Health Study found that vitamin E supplementation for an average of 9.7 years had no beneficial or harmful effect on risk of cataract.
Five previous trials have examined vitamin E supplementation in cataract prevention, but they involved only three to about six years of treatment. The Women's Health Study offered a unique opportunity to investigate the 10-year occurrence of age-related cataract in a large trial of vitamin E use among healthy females age 45 or older.
Women assigned to the vitamin E group had an insignificant 4 percent lower risk of cataract, and the 95 percent CI around this estimate excluded a beneficial effect of 15 percent or more or a harmful effect of 5 percent or more. The data also indicated no statistically significant beneficial or harmful effect of vitamin E on any cataract subtype.
The Women's Health Study was a randomized, double-blind, placebo-controlled trial originally designed to test whether vitamin E supplementation for 10 years decreased the risks of cardiovascular disease and cancer among 39,876 apparently healthy female health professionals in the United States. Because pathogenic mechanisms and risk factors may differ for different types of cataract, the authors also examined whether vitamin E had a differential impact on various cataract subtypes.
The authors conclude that whether long-term treatment with other antioxidant nutrients, or various combinations of nutrients, can be of benefit in delaying cataract onset or progression remains to be determined in other completed and ongoing trials.