In the United States an estimated 20.5 million people over the age of 40 show some evidence of age-related cataract. For 50% of these individuals, the cataracts are significant enough to impair vision. Cataract surgery is common and readily available, however, the procedure accounts for a large portion of Medicare expenditures. Prevention of cataract is a preferred strategy, yet other than avoidance of cigarette smoking, no other preventative agent has been identified.

Nutrition is suspected to play an important role in cataract development. Since oxidative damage is a feature in cataract, nutritional research has centered on antioxidants, particularly vitamins C and E, and the risk of cataract. A clinical trial, featured in the November 2010 issue of Archives of Ophthalmology, examined the effect of these vitamins on the development of cataract. The trial included 11,545 apparently healthy US male physicians 50 years or older without prior diagnosis of cataracts. The participants were divided into two groups. One group was randomly assigned to receive 400 IU of vitamin E or a placebo on alternate days while the other group was randomly assigned to receive 500mg of vitamin C or a placebo daily.

After 8 years of treatment and follow-up, 1,174 cataracts were confirmed in the vitamin E group. Of these, 579 cataracts were found in the participants receiving vitamin E while 595 participants receiving the vitamin E placebo were found to have cataracts. Similarly, 593 cataracts were found in the group treated with vitamin C while 581 cataracts were found in the vitamin C placebo group.

The clinical trial concluded that long term, alternate day use of 400 IU of vitamin E and daily use of 500 mg of vitamin C had no notable beneficial or harmful effect on the risk of cataract development. Ultimately, long-term use of these two vitamin supplements has no appreciable effect on cataract.