Null Findings on Selenium Supplements for Cataract Prevention

SEPTEMBER 19, 2014
Jeannette Y. Wick, RPh, MBA, FASCP
Selenium supplementation has been studied as a potential prophylactic measure for thyroid disease and various types of cancer, but its role in cataract prevention is of particular interest to researchers, considering the eye’s lens is rich in vitamin E and selenium.

However, the results of trials on vitamin E have been disappointing, and now, a new study that appears online in JAMA Ophthalmology has suggested that selenium and vitamin E supplementation will not prevent cataracts.

For the study, an international team of researchers relied on data from the large randomized placebo controlled Selenium and Vitamin E Cancer Prevention Trial (SELECT) that enrolled 35,533 men. The ancillary Eye Endpoints Study was structured to detect correlations between selenium and vitamin E intake and cataract formation in 11,267 men aged 50 years or older, for those who were black, and 55 years and older, for all other ethnicities.

The SELECT study had 4 arms: selenium 200 mcg/day alone, vitamin E 400 IU/day alone, selenium with vitamin E, and placebo. It is important to note that the interim review panel terminated the trial early due to lack of efficacy in prostate cancer, possible adverse events that included small increases in type 2 diabetes mellitus in the selenium-only arm, and increased risk of prostate cancer in the vitamin E-only group.

Nonetheless, the participants were treated and followed for an average of 5.6 years. Among them, the researchers found 389 cataract cases. Although cataract development was similar across all study arms, there was a nonsignificant trend for fewer cataract formations in the selenium-treated arms.

Still, this study, which was the first randomized placebo controlled investigation of selenium in apparently healthy men, indicated that selenium’s role in cataract formation, if any, is small. Three previous trials failed to determine selenium’s role in cataract prevention.