Selenium and vitamin E supplementation are unlikely to affect age-related cataract development in older men, according to an article published online September 18 in JAMA Ophthalmology.
William G. Christen, ScD, from the Division of Preventive Medicine and the Division of Medicine at Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, and colleagues conducted an ancillary study within the Selenium and Vitamin E Cancer Prevention Trial (SELECT) Eye Endpoints (SEE) Study.
The SELECT was a 4-group, phase 3, randomized placebo-controlled trial of selenium, vitamin E, and a combination of selenium and vitamin E for the prevention of prostate cancer in 35,533 men, beginning in 2001. The SEE trial involved a subset of 11,267 men, beginning in 2003, excluding men with a prior diagnosis of cataract at baseline.
Participants had a median age of 61 years, with most (64%) ranging in age from 55 to 64 years; 81% were white and 19% were nonwhite; 52% had graduated from college; 43% were never-smokers, 48% were former smokers, and 9% were current smokers; and 62% had 1 or more alcohol drinks a month and 33% rarely or never drank alcohol.
Researchers randomly assigned the SEE participants to receive vitamin E (n = 2844), selenium and vitamin E (n = 2789), selenium (n = 2805), or placebo (n = 2829). They then compared cataract incidence among the selenium vs no-selenium groups and the vitamin E vs no–vitamin E groups.
During 5.6 years of follow-up, 185 cataracts developed in the selenium groups and 204 in the no-selenium group, for a nonsignificant reduction of 9% for the selenium groups. For cataract extractions, 99 cases occurred in the selenium groups and 120 in the no-selenium groups, for a nonsignificant reduction of 16%.
In addition, 197 cataracts developed in the vitamin E groups and 192 in the no–vitamin E groups. Cataract extractions occurred in 114 vitamin E cases and in 105 no–vitamin E cases, with both hazard ratios hovering around the null value of 1.0.
First for Selenium
"To our knowledge, the SEE study is the first randomized trial to assess the separate effect of selenium supplementation in cataract prevention," the researchers write.
"Our null findings for vitamin E in cataract prevention are consistent with the overall negative findings in previous randomized trials and, in particular, with 4 trials designed to estimate the individual effect of vitamin E supplementation."
They conclude, "These randomized trial data from a large cohort of apparently healthy men indicate that long-term daily supplemental use of vitamin E has no material impact on cataract incidence. The data also exclude any large beneficial effect on cataract for long term supplemental use of selenium, with or without vitamin E, although a smaller but potentially important beneficial effect could not be ruled out."
"It is difficult to do a study like this because there are so many variables, and it's really hard to control for dietary factors and to actually get accurate reports," Shuchi Patel, MD, assistant professor of ophthalmology at Loyola Stritch School of Medicine in Maywood, Illinois, told Medscape Medical News.
However, she added, "With this many people enrolled and to have follow-up for so long makes it a unique and probably a very reliable study."
However, it probably will not change clinical practices, because prescribing vitamin E and selenium for cataract "is definitely not mainstream," she said. "We definitely advise [vitamins] and prescribe for other eye conditions, particularly macular degeneration, either multivitamins or specifically vitamins. And I don't think this study indicates that there is any worsening of [cataracts]. It's just that the benefit of it is not as clear for cataracts as it is for improving macular degeneration."
The limitation of the study she characterized is that the researchers did not distinguish among cataracts. "It's hard to categorize what you're calling a cataract. The degree, the kind of cataract, the severity of the cataract, and having so many different ophthalmologists screening them, makes it a little difficult to say what this really [means]," she noted, especially regarding cataract surgery.
She continued, "I might take out a cataract at 20-60, and other people might take one out at 20-30. The severity of the cataract wasn't graded, and they may have found something a little more significant if they were looking at the severity of the cataract. Otherwise, I thought it was a really well-done study."
This research was supported by the National Institutes of Health and the National Center for Complementary and Alternative Medicine. One coauthor has reported receiving support and a speaking honorarium from Pfizer related to vitamins. The other authors and Dr. Patel have disclosed no relevant financial relationships.
JAMA Ophthalmol. Published online September 18, 2014. Abstract
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Cite this: Vitamin E, Selenium: No Effect on Cataract Risk in Men - Medscape - Sep 19, 2014.