Eye health claims made for some supplements are not supported by evidence, and the supplements could pose a risk to the user, researchers say.
"The scary thing is that the [US Food and Drug Administration] doesn't regulate these supplements for safety or efficacy," Jennifer J. Yong, MD, told Medscape Medical News.
Dr Yong, a resident at Yale-New Haven Hospital-Waterbury Hospital in Waterbury, Connecticut, and colleagues published a study examining supplement contents online November 20 in Ophthalmology.
Specific Formulas Are Proven
The Age-Related Eye Disease Study (AREDS), a randomized controlled trial published in 2001, showed that a specific formula of nutrients reduced the risk for vision loss from age-related macular degeneration in the intermediate and advanced stages of the disease.
The AREDS formula, made up of high doses of vitamin C, vitamin E, beta-carotene, and zinc, is patented by Bausch and Lomb.
It did not show any benefits in patients with cataracts, patients without eye disease, or even patients in the early stages of macular degeneration.
Because other studies have linked beta-carotene to lung cancer in smokers, researcher tried a second AREDS formula, known as AREDS2, in which lutein and zeaxanthin take the place of beta carotene. They showed it to be safe and effective in the same way as the original formula.
Not All Supplements Equal
Many adults use supplements for eye health, the researchers report. "Among the 59% of adults in the United States who take dietary supplements, 7% use a supplement for eye health," they write, citing a Multi-Sponsor Surveys Inc 2011 study of US Eye Health.
To find out what sort of supplements these people might be taking, the researchers examined labels from 11 supplement products from the leading five brands, as defined by dollar sales from June 2011 to June 2012, tracked by SymphonyIRI.
Of the supplements examined, only four (36%) contained the same ingredients in the same doses used in the AREDS and AREDS2 studies.
Three of these were marketed by Bausch & Lomb: PreserVision Eye Vitamin AREDS Formula Tablets, PreserVision Eye Vitamin AREDS Formula Soft Gels, and PreserVision AREDS2 Formula. The fourth, ICAPS Eye Vitamin AREDS Formula, is made by Alcon Laboratories under license from Bausch & Lomb.
Yet when the researchers looked at the consumer websites for the 11 supplements examined, they found that six (55%) contained information about AREDS. In addition, all of the product websites stated that supplements promote eye health.
Of the remaining seven products that differed from AREDS, some contained the AREDS vitamins, but in different doses. Others contained the AREDS vitamins, and other vitamins as well. Only two of the websites the researchers analyzed specified that the supplements would only benefit patients in the intermediate and advanced stages of age-related macular degeneration.
Patients who misuse supplements may put themselves at unnecessary risk, the researchers write. Genitourinary hospitalizations have been associated with the AREDS formula, they note. Beta-carotene may increase the risk for lung cancer in smokers, and the daily dose of vitamins in AREDS may increase the risk for prostate cancer in men with high baseline levels of selenium.
Confusing for Patients
The new data call attention to a problem well-known among retina specialists, Rahul Khurana, MD, a clinical spokesperson for the American Academy of Ophthalmology, told Medscape Medical News. "It's very confusing for our seniors," he said.
In addition to the risk for adverse effects, the vitamins are an unnecessary expense for many people who cannot afford them, he said. Moreover, people are more likely to make an error in taking their medications when they have a larger number to manage.
"I see people every day with macular degeneration, and I see their families," said Dr Khurana, a clinical assistant professor of ophthalmology at the University of California, San Francisco.
"They are worried, and they want to take these vitamins prophylactically, but there is no evidence of a benefit from taking these vitamins prophylactically. I tell them avoiding smoking, having a diet rich in dark green vegetables, those are things that are not only good for your eyes but good for your health in general."
John Pollack, MD, a spokesperson for the American Society of Retina Specialists, recommends providing patients with a list of ingredients and doses for the AREDS formula in writing. Oral instructions are too hard to remember, he told Medscape Medical News.
"The problem is, when they go to the grocery store they are faced with a dizzying array of supplements, and no matter what you tell them, they forget it," said Dr Pollack, an assistant professor of ophthalmology at Rush University Medical Center in Chicago, Illinois.
The authors and Dr Khurana have disclosed no relevant financial relationships. Dr Pollack has invested in Covalent Medical, which makes supplements marketed for eye health.
Ophthalmology. Published online November 20, 2014. Abstract
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Cite this: Macular Degeneration: Not All Supplements Equal, Experts Warn - Medscape - Dec 08, 2014.