NIH Study Confirms Benefit of Supplements for Slowing Age-Related Macular Degeneration
WASHINGTON — A pair of National Institutes of Health studies on age-related eye disease have established that dietary supplements can slow progression of age-related macular degeneration, the most common cause of blindness in older Americans.
In a recent report, scientists analyzed 10 years of data from the NIH’s Age-Related Eye Disease Studies and found that the so-called AREDS2 formula, which substituted antioxidants lutein and zeaxanthin for beta carotene, not only reduces risk of lung cancer due to beta carotene, but is also more effective at reducing risk of AMD progression, compared to the original formula that the study had considered.
A report on the study, funded by the NIH, was published in JAMA Ophthalmology in June.
“Because beta carotene increased the risk of lung cancer for current smokers in two NIH-supported studies, our goal with AREDS2 was to create an equally effective supplement formula that could be used by anyone, whether or not they smoke,” said Dr. Emily Chew, director of the Division of Epidemiology and Clinical Application at the National Eye Institute, in a written statement.
Chew, who is also lead author of the study report, went on to say the 10-year data “confirms that not only is the new formula safer, it’s actually better at slowing AMD progression.”
AMD is a degenerative disease of the retina, the light-sensitive tissue at the back of the eye. Progressive death of retinal cells in the macula, the part of the retina that provides clear central vision, eventually leads to blindness. Treatment can slow or reverse vision loss; however, no cure for AMD exists.
The original AREDS study, launched in 1996, showed that a dietary supplement formulation (500 mg vitamin C, 400 international units vitamin E, 2 mg copper, 80 mg zinc, and 15 mg beta carotene) could significantly slow the progression of AMD from moderate to late disease.
However, two concurrent studies also revealed that people who smoked and took beta carotene had a significantly higher risk of lung cancer than expected.
In AREDS2, begun in 2006, Chew and colleagues compared the beta carotene formulation to one with 10 mg lutein and 2 mg zeaxanthin instead. Like beta carotene, lutein and zeaxanthin are antioxidants with activity in the retina. The beta carotene–containing formulation was only given to participants who had never smoked or who had quit smoking.
In this new report, the researchers followed up with 3,883 of the original 4,203 AREDS2 participants an additional five years from the end of the AREDS2 study in 2011, collecting information on whether their AMD had progressed to late disease and whether they had been diagnosed with lung cancer.
Even though all the participants had switched to the formula containing lutein and zeaxanthin after the end of the study period, the follow-up study continued to show that beta carotene increased risk of lung cancer for people who had ever smoked by nearly double.
There was no increased risk for lung cancer in those receiving lutein/zeaxanthin. In addition, after 10 years, the group originally assigned to receive lutein/zeaxanthin had an additional 20% reduced risk of progression to late AMD compared to those originally assigned to receive beta carotene.