Dietary supplements can decrease the advancement of age-related macular degeneration (AMD), the most prevalent cause of blindness in older Americans, according to the Age-Related Eye Disease Studies (AREDS and AREDS2). Scientists reviewed ten years of AREDS2 data in a new report.
They found that the AREDS2 formula, which replaced beta-carotene with antioxidants lutein and zeaxanthin, not only reduces the risk of lung cancer caused by beta-carotene, but also reduces the risk of AMD progression when compared to the original formula. JAMA Ophthalmology published a report on the study, which was financed by the National Institutes of Health.
“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 Emily Chew, M.D., director of the Division of Epidemiology and Clinical Application at the National Eye Institute (NEI), and lead author of the study report. “This 10-year data confirms that not only is the new formula safer, it’s actually better at slowing AMD progression.”
The retina, the light-sensitive tissue at the back of the eye, is affected by AMD, which is a degenerative illness. Blindness results from the death of retinal cells in the macula, the portion of the retina that provides crisp center vision. Although treatment can reduce or reverse visual loss, there is no cure for AMD.
The first AREDS trial, which began in 1996, found 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 considerably reduce the progression of AMD from moderate to late illness. People who smoked and took beta-carotene, on the other hand, had a considerably higher risk of lung cancer than expected, according to two separate studies.
Chew and colleagues compared the beta-carotene formulation to one containing 10 mg lutein and 2 mg zeaxanthin in AREDS2, which began in 2006. Lutein and zeaxanthin, like beta-carotene, are antioxidants that have activity in the retina. Only those who had never smoked or had recently stopped were given the beta-carotene-rich formulation.
The researchers determined that lutein and zeaxanthin did not raise the risk of lung cancer over the five-year AREDS2 study period, and that the novel formulation could reduce the risk of AMD development by roughly 26%. After the five-year trial period was completed, all study participants were given the final AREDS2 formulation, which contained lutein and zeaxanthin instead of beta-carotene.
In this new report, researchers kept in touch with 3,883 of the original 4,203 AREDS2 participants five years after the study ended in 2011.
They wanted to know if their AMD had gotten worse and if they had been diagnosed with lung cancer. Even though everyone in the study switched to the formula with lutein and zeaxanthin when the study was over, the follow-up study showed that beta-carotene nearly doubled the risk of lung cancer for people who had ever smoked. People who took lutein/zeaxanthin didn’t have a higher risk of getting lung cancer.
Also, after 10 years, the group that was originally given lutein/zeaxanthin had a 20 percent lower chance of getting late AMD than the group that was originally given beta-carotene.
“These results confirmed that switching our formula from beta-carotene to lutein and zeaxanthin was the right choice,” said Chew.
The work was funded via the NEI Intramural program (EY000546) and contracts (AREDS2 contract HHS-N-260-2005-00007-C; ADB contract NO1-EY-5-0007; AREDS Contract NOI-EY-0-2127, and contract HHS-N-263-2013-00005-C).
The National Institutes of Health’s Office of Dietary Supplements, National Center for Complementary and Integrative Health, National Institute on Aging, National Heart, Lung, and Blood Institute, and National Institute of Neurological Disorders and Strokes all contributed funds to the AREDS2 contracts. The research was carried out at the National Institutes of Health’s Clinical Center.