The Age-Related Eye Disease Studies (AREDS and AREDS2) established that dietary supplements can slow progression of age-related macular degeneration (AMD), the most common cause of blindness in older North Americans.
In a new report, scientists analyzed 10 years of AREDS2 data. They found that the AREDS2 formula, which substituted the antioxidants lutein + zeaxanthin for beta-carotene, not only reduced risk of lung cancer due to beta-carotene, but was also more effective at reducing risk of AMD progression, compared to the original formula.
"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 the 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."
About age-related macular degeneration
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, there is no cure for AMD.
Original AREDS findings
The original AREDS study, launched in 1996, showed that a supplement containing 500 mg vitamin C, 400 IU 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 supplements had a significantly higher risk of lung cancer than expected.
The latest research
In AREDS2, which began in 2006, the researchers compared the beta-carotene formulation to one with 10 mg lutein and 2 mg zeaxanthin instead. Like beta-carotene, lutein and zeaxanthin belong to the carotenoid family and have antioxidant activity in the retina.
The beta-carotene-containing formation was only given to participants who had never smoked or who had quit smoking.
At the end of the five-year AREDS2 study period, the researchers concluded that lutein and zeaxanthin did not increase risk for lung cancer, and that the new formation could reduce the risk of AMD progression by about 26%.
After the completion of the five-year study period, the study participants were all offered the final AREDS2 formation that included lutein and zeaxanthin instead of beta-carotene.
Source: JAMA Ophthalmology, June 2, 2022.
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