evaluate the effects of high doses of antioxidants and zinc on the progression of the two conditions in those with AMD.
The study followed 3640 individuals for an average of 6.3 years between 1992 and 2001. The researchers concluded that high levels of antioxidants and zinc can reduce some people's risk of developing advanced AMD by about 25 percent. Advanced AMD is defined as either choroidal neovascularization or atrophic age-related macular degeneration. The anti-oxidants and zinc supplements only reduced the risk of progression to wet macular degeneration. Those that benefited from the dietary supplements included those with intermediate-stage AMD and those with advanced AMD in one eye only. The supplements had no significant effect on the development or progression of cataracts. "High levels" in this case were defined to be:
The results were reported in the October 2001 issue of Archives of Ophthalmology. Bausch & Lomb was a collaborator in the study. They and other suppliers, provide supplements pre-packaged with formulations based on this study. Studies in 2016 and 2018 have now shown that this average 25 percent reduction in risk from the combination of anti-oxidants and zinc varies by genotype. Some patients have as much as an 85% reduction in progression risk, while others see a 3 fold increase in risk of progression.
AREDS2
The study was followed by AREDS2, a five-year study designed to test whether the original AREDS formulation would be improved by adding omega-3 fatty acids; adding lutein and zeaxanthin; removing beta-carotene; or reducing zinc. In AREDS2, participants took one of four AREDS formulations: the original AREDS formulation, AREDS formulation with no beta-carotene, AREDS with low zinc, AREDS with no beta-carotene and low zinc. In addition, they took one of four additional supplement or combinations including lutein and zeaxanthin, omega-3 fatty acids, lutein/zeaxanthin and omega-3 fatty acids, or placebo. The study reported that there was no overall additional benefit from adding omega-3 fatty acids or lutein and zeaxanthin to the formulation. However, the study did find benefits in two subgroups of participants: those not given beta-carotene, and those who had very little lutein and zeaxanthin in their diets. Removing beta-carotene did not curb the formulation's protective effect against developing advanced AMD, which is important given that high doses of beta-carotene have been linked to higher risk of lung cancers in smokers. According to Dr. Emily Chew, "Because carotenoids can compete with each other for absorption in the body, beta-carotene may have masked the effect of the lutein and zeaxanthin in the overall analysis."
