Age-Related Eye Disease Study
- investigate the natural history and risk factors of age-related macular degeneration (AMD) and cataracts, and
- 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 (wet macular degeneration) or atrophic age-related macular degeneration (geographic atrophy). 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:
- 500 milligrams of vitamin C;
- 400 international units of vitamin E;
- 15 milligrams of beta-carotene (or 25,000 international units of vitamin A);
- 80 milligrams of the dietary mineral zinc, in the form of zinc oxide; and
- two milligrams of copper as cupric oxide, added to prevent copper deficiency anemia, a condition associated with high levels of zinc intake.
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 (300%) increase in risk of progression.
The study was followed by AREDS2, a five-year study (starting in 2006) 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 (10 mg and 2 mg), omega-3 fatty acids (1,000 mg), 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."
- Age-Related Eye Disease Study Research Group (October 2001). "AREDS Report No. 8: A Randomized, Placebo-Controlled, Clinical Trial of High-Dose Supplementation With Vitamins C and E, Beta Carotene, and Zinc for Age-Related Macular Degeneration and Vision Loss". Archives of Ophthalmology. 119 (10): 1417–1436. doi:10.1001/archopht.119.10.1417.
- The Age-Related Eye Disease Study Research Group (June 2006). "The Age-Related Eye Disease Study (AREDS): Design Implications AREDS Report No. 1". Controlled Clinical Trials. 20 (6): 573–600. doi:10.1016/S0197-2456(99)00031-8. PMC 1473211. PMID 10588299.
- "Response to AREDS supplements according to genetic factors: survival analysis approach using the eye as the unit of analysis". July 2016.
- "CFH and ARMS2 genetic risk determines progression to neovascular age-related macular degeneration after antioxidant and zinc supplementation". January 2018.
- "NIH study provides clarity on supplements for protection against blinding eye disease". May 2013. Archived from the original on 2013-06-07. "Lutein/Zeaxanthin and Omega-3 Fatty Acids for Age-Related Macular Degeneration. The Age-Related Eye Disease Study 2 (AREDS2) Controlled Randomized Clinical Trial". JAMA. May 5, 2013.
- Age-Related Eye Disease Study 2 (AREDS2)
- Omenn, Gilbert S.; et al. (1996). "Effects of a Combination of Beta Carotene and Vitamin A on Lung Cancer and Cardiovascular Disease" (PDF). New England Journal of Medicine. 334 (18): 1150–155. doi:10.1056/NEJM199605023341802. PMID 8602180.