Findings from this multicenter, NEI and NIH sponsored study were reported in the October 2001 issue of Archives of Ophthalmology. The study followed 3,640 participants, aged 55-80, for an average of 6.3 years. Patients were initially enrolled in four AMD categories based on the size and extent of retinal drusen and level of visual acuity decline (Table 1), and were randomly assigned to one of four treatment arms:

• Antioxidants plus zinc (500 mg vitamin C, 400 IU vitamin E, 15 mg beta-carotene, 80 mg zinc)
• Antioxidants alone
• Zinc alone
• Placebo

While the investigators acknowledged the importance of lutein and zeaxanthin for macular health, these carotenoids were not available for use in supplements when the study began. Instead, the investigators chose beta-carotene, which was then being studied for heart disease and cancer.

Although the antioxidant and zinc supplements each appeared to offer some protection, the benefits of supplementation were greatest for those patients who received the antioxidant and zinc combination, and who were in the highest-risk category groups.

Supplementation with combined antioxidants and zinc significantly reduced the risk of progression to advanced AMD in these groups by 25%. A significant risk reduction in vision loss was also seen in the higher-risk groups taking both zinc and antioxidants, with an odds reduction of 27% (Table 2).

Very few patients with less severe AMD went on to develop advanced cases. Therefore the study was unable to detect whether the zinc and antioxidant combination might delay or prevent progression in subjects at an earlier stage. However, when the researchers included the less severe category (category 2) with the more advanced categories (3 and 4), the combined supplements showed an odds reduction in the visual acuity outcome that approached statistical significance (Table 2).

Most of the participants experienced few side effects. People in the zinc groups had more frequent urinary-tract related problems than placebo-takers (7.5% vs. 5%), although it's not clear whether zinc played a role in their occurrence. Another caveat is that high dose beta-carotene is contra-indicated for smokers and recent ex-smokers. The AREDS trial confirmed the general safety and benefit of these high-potency nutrients in preserving vision among well-nourished, older people with intermediate to more advanced AMD.

Click here to read the full text of the AREDS clinical trial on the Archives of Opthalmology website.

Reference

1. Age-Related Eye Disease Study Research Group. 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. Arch Ophthalmol 119:1417-36, 2001.