Sunlight, toxic environmental processes, and even normal metabolic activities can generate highly reactive molecules known as free radicals. These free radicals can damage surrounding cells and tissues. Antioxidant vitamins and minerals protect against injury caused by free radicals. There are over 200 antioxidants, including vitamins A, C, and E; beta-carotene; and minerals such as selenium and zinc.
Free radical formation has been implicated in a number of conditions, including cataracts, dry eye, and macular degeneration. The retina seems to be more susceptible to this damage than other tissues. Some studies suggest that the intake of antioxidant vitamins may help to delay the formation or slow the progress of these conditions. These relationships were extensively studied in a major multicenter clinical trial known as the Age-Related Eye Disease Study (AREDS). It was sponsored by the National Eye Institute, one of the federal government's National Institutes of Health. The AREDS set out to determine the natural history and risk factors of age-related macular degeneration (AMD) and cataract and to evaluate the effect of high doses of antioxi-dants and zinc on the progression of AMD and cataract.
Results from the AREDS showed that high levels of antioxidants and zinc significantly reduce the risk of advanced age-related macular degeneration (AMD) and its associated vision loss. These same nutrients had no significant effect on the development or progression of cataract.
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