Several recent studies suggest that antioxidant vitamins may play a role in reducing the risk and progression of age-related macular degeneration and cataracts, the two leading age-related eye diseases. The research was presented at the annual meeting of the American Academy of Ophthalmology (AAO) in a session entitled “Vitamin and Mineral Supplements and Eye Disease.”
According to researchers at the National Eye Institute (NEI), high levels of antioxidant vitamins and zinc significantly reduce the risk of developing advanced age-related macular degeneration (AMD) and its associated vision loss. AMD is a serious and currently untreatable disease that is the number one cause of vision impairment and acquired blindness among aging Americans.
In the Age-Related Eye Disease Study (AREDS), a seven-year intervention trial investigating the role of antioxidant vitamins in the risk reduction for AMD and cataracts, people at high risk of developing advanced stages of AMD lowered their risk by about 25% when taking a combination of the antioxidant vitamins E and C, beta-carotene and zinc.
“Treatment for advanced AMD is quite limited. These supplements will delay progression to advanced AMD in about 300,000 people who are at high risk,” said Johanna M. Seddon, MD, director of the Epidemiology Unit at the Massachusetts Eye and Ear Infirmary (MEEI) and lead investigator of the AREDS study at MEEI, one of the 11 participating clinical centers.
The participants were administered the following doses during testing:
500 milligrams of vitamin C
400 IU of vitamin E
15 milligrams of beta-carotene
80 milligrams of zinc
2 milligrams of copper (to prevent anemia from high dose zinc)
“The high levels of nutrients that were evaluated in the AREDS are very difficult to achieve from diet alone. This discovery is very exciting because these dietary supplements are the first effective treatment to slow the progression of the disease in people at high risk for developing advanced AMD,” added Dr. Seddon.
In the cataract arm of the AREDS, researchers found that the supplements did not provide an apparent benefit in preventing or delaying the progression of cataracts. However, two other new studies suggest antioxidant vitamins may play a role in reducing the risk of cataracts, as well as the progression of existing cataracts.
Cataracts, which affect more than half of all Americans aged 65 and older, are the clouding of the lens that can ultimately result in blindness. It has been theorized that among other factors, oxidative damage contributes to the development of cataracts.
Antioxidants have been found to neutralize the free radicals that cause oxidative damage. Roche European American Cataract Trial The Roche European American Cataract Trial (REACT) found that supplements containing vitamins C and E slowed the progression of cataracts. Participants in this study were given a supplement containing 750 mg of vitamin C, 600 IU of vitamin E and 18 mg of beta-carotene daily for three years.
The second study, the Nutrition and Vision Project, examined the occurrence of cataracts in a group of women participating in the Nurses’ Health Study. This study, led by Allen Taylor, Ph.D., and director of the Laboratory for Nutrition and Vision Research at Tufts University, consisted of three analyses of specific nutrients and their roles in cataract prevention.
The first analysis found that individuals with the highest intake of the antioxidant vitamin C had significantly lower rates of nuclear cataracts, the most common form of cataracts, which are found in the center or “nuclear” area of the lens. In the second analysis, higher intakes of vitamin C lowered the risk of cortical cataracts in women less than 60 years of age.
Cortical cataracts are less common than nuclear cataracts and are found in the outer region of the lens. The results of this analysis will be published in the January 2002 issue of the American Journal of Clinical Nutrition.
The third analysis, a five-year follow-up of the Nutrition and Vision Project, showed that use of vitamin E supplements for more than 10 years was associated with a decreased progression of nuclear cataracts. Subjects who took vitamin E supplements for more than ten years had 29% less cataract progression than subjects who did not take supplements.