Antioxidants linked to reduced risk of age-related macular degeneration
Age-related macular degeneration (AMD) is a degenerative disorder of the macula, the central part of the retina, and is the most common cause of irreversible blindness in developed countries, according to background information in the article.
29/12/05 A diet with a high intake of beta carotene, vitamins C and E, and zinc is associated with a substantially reduced risk of age-related macular degeneration in elderly persons, according to a study in the December 28 issue of JAMA.
Age-related macular degeneration (AMD) is a degenerative disorder of the macula, the central part of the retina, and is the most common cause of irreversible blindness in developed countries, according to background information in the article. Late-stage AMD results in an inability to read, recognize faces, drive, or move freely. The prevalence of late AMD steeply increases with age, affecting 11.5 percent of white persons older than 80 years. In the absence of effective treatment for AMD, the number of patients severely disabled by late-stage AMD is expected to increase in the next 20 years by more than 50 percent to 3 million in the United States alone. Epidemiological studies evaluating both dietary intake and serum levels of antioxidant vitamins and AMD have provided conflicting results. One study (called AREDS) showed that supplements containing 5 to 13 times the recommended daily allowance of beta carotene, vitamins C and E, and zinc given to participants with early or single eye late AMD resulted in a 25 percent reduction in the 5-year progression to late AMD.
Redmer van Leeuwen, M.D., Ph.D., of Erasmus Medical Centre, Rotterdam, the Netherlands, and colleagues investigated whether antioxidants, as present in normal daily foods, play a role in the primary prevention of AMD. Dietary intake was assessed at baseline in the Rotterdam Study (1990-1993) using a semiquantitative food frequency questionnaire. Follow-up continued through 2004. The Rotterdam Study included inhabitants aged 55 years or older from a middle-class suburb of Rotterdam, the Netherlands. Of 5,836 persons at risk of AMD at baseline, 4,765 had reliable dietary data and 4,170 participated in the follow-up.
Average follow-up of participants was 8.0 years. During this period, 560 persons (13.4 percent) were diagnosed as having new AMD, the majority of whom had early-stage AMD. A significant inverse association was observed for intake of vitamin E, iron, and zinc. After adjustment, a 1-standard deviation increase in intake was associated with a reduced risk of AMD of 8 percent for vitamin E and 9 percent for zinc. An above-median (midpoint) intake of beta carotene, vitamins C and E, and zinc, compared with a below-median intake of at least 1 of these nutrients, was associated with a 35 percent reduced risk of AMD, adjusted for all potential confounders. In persons with a below-median intake of all 4 nutrients, the risk of AMD was increased by 20 percent. Adding nutritional supplement users to the highest quartile of dietary intake did not change the results.
