Greater Omega-3 fatty acid intake associated with protection against advanced age-related macular degeneration

by Wilmer Eye Institute

Researchers from Wilmer Eye Institute at Johns Hopkins University report in the December, 2010 issue of the journal Ophthalmology the finding of a protective effect for fish that contain abundant amounts of the omega-3 fatty acids EPA and DHA against the development of advanced age-related macular degeneration (AMD). The disease is the leading cause of blindness among older Americans of European descent and the number of individuals with advanced AMD is expected to rise by 50% by the next decade.

For their analysis, Sheila K. West, PhD and her associates evaluated data from 2,391 participants in the Salisbury Eye Evaluation (SEE) Study, which included men and women between the ages of 65 and 84 residing in Maryland. Dietary questionnaire responses were analyzed for the type and amount of fish and shellfish consumed weekly. Fundus photographs taken upon enrollment were evaluated for the presence and grade of macular degeneration.

Two hundred twenty-seven subjects were found to have early macular degeneration. One hundred fifty-three had intermediate-stage disease, and advanced macular degeneration, classified as the presence of abnormal blood vessel growth and bleeding or geographic atrophy, was observed in 68 participants. Although there did not appear to be a significant protective effect for fish and shellfish in general, those whose intake of high omega-3 fatty acid fish was greatest at one or more servings per week had a 60 percent lower risk of advanced disease compared to those who consumed less than one serving.

The finding adds evidence to that of other research, including the Age-Related Eye Disease Study (AREDS), concerning the benefit of nutritional components against macular degeneration. High amounts of omega-3s have been measured in the retina of the eye, and may be essential to eye health. Although AREDS found a protective effect for zinc against age-related macular degeneration, the current study failed to associate greater intake of seafood containing a high amount of the mineral with a lower risk of AMD; however, the authors note that dietary levels of zinc, which average 13 milligrams per week in diets that include crab and oysters, are significantly lower than the 80 milligrams per day of supplemental zinc that was administered in the trial.

"Our study corroborates earlier findings that eating omega-3-rich fish and shellfish may protect against advanced AMD," Dr West stated. "While participants in all groups, including controls, averaged at least one serving of fish or shellfish per week, those who had advanced AMD were significantly less likely to consume high omega-3 fish and seafood."

"Future studies, as suggested by a recent systematic review, are needed to further elucidate the association between the consumption of fish, shellfish, zinc, and omega-3 fatty acids and the risk of AMD," the authors recommend.