Age-related macular degeneration (AMD), is a major cause of central vision loss in the elderly. Treatments are limited and hope lies in reducing the risk of the disease and preventing its development. A study reported at the Annual Meeting of the Association for Research in Vision and Ophthalmology, in Florida, May, 2003, provides new data supporting the effects of diet and nutrients, in lowering the risks of having a type of AMD that leads to blurred vision, and in severe cases, blindness. The study, carried out by Dr. JP SanGiovanni and colleagues, from the National Eye Institute, in Bethesda MD, showed, that after taking into account other nutrient and non- nutrient factors, that may affect the risk of AMD, a higher intake of omega n-3 polyunsaturated fatty acids (LCPUFA) and fish was associated with decreased risk of having neovascular AMD.
Approximately 1.7 million people over 64, suffer from the severe form AMD, that leads to blindness. The macula is an area located in the center of the retina and is responsible for fine and detailed central vision. The degenerative changes associated with AMD include alterations in the retinal tissues and atrophy of the cells, that account for a number of different types of AMD, and the formation of new blood vessels (neovacularization) under the retina, that accounts for another type, called neovascular AMD, where leaking blood vessels distort the retina and cause blurred vision and loss of eyesight.
The Age-Related Eye Disease Study (AREDS), reported at the meeting, was a case control retrospective study of 4,513 participants, aged 60 to 80 years. Subjects completed a self-administered food questionnaire, and provided information on the frequency and portions of fish intake in the last year, as well as other health and lifestyle data. The types of fish considered, included fried fish or fish sandwiches, tuna salad or tuna casserole, oysters, other shell fish and broiled or baked fish. People without AMD served as control groups for each of the four different types of AMD tested.
The results showed that highest total fish consumption (compared to no intake), of more than two servings a week, of broiled or baked fish or of tuna, reduced the risk of having neovascular AMD, but not other types of AMD, by approximately 50%.
When assessing AMD risk in relation to intake of omega-3 fatty acids, that are high in marine products, the results showed that risk for neovascular AMD, but not other types of AMD, was significantly decreased, by approximately 60%, for people with the highest intake of total omega-3 fatty acids (highest quintiles versus lowest quintiles). A similar risk reduction (approximately 53%), was found with intake of docosahexaenoic (DHA), an omega-3 fatty acid, that is selectively taken up and retained in the photoreceptors of the eye.
The studies indicate an independent association between fish intake and omega-3 fatty acids intake and neovascular AMD, showing that high intake of fish, or omega-3 fatty acids, halves the risk of having the disease.
—Carmia Borek, Ph.D.