Omega-3 fatty acids and macular degeneration

Fish Oil, Eggs and Omega-3 Fatty Acids

A recent study examined the effect of dietary long-chain omega-3 fatty acids (e.g. those from fish and fish oil) on the progression of age-related macular degeneration (AMD) in individuals already at high risk with symptoms in one or both eyes. The results were presented in terms of quintiles of intake expressed as a percentage of total energy intakes. Since there was a wide range of energy intake this makes it hard to apply the results in a simple fashion as regards recommended intakes based on the data. It was found that in comparison between those in the highest intake quintile and those in the lower four quintiles, there was a 30% decrease in the risk of progressing to advanced AMD. For someone with an energy intake of 1800 cal, the highest quintile for docosahexaenoic acid (DHA) was 120 mg/day and for eicosapentaenoic acid (EPA) it was 88 mg/day, based on 9 cal/g of fatty acid.

These results make one wonder about the benefits if much larger amounts had been consumed by supplementation with fish oil capsules. Individuals taking fish oil for cardiovascular protection typically take 1-2 g of fish oil giving them 400 mg of EPA and 200 mg of DHA per gram of oil. However, the authors point to an ongoing trial that will include supplementation with 350 mg of DHA and 650 mg EPA per day, amounts which clearly represents a big advance over typical amounts obtained just from the diet. This study will also look at supplementation with lutein/zeaxanthin (10mg/2mg day) alone or in combination with the above dose of EPA/DHA. This is a 4000 person, 5-year randomized clinical trial and also involves individuals at high risk of AMD. The study was started in late 2006. Readers are referred to the December 2009-January 2010 issue of International Health News for a discussion of a study that used eggs to enhance the intake of retinal pigments in the context of preventing AMD. Eggs are rich in lutein and zeaxanthin. Incidentally, so- called omega-3 eggs typically contain about 400 mg of omega-3 fatty acids per egg but this includes the short chain omega-3 fatty acids which are inefficiently converted to the long-chain acid in human biochemistry.
Sangiovanni JP, Agron E, Meleth AD et al. {omega}-3 Long-chain polyunsaturated fatty acid intake and 12-y incidence of neovascular age-related macular degeneration and central geographic atrophy: AREDS report 30, a prospective cohort study from the Age-Related Eye Disease Study. Am J Clin Nutr 2009 December;90(6):1601-7.

For physicians: Ophthalmology continuing medical education courses covering macular degeneration, vision loss and blindness.

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