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Omega-3 Fats May Help Macular Degeneration

Abstracted by Marcia J. Egles, MD, December 4, 2009 from 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 by John Paul SanGiovanni et al in The American Journal of Clinical Nutrition 90:1601-1607, Dec. 2009.

Affecting an estimated 1.75 million Americans, age-related macular degeneration (AMD) is a major and increasing cause of irreversible visual loss (1). A 12-year multicenter study (2) from the United States’ National Institute of Health (NIH) identified omega-3 fatty acids in the diet as a possible means to help prevent AMD.

The macula is a specialized part of the eye’s retina, which allows a person to see sharp detail in the center of the visual field.  Degeneration of this crucial structure is associated with advanced age.  More than 30% of those over age 75 have visual loss from AMD.  Cigarette smokers take on twice the risk of developing AMD, compared to non-smokers (3). An NIH clinical trial reported that B vitamins may be of help in protecting against AMD (4).  Antioxidants such as vitamins C and E, beta carotene and zinc may slow the progression of AMD (5).

Omega-3 long-chain polyunsaturated fatty acids, which include docasahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), are thought to be involved in altering the inflammatory changes that are part of macular degeneration (6,7,8). The newly reported NIH study concerning omega-3 fatty acids is part of the Age Related Eye Disease Study (AREDS).  From 1992-1998, 1837 male and female patients aged 55-80 were enrolled in the study.  In general, the participants were under care for macular degeneration, but had one less affected eye with good vision. The “good eye” was followed in this study and observed for progression to more advanced degeneration.  The diets of the participants were assessed through food frequency questionnaires done at the start of the study. The patients were followed until 2005.

The study found that those with the highest consumption of omega-3 fatty acids had the best outcomes for macular degeneration.  Those with the highest consumption, with omega-3 fatty acids accounting for 0.11% of their total calories (this is about 360 mg for a 3000-calorie intake), were 30% less likely than their peers (who consumed 0.01%) to advance to more serious forms of macular degeneration.  The major sources of omega-3 fatty acids in the participants’ diets were fish and seafood.

This study is an observational study of substantial size and duration.  The results require confirmation by further studies and clinical trial.   Currently ongoing is AREDS-2, a clinical trial, which should be completed by 2013.  Part of AREDS-2 will test treatment of macular degeneration with omega-3 fatty acid supplementation (9).

REFERENCES

1.  Friedman, DS, O'Colmain, BJ, Muñoz, B, et al. Prevalence of age-related macular degeneration in the United States. Arch Ophthalmol 2004;122:564–72.
2.  John Paul San Giovanni 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. American Journal of Clinical Nutrition 90:1601-1607, Dec. 2009.
3.  Christen WG, et al.  A prospective study of cigarette smoking and risk of age-related macular degeneration in men. JAMA.1996;276 (14):1147-1151.
4.  Christen,WG et al.  Folic Acid,Pyridoxine, and Cyanocobalamin Combination Treatment and Age-Related Macular Degeneration in Women.  Arch Internal Medicine, Feb 23,2009: 169 (4) p. 335-342.
5.  Age-Related Eye Disease Study Group. A randomized, placebo-controlled clinical trial of high-dose supplementation with vitamins C and E, beta carotene, and zinc for age-related macular degeneration and vision loss: AREDS report no. 8. Arch Ophthalmol 2001;119:1417–36.
6.  Donoso, LA, Kim, D, Frost, A, Callahan, A & Hageman, G. The role of inflammation in the pathogenesis of age-related macular degeneration. Surv Ophthalmol 2006;51:137–52.
7.  SanGiovanni, JP & Chew, EY. The role of omega-3 long-chain polyunsaturated fatty acids in health and disease of the retina. Prog Retin Eye Res 2005;24:87–138.
8.  Seddon, JM, Cote, J & Rosner, B. Progression of age-related macular degeneration: association with dietary fat, transunsaturated fat, nuts, and fish intake. Arch Ophthalmol 2003;121:1728–37.
9.  www.areds2.org