Dietary Omega-3 Fatty Acids May Reduce Risk of Age-Related Macular Degeneration

Laurie Barclay, MD

May 06, 2003

May 6, 2003 — Dietary omega-3 fatty acids but not beta-carotene supplementation is associated with a reduced risk of age-related macular degeneration (AMD), according to two presentations May 4-6 at the Association for Research in Vision and Ophthalmology annual meeting in Fort Lauderdale, Florida. A third presentation suggests that omega-3 fatty acids may also reduce the risk of dry eye syndrome in women.

"Higher intake of omega n-3 long-chain polyunsaturated fatty acid (LCPUFA) and fish was associated with decreased risk of having neovascular AMD after adjusting for nutrient- and nonnutrient-based predictors and correlates of AMD," write J. P. SanGiovanni, from the National Eye Institute in Bethesda, Maryland, and colleagues.

The Age-Related Eye Disease Study (AREDS) was a case-control study of 4,513 participants aged 60 to 80 years at enrollment. Best-corrected visual acuity was 20/32 or better in at least one eye in all subjects.

Compared with the lowest quintile of total n-3 LCPUFA intake, the risk for neovascular AMD was significantly decreased for the highest quintile (odds ratio [OR], 0.60; 95% confidence interval [CI], 0.40 - 0.88), after statistical adjustment for all nutrient- and nonnutrient-based variables. Docosahexaenoic acid, an n-3 LCPUFA that is selectively accreted and retained in the photoreceptor outer segments, also had a protective effect (OR for highest vs. lowest quintile, 0.53; 95% CI, 0.35 - 0.79).

Total fish consumption of more than two servings per week was associated with a decreased risk for neovascular AMD compared with no fish in the diet (OR, 0.49; 95% CI, 0.28 - 0.84). Having more than one four-ounce weekly serving of broiled or baked fish (OR, 0.64; 95% CI, 0.44 - 0.94) or tuna (OR, 0.66; 95% CI, 0.45 - 0.98) also protected against neovascular AMD.

Bausch & Lomb, Inc. helped support this study.

A second study, by W. G. Christen, from Brigham and Women's Hospital in Boston, Massachusetts, and colleagues, showed no protective effect of beta-carotene against AMD. The Physicians’ Health Study I was a randomized, double-blind, placebo-controlled trial of beta-carotene (50 mg every other day) and low-dose aspirin in 22,071 healthy U.S. male physicians aged 40 to 84 years in 1982.

In 21,216 participants without AMD at baseline who were followed for at least seven years, average duration of treatment and follow-up was 12 years. Of 532 cases of confirmed AMD at follow-up, 332 had vision loss to 20/30 or worse. Total AMD developed in 261 subjects in the beta-carotene group and in 271 subjects in the placebo group (relative risk [RR], 0.97; 95% CI, 0.82 - 1.15). AMD with vision loss developed in 160 subjects in the beta-carotene group and in 172 subjects in the placebo group (RR, 0.95; 95% CI, 0.76 - 1.17).

"These randomized trial data from a large population of apparently healthy men indicate that 12 years of beta-carotene supplementation has no appreciable effect on [AMD] during the treatment period," the authors write. "The width of the 95% CI suggests that this large-scale randomized trial can reliably exclude benefit or harm greater than 15-25%."

AstraZeneca, Bayer, Bristol-Myers Squibb, GlaxoSmithKline, McNeil, and Novartis have financial arrangements with one or more study authors.

In the third study, by K. A. Trivedi and colleagues from Harvard Medical School in Boston, Massachusetts, women with a higher dietary intake of omega-3 fatty acids were at decreased risk of developing dry eye syndrome (DES).

Of 39,876 women participating in the Women's Health Study, 32,470 female health professionals aged between 45 and 84 years provided information on diet and DES. The highest versus the lowest dietary intake of omega-3 fatty acids was associated with decreased risk of DES (OR, 0.83; 95% CI, 0.70 - 0.98; P for trend = 0.04), after adjustments for age, other demographic factors, postmenopausal hormone therapy, and total fat intake.

Tuna fish consumption also had a protective effect against DES, and results were similar in other models after adjustments for diabetes, hypertension, and connective tissue diseases.

"Although this is the first study that has evaluated this relationship, and confirmation from other studies is needed, the findings are consistent with clinical observations and postulated biological mechanisms," the authors write. "Thus, further research on the role of omega-3 fatty acids in the prevention and/or treatment of DES would be of interest."

Advanced Vision Research, Inc., supported this study and has financial arrangements with its authors.

ARVO 2003 Annual Meeting: Abstract 811/B786, presented May 4, 2003; abstracts 2111 and 2112, presented May 6, 2003.

Reviewed by Gary D. Vogin, MD

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