Protection for Aging Eyes
August 31, 2006—Good news for seniors interested in protecting their eye health: the omega-3 fatty acids in fish and certain plant foods may protect aging eyes against macular degeneration, the leading cause of blindness for people 65 and older.
Two new studies, published in the Archives of Ophthalmology, confirm that a diet high in the omega-3 polyunsaturated fats EPA (eicosapentaenoic acid), DHA (docosahexaenoic acid), or alpha-linolenic acid protects against both early and late forms of age-related macular degeneration, also known as age-related maculopathy (ARM).
Age-related macular degeneration is a deterioration of the retina, the layer of the eye that contains cells that send visual images through the optic nerve to the brain. The central portion of the retina, known as the macula, is responsible for the detailed central vision that allows people to read, drive, and recognize faces. Degeneration of the macula causes objects in the central field of vision to appear blurred.
“We currently lack effective treatments for early ARM and a high proportion of late ARM cases,” said Paul Mitchell, MBBS, MD, PhD, director of the Centre for Vision Research at the University of Sydney and author of the Blue Mountains Eye Study. In older Australians, those with the lowest intake of omega-3 fatty acids (in particular alpha-linolenic acid) had about a 70% increased likelihood of early macular degeneration compared with most of the population reporting a moderate intake.
A total of 3,654 people 49 years or older participated in the Blue Mountains Eye Study from 1992 to 1994; after five years, 2,335 (75% of survivors) were re-examined. At the beginning of the study, 2,895 people (79%) filled out a questionnaire about their dietary habits. Age-related macular degeneration was determined using retinal photographs.
A 40% reduction in the incidence of early age-related macular degeneration was associated with eating fish at least once a week; eating fish at least three times per week even reduced the incidence of late-stage age-related macular degeneration.
Similar results were reported in a large study of male twins conducted at Harvard Medical School. The study population came from the National Academy of Sciences–National Research Council World War II Veteran Twin Registry. The study included 681 twins: 222 twins with intermediate or late stages of age-related macular degeneration (grade 3, 4, or 5) and 459 twins with either no macular abnormalities or with early signs of macular abnormalities (grade 1 or 2). Those who ate the highest amounts of omega-3 fatty acids had about half the risk of age-related macular degeneration as those who consumed the least. As in the Australian study, these findings were especially pronounced among those people who ate the least amounts of alpha-linolenic acid, an essential fatty acid found in flax seeds, pumpkin seeds, and walnuts.
Smoking raises risk
The Harvard study also confirmed a well-known fact about age-related macular degeneration: cigarette smoking increases the risk.
“In our study of twins, we found that current and past cigarette smoking increases risk for AMD,” said Johanna M. Seddon, MD, ScM, of the Massachusetts Eye and Ear Infirmary and lead author of the study. “Current smokers had almost a 2-fold increased risk of AMD and past smokers had a 1.7-fold increase in risk in comparison with those who never smoked.”
Forty-six million Americans continue to smoke each year, and 28.5% of these current smokers are individuals between the ages of 18 and 24, leaving future generations at risk for diseases such as cardiovascular disease and age-related macular degeneration. Smoking increases inflammatory responses and oxidative stress, both of which contribute to age-related macular degeneration development.
(Arch Ophthalmol 2006;124:995–1001; Arch Ophthalmol 2006;124:981–86)
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Jeremy Appleton, ND, CNS, is a licensed naturopathic physician, certified nutrition specialist, and published author. Dr. Appleton was the Nutrition Department Chair at the National College of Naturopathic Medicine, has served on the faculty at Bastyr University of Natural Health Sciences, and is a former Healthnotes Senior Science Editor and a founding contributor to Healthnotes Newswire. He has worked extensively in scientific and regulatory affairs in the supplement industry and is now a consultant through his company Praxis Natural Products Consulting and Wellness Services.
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