May 9, 2009 A diet that includes key nutrients and low-glycemic index foods is likely to reduce risks for age-related macular degeneration (AMD), according to the first study to analyze these factors in combination. Chung-Jung Chiu, PhD, of the Laboratory for Nutrition and Vision Research, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, led this new analysis of Age-Related Eye Disease Study (AREDS) data.
The study team included AREDS researchers and was funded in part by the United States Department of Agriculture (USDA) and the National Institutes of Health (NIH). Earlier studies—including AREDS and the Nutrition and Vision Project of the Nurses’ Health Study—had revealed the AMD-protective effects of several nutrients and of a low-glycemic index (GI) diet, but Chiu’s study is the first to associate specific food intake patterns with substantial AMD risk reductions.
Study participants whose diets included higher levels of protective nutrients and of low-GI foods were at lowest risk for early and advanced AMD. This eye disease affects the retina, the sensitive tissue at the back of the eye that transmits images to the brain; advanced AMD can destroy the detailed, central vision people need to read, drive, and enjoy daily life. Data was analyzed for 4,003 AREDS participants, involving 7,934 eyes. Levels of AMD-protective nutrients, including vitamins C and E, zinc, lutein, zeaxanthin, omega-3 fatty acids (DHA and EPA), as well as low-GI foods, were assessed using participants’ food intake reports. (A food’s GI value is based on how fast its carbohydrates raise the body’s blood sugar levels; low GI foods have less impact on blood sugar fluctuations.) Each dietary factor was assigned a percentile score, and factor scores were added up to find each participant’s compound score. Compound scores were related to participants’ AMD risk, based on diagnostic eye photographs taken when they joined AREDS. Beta-carotene, assessed in this and earlier studies, did not affect risk levels in this analysis.
“Although the compound score may be a useful new tool for assessing nutrients in relation to AMD, specific dietary recommendations should be made only after our results are confirmed by clinical trials or prospective studies,” Dr. Chiu said.
AMD research is intensifying because the most susceptible population, people over age 60, is growing. A new report estimates 18 million will have AMD by 2050, 1.6 million of whom will be legally blind. Advanced AMD, especially the most prevalent “dry” form (geography atrophy), is a leading cause of severe vision impairment, and treatment options are limited. Preventing AMD and delaying disease progression would best preserve people’s quality of life while containing healthcare system cost and care challenges. Food sources of nutrients that support good general and eye health include: citrus fruits, vegetable oils, nuts, whole grains, dark green leafy vegetables, and cold water fish.
This research was published in the May issue of Ophthalmology, the journal of the American Academy of Ophthalmology.
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