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Enzymes and vision.

While 20/20 vision has become a symbol of visual clarity, between now and the year 2020, more people will experience vision loss, according to the National Eye Institute, based in Bethesda, Maryland, because of aging of the U.S. population.

In the next 10 years, millions of Americans 40 years of age and older are projected to experience some measure of vision resulting from age-related macular degeneration (AMD), glaucoma, cataracts, or diabetes-related vision damage. The macula is a 3-millimeter (mm.) wide yellow spot near the center of the retina that is responsible for the central field of vision.

Significantly, Agricultural Research Service-funded researchers at the Laboratory for Nutrition and Vision Research are finding that healthful eating can reduce health care costs and the incidence of quality-of-life declines from these diseases.

For one study, the researchers analyzed dietary intake and other data from 4,003 men and women, age 55 to 80, who had participated in a long term Age-Related Eye Disease Study (AREDS). The researchers ranked the intake of each of several nutrients consumed during AREDs, then calculated a compound score to gauge their combined dietary effect with links to risk of AMD. The scoring system allowed them to evaluate associations between individual and combined dietary nutrients. They also studied specific food-intake patterns and risks of AMD. The results indicated that regularly consuming a combination of the protective nutrients and a low-glycemic-index diet provided a protective effect against AMD.

A food's glycemic index is an indicator of how fast the carbohydrate content spikes blood glucose levels. The nutrients that were found to be most protective in combination were vitamins C and E, zinc, lutein, zeaxanthin, and the omega-3 fatty acids DHA and EPA.

As the eyes age, oxidized proteins---debris called drusen--begin to accumulate in the macula. A key indicator of AMD risk was finding measurable drusen deposits during a routine examination of the macula, conducted by an eye doctor.


(Sources: Ophthalmology, Molecular Biology of the Cell, May 2009.)

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Publication:Nutrition Health Review
Geographic Code:1USA
Date:Sep 22, 2010
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