Nutrition’s Potential to Save Sight

While 20/20 vision is a symbol of visual acuity, between now and the year 2020, more and more people will experience some extent of vision loss due to age-related macular degeneration (AMD) and other sight-robbing diseases.
Now, Agricultural Research Service (ARS)-funded scientists at the Laboratory for Nutrition and Vision Research are finding that healthy eating can reduce not only health care costs, but also the decline of quality of life due to these diseases. The laboratory, directed by Allen Taylor, is part of the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University in Boston, Mass.
One study indicated that regularly consuming a combination of protective nutrients and a low-glycemic-index, or “slow carb,” diet provided an AMD protective effect. A food’s glycemic index is an indicator of how fast the carbohydrate it contains will spike blood sugar levels. The macula is a 3-millimeter-wide yellow spot near the center of the retina responsible for the central field of vision.
For the study, the researchers analyzed dietary intake and other data from more than 4,000 men and women, aged 55 to 80, who had participated in the long-term Age-Related Eye Disease Study, or AREDS. Led by Chung-Jung Chiu, the researchers ranked intake of each of several nutrients consumed during the AREDS study, then calculated a compound score to gauge their combined dietary effect on the risk of AMD. The scoring system allowed them to evaluate associations between individual–and combined–dietary nutrients.
The nutrients that were found to be most protective in combination with the low-glycemic-index diet were vitamins C and E, zinc, lutein, zeaxanthin, and the omega-3 fatty acids known as DHA and EPA. The 2009 study was published in Ophthalmology.
Read more about this and other research related to improving health through nutrition in the July 2010 issue of Agricultural Research magazine, available online at: http://www.ars.usda.gov/is/AR/archive/Jul10/sight0710.htm.
ARS is the principal intramural scientific research agency of the U.S. Department of Agriculture (USDA).

Greater intake of several nutrients combined with low-glycemic foods linked to reduced risk of macular degeneration

Researchers analyzed data from 4,003 participants in the Age-Related Eye Disease Study (AREDS). Information was collected on the subject’s intake of several nutrients related to eye health, including vitamin C, vitamin E, zinc, lutein/zeaxanthin, and the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

Glycemic index was calculated for consumed food items. Photographs of the macula of the eye (taken upon enrollment) were graded for severity and type of macular degeneration.
Participants with a high overall intake of the associated nutrient group, as well as higher intakes of low-glycemic foods, had the lowest risk of early or advanced macular degeneration. When single nutrients were analyzed separately, vitamin E emerged as significantly protective against the disease..
The study is the first to analyze the combination of multiple nutrient groups and a low-glycemic diet on the risk of age-related macular degeneration.
Ophthalmology. May 2009. 116:5(939-946).