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.