Carbs High on the Glycemic Index May Increase Age-Related Macular Degeneration
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Reviewed By Louise Chang, MD
July 13, 2007 -- Eating lots of sugary, starchy foods may make eyes more vulnerable to age-related macular degeneration (AMD), America's top cause of vision loss.
That news appears in The American Journal of Clinical Nutrition.
AMD typically starts late in life. It affects the retina, located in the center of the eye. AMD can cause vision loss.
Previous research shows that diets rich in antioxidants might help prevent AMD.
The new study adds one more diet tip: Go for carbohydrates that don't make your blood sugar spike quickly.
Doing so might help prevent AMD, note the researchers. They included Chung-Jung Chiu, DDS, PhD, and Allen Taylor, PhD. They work in Boston at Tufts University's Jean Mayer U.S. Department of Agriculture Human Nutrition Research Center on Aging.
Nearly 4,100 U.S. adults aged 55-80 took part in the study. They completed dietary surveys and had their eyes checked for AMD.
The dietary surveys listed 90 foods. Participants noted how often and how much of those foods they typically ate.
The researchers paid close attention to the glycemic index -- a measure of how much certain foods raise blood sugar.
Sugary items and refined grains (such as white flour, which has the bran stripped out of it) are examples of foods that rank high on the glycemic index. Whole grains, legumes, and vegetables rank lower on the glycemic index.
Glycemic Index and AMD
The researchers tracked AMD by eye, not participant, because some people may have had AMD in one eye but not the other.
Most eyes showed no signs of AMD. But 602 eyes had advanced AMD.
People with the diets highest on the glycemic index were the most likely to have advanced AMD in at least one eye.
Those findings held when the researchers considered participants' age, gender, and other risk factors.
The study doesn't show exactly what caused AMD. It's not clear that diet was solely responsible for any cases of AMD. Participants weren't followed over time, and they weren't asked to change their diets for the study.
However, the researchers estimate that a fifth of the advanced AMD cases in their study might have been prevented by eating foods low on the glycemic index.
SOURCES: Chiu, C. The American Journal of Clinical Nutrition, July 2007; vol 86: pp 180-188. WebMD Medical Reference: "Understanding Macular Degeneration -- the Basics." WebMD Health News: "Healthy Diet May Help Seniors' Vision." WebMD Medical Reference: "Glycemic Index: Good vs. Bad Carbs." News release, Tufts University.
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