Glycemic Index Indicator of Early AMD

BOSTON--The dietary glycemic index (GI) of consumed food, but not total carbohydrates, is related to risk of age-related maculopathy (ARM), a precursor of age-related macular degeneration (AMD), in a study published in the April issue of the American Journal of Clinical Nutrition (83, 4:880-86, 2006).

Researchers from the Jean Mayer U.S. Department of Agriculture (USDA) Human Nutrition Research Center on Aging at Tufts University investigated the relationship between dietary carbohydrate quality, as measured by dietary glycemic index or total carbohydrate intake, and ARM. The study included 1,036 eyes from 526 Boston-area Nurses' Health Study participants without a previous ARM diagnosis. Researchers used the Age-Related Eye Diseases Study system to classify the presence and degree of ARM, in conjunction with data from an average of four food-frequency questionnaires collected over a 10-year period before the assessment of ARM. They then employed a generalized estimating approach to logistic regression to estimate the odds ratios for ARM, also accounting for the lack of independence between the two eyes from the same subject.

After adjusting for multiple variables, dietary GI was related to ARM (specifically to retinal pigmentary abnormalities), whereas total carbohydrate intake was not. This led researchers to conclude dietary GI may be an independent risk factor for ARM.