Eating fewer refined carbohydrates may slow the progression of age-related macular degeneration, a disease that leads to partial or total blindness in 7 to 15 percent of the elderly, according to a new study from researchers at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University.

Changing your diet may be the easiest way to avoid macular degeneration, says Allen Taylor, director of the Laboratory for Nutrition and Vision Research.

“Dietary changes may be the most practical and cost-effective prevention method to combat progression of age-related macular degeneration, or AMD,” says Allen Taylor, director of the Laboratory for Nutrition and Vision Research at the HNRCA. “It is surprising there is so little attention focused on the relationship between AMD and carbohydrates.”

The study, published recently in the American Journal of Clinical Nutrition, builds on a recent analysis by Taylor and colleagues that found men and women older than 55 whose diets consisted of higher-than-average dietary glycemic index foods appeared to have an increased risk for both early and later stages of AMD.

The dietary glycemic index is a scale used to determine how quickly carbohydrates are broken down into blood sugar, or glucose. Foods with a high glycemic index are associated with a faster rise and subsequent drop in blood sugar. Refined carbohydrates like white bread and white rice have high glycemic indices. Brown rice and bread and pasta made with whole wheat are examples of foods with low glycemic indices.

In the current study, Taylor and his colleagues analyzed diet questionnaires completed by 4,757 non-diabetic men and women participating in the nationwide Age-Related Eye Disease Study, which enrolled people between the ages of 55 and 80 with varying degrees of AMD. The researchers examined the participants’ carbohydrate intake over a one-year period to calculate their glycemic index.

“Our data showed those people in the high-glycemic-index group were at greater risk of AMD progression, especially those already in the late stages,” says coauthor Chung-Jung Chiu, a scientist in the Laboratory for Nutrition and Vision Research and research assistant professor of ophthalmology at the School of Medicine. “Participants who consumed the most refined carbohydrates were 17 percent more likely to develop blinding AMD than the group that consumed the least.”

Public health officials think the rising incidence of AMD could spur a public health crisis in the United States by 2020, when they predict the cases of AMD-related vision loss will have doubled to three million.

“No one has been able to identify an effective noninvasive intervention that will slow the progression of AMD,” says Taylor, who is also a professor at the Friedman School of Nutrition Science and Policy and the School of Medicine. “We feel we have identified a risk factor that could postpone the debilitating loss of vision with very little economic or personal hardship. Based on our data, limiting refined carbohydrate intake for at-risk elderly, such as by limiting sweetened drinks or exchanging white bread for whole wheat, could reduce the number of advanced AMD cases by 8 percent in five years. This can equate to saving the sight of approximately 100,000 people.”