Adapted from Tufts University
Age-related macular degeneration (AMD) and its associated vision loss may be connected to the quality of carbohydrates an individual consumes. In a study published in the July issue of the American Journal of Clinical Nutrition, Allen Taylor, Ph.D., director of the Laboratory for Nutrition and Vision Research at Tufts University, and colleagues confirmed earlier findings linking dietary glycemic index with the risk of developing AMD.
"Men and women who consumed diets with a higher glycemic index than average for their gender and age-group were at greater risk of developing advanced AMD," corresponding author Taylor says. "The severity of AMD increased with increasing dietary glycemic index."
Glycemic index is a scale applied to foods based on how quickly the carbohydrates in foods are converted to blood sugar, or glucose. Foods like white rice, pasta and bread are examples of foods with a high-glycemic-index, meaning that these foods are associated with a faster rise and subsequent drop in blood sugar. Whole wheat versions of rice, pasta and bread are examples of foods that have a low-glycemic-index. These foods are often considered higher quality carbohydrates because they are associated with a slower and less dramatic rise and fall of blood sugar.
"Our findings suggest that 20 percent of the cases of advanced AMD might have been prevented if those individuals had consumed a diet with a glycemic index below the average for their age and gender," notes Taylor.
AMD typically occurs after middle age, although the events which cause it may begin earlier. A leading cause of irreversible visual impairment, AMD results from the gradual breakdown of light-sensitive cells in the central region of the eye's retina, called the macula. Although there is no effective therapy for AMD, dietary intervention may delay its progress. Identifying modifiable risk factors for AMD is becoming increasingly important as the population ages. As Taylor and colleagues point out, the number of people in the United States with visually impairing advanced AMD is expected to double and reach three million by 2020.
"Our results support our hypothesis," says Taylor, "that dietary glycemic index, which has been related to the risk of diabetes, is also associated with the risk and severity of AMD."
Taylor and colleagues conclude that the risk for AMD may be diminished by improving dietary carbohydrate quality, as defined by dietary glycemic index. This may be achieved by relatively simple dietary alterations, such as replacing white bread with whole grain bread. "However," Taylor cautions, "additional studies are needed before we can recommend dietary carbohydrate management as a prevention strategy for AMD."
Macular Degeneration Research, a program of the American Health Assistance Foundation, is proud to fund Dr. Taylor for his follow-up studies concerning this very important research.