Allen Taylor, PhD
Allen Taylor, PhD, is professor at the Friedman School of Nutrition Science and Policy, senior scientist and director of the Laboratory for Nutrition and Vision Research, Tufts University, Boston, Massachusetts.
Piling on yet more evidence as to why it is important to limit processed foods in your diet, new research findings suggest a possible connection between consumption of junk food and development of Age-related macular degeneration (AMD), the leading cause of vision loss in adults age 60 and older. Where earlier studies showed that a diet rich in antioxidants — lots of fruits and vegetables — can lower the risk of AMD, new research shows that eating large quantities of foods high on the glycemic index (the measure of how fast carbohydrates raise blood sugar) actually increases the likelihood of AMD development and progress.
These studies took place at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University in Boston. Senior author Allen Taylor, PhD, and first author Chung-Jung Chiu, DDS, PhD, and colleagues, analyzed data including detailed dietary histories from 4,099 men and women who had participated in the nationwide Age-Related Eye Disease Study (AREDS). The data showed that in the 20% of people whose diets were highest in high-glycemic foods there was a 40% increased risk of AMD versus the people making up the 20% whose diets were lowest in those foods. Furthermore, the researchers found that the risk of developing AMD escalated right along with the glycemic index — the more high-glycemic carbs people regularly ate, the greater the odds they developed AMD.
I spoke with Dr. Taylor about the study findings. He speculates that high-glycemic foods may be especially damaging to many proteins in the eye tissue. Retina pigmented epithelia cells operate like the “kidney” of the retina — that is, they are meant to absorb and then eliminate damaged material, or what Dr. Taylor calls “junk.” There is a mechanism to remove these damaging molecules within eye tissue cells, but the system slows with age. Dr. Taylor suspects that the high-glycemic carbs are harmful in two ways — by altering retina and lens proteins so they’re not as easily recognized by the protein editing machinery, and also compromising the ability of this system to do its work. The result is that high-glycemic foods become a double-whammy to the health of aging eyes.
Improvement doesn’t require radical change in the diet, stresses Dr. Taylor. A simple switch from white foods to their whole-grain counterparts and avoiding high-sugar foods (including those that are sweetened with high fructose corn syrup) can help. Visit lpi.oregonstate.edu/infocenter/foods/grains/gigl.html for more information on high-glycemic index foods.