Boston-- Age-related macular degeneration (AMD) is one of the leading causes of vision loss in older adults and a person's risk may partly depend upon diet. When it comes to carbohydrates, quality rather than quantity may be more important, according to new research by Allen Taylor, PhD, director of the Laboratory for Nutrition and Vision Research at the Jean Mayer USDA Human Nutrition Research Center on Aging (HNRCA) at Tufts University, and colleagues. Their findings were reported in the April 2006 issue of the American Journal of Clinical Nutrition.
Taylor and colleagues analyzed data from a sub-group of participants in the Nurses' Health Study (NHS) who were enrolled in the Nutrition and Vision Program. The researchers looked at the total amount of carbohydrates consumed over 10 years and the dietary glycemic index, which is a measure of the quality of overall dietary carbohydrate.
"Women who consumed diets with a relatively high dietary glycemic index had greater risk of developing signs of early age-related macular degeneration when compared with women who consumed diets with a lower dietary glycemic index," says lead author Chung-Jung Chiu, DDS, PhD, scientist in the Laboratory for Nutrition and Vision Research at the HNRCA and an assistant professor at Tufts University School of Medicine. High total carbohydrate intake, however, did not significantly increase the risk factor for AMD.
"In other words, the types of carbohydrates being consumed were more important than the absolute amount," explains Taylor, senior author. A high-glycemic-index diet is one that is rich in high-glycemic-index foods, which are converted more rapidly to blood sugar in the body than are low-glycemic-index foods.
You can lower your average dietary glycemic index in all sorts of ways. For example, the sticky rice served in Chinese restaurants has a very high glycemic index (i.e. it gets digested and the sugar in it passes into your bloodstream very quickly). Whereas Basmati rice is much lower and Uncle Ben's converted rice is lower stilll. Similarly, the types of wheat used to make bread have much higher glycemic index than the types of wheat used to make pasta and whole grain generally is lower than white bread. The idea where is that you don't have to give up a major grain. You can just shift toward subtypes that have lower glycemic index.
Rick Mendosa has a great online list of foods and their glycemic indexes. Go study it. Also, read his introduction to glycemic index which offers all sorts of insights about why foods vary in glycemic index. Note that in the scaling he uses 100 is the index for glucose. The low range starts at 55 and goes down into the 30s and 40s for some grains and beans. Higher amylose grains have lower glycemic indexes because amylose starch is broken down fairly slowly in the digestive tract. I wish rices came with an amylose rating on the bag. Then purchase of a rice with 27% or 28% amylose would assure you are getting a low glycemic index variety. Note how he lists a low amylose corn muffin with a glycemic index of 102 and a high amylose corn muffin with a glycemic index of 49. Huge difference. Though the latter number might be due to rolled oats in the recipe.
The Wikipedia Glycemic Index page is worth a read as well.
|Share |||Randall Parker, 2006 June 06 07:37 PM Aging Diet Eye Studies|