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Study: Some High-Sugar Foods Linked To Vision Loss

Study: Some High-Sugar Foods Linked To Vision LossA recent study by Tufts nutrition researchers found that the development of age-related macular degeneration may be tied to over consumption of certain carbohydrates.

Boston [07.24.07] Doctors have already found many reasons to recommend decreased consumption of foods such as white bread and sugary snacks. However, a new study by Tufts University researchers adds another reason to the list.

Research led by Allen Taylor, director of the Laboratory for Nutrition and Vision Research at the USDA Human Nutrition Research Center on Aging (USDA HNRCA) at Tufts, determined that eating certain types of carbohydratesmight contribute to the development of age-related macular degeneration (AMD) and associated vision loss later in life.

Age-related macular degeneration, a leading cause of blindness, typically manifests after middle age, though it can be influenced by events earlier in life. It is caused by the breakdown of cells in the retina of the eye. According to Taylor and Chung-Jung Chiu, scientist at the USDA HNRCA and professor at the Tufts University School of Medicine, the number of people with AMD could double and reach three million by 2020.

"Sugar [in carbohydrates] is fuel for the cells, but too much is destructive," Taylor, who is also a professor at the Friedman School of Nutrition Science and Policy and Tufts University School of Medicine, told The New York Times. As reported by WebMD, Taylor and colleagues' study suggests that people "go for carbohydrates that don't make your blood sugar spike quickly."

Simple carbohydrates, found in many processed or sweetened foods such as cake or pasta, possess a high-glycemic-index, which means they are broken down quickly in the body, resulting in a rapid rise of sugar in the blood. Complex carbohydrates, found in foods such as whole wheat bread and beans, generally have a low-glycemic-index because they are metabolized more slowly, causing a less dramatic rise of sugar in the blood.

In Taylor's study, people consuming diets with a higher-than-average glycemic index faced a greater risk of developing AMD, as dietary glycemic index was directly proportional to the severity of AMD. However, the researchers note, that the study did not specifically determine the cause of AMD among subjects, nor did it pinpoint diet as the sole cause of their vision loss. The study was published in the July edition of the American Journal of Clinical Nutrition.

"The researchers suggest that a fifth of cases of advanced AMD might be avoided if individuals dropped high-GI foods such as white bread, sugary cereals and mashed potato," reports The Times, London. Or as Taylor explains in a statement, "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." The study surveyed more than 4,000 men and women between the ages of 55 and 80 participating in the nationwide Age-Related Eye Disease Study.

"It is known from laboratory studies that carbohydrates can damage the proteins in cells and affect their function," Taylor told the The New York Times. "The sugars actually modify things, modify the proteins, and it's the accumulation of this modified stuff that is poisonous to cells." According to the The New York Times, additional research has also found that increased consumption of foods with a high glycemic index could lead to diabetes, cardiovascular disease and certain types of cancer.

Taylor and colleagues believe that high blood sugar concentrations among people consuming a high-glycemic-index diet may advance AMD by contributing to the breakdown of retinal cells and the inflammation or damage of blood vessels that supply the eyes, The New York Times reported.

Diet, however, is not a currently a leading cause of AMD;aging, smoking and education level are more significantly linked, the researchers told the The New York Times. Taylor and colleaguesalso note that further long-term studies are needed to more comprehensively explore the relationship between diet and AMD.

In the meantime, cutting back-but not cutting out-the consumption of simple carbohydrates could help save your vision later in life.

"People are eating more simple sugar than they used to, and reverting to a diet that is more fruits and vegetables and less sweetened food would help," Taylor told the The New York Times. "It doesn't take a lot of change."

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