- Diets High in Simple Carbs May Boost Risk of Age-Related Macular Degeneration
Passing on the fries may do more than manage your waistline: Such restraint may also protect your eyes. In a study at Tufts University reported in the American Journal of Clinical Nutrition (Volume 83, page 880), researchers examined the eyes of 526 women between ages 53 and 73. They also examined 10 years’ worth of data about the women's diets, collected as part of the Nurses Health Study.
Women whose diets had the highest glycemic index, they found, had double the risk of the early form of age-related macular degeneration called age-related maculopathy (ARM) of women who ate low-glycemic index diets. Glycemic index measures how quickly a food makes blood sugar rise. White or refined carbohydrates -- sugar, potatoes, white flour -- have a much higher glycemic index than brown rice, whole-wheat breads and pastas, or legumes like lentils. The amount of carbohydrates that a woman ate, however, made no difference -- suggesting that the quality of carbohydrates, not their quantity, matters most. Still, the researchers are quick to point out that the study does not necessarily mean that simple carbohydrates like sugar cause age-related macular degeneration. It could be that those who pile their plates with fries tend to have an overall health pattern that isn’t healthy -- although researchers adjusted their findings to exclude other high-risk factors for age-related macular degeneration such as cigarette smoking and obesity.
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Genetic Factors plus Lifestyle Influence the Risk of Age-Related Macular Degeneration
For some time, researchers have known that age-related macular degeneration has a genetic component. A group of Boston researchers has identified a new gene variant as well as the link between variants in three genes, all of which seem to play a part in causing age-related macular degeneration.
In 2005, scientists found that variations in a gene coding for the protein Complement Factor H (CFH) were common in people with age-related macular degeneration, one of which appeared to account for 43% of the risk for age-related macular degeneration. CFH itself likely protects blood vessels -- including those in the eye -- from inflammation and damage.
Further research identified variants of another gene, BF/C2, that also affect age-related macular degeneration. In the more recent Boston study the researchers have located yet another CFH variant associated with age-related macular degeneration by analyzing samples from more than 2,000 people of European descent over age 60, more than half of whom had either wet or dry age-related macular degeneration.
Another study by members of the same team showed that, among patients in the major AREDS trial (Age-Related Eye Disease Study) these genetic subtypes interact strongly with lifestyle risk factors for age-related macular degeneration such as smoking and body mass index. Overweight smokers with one genetic type had the highest risk of all. Not only may these findings someday help explain age-related macular degeneration, but they might inspire new treatments, too. These findings were reported in the journal Nature Genetics (Volume 38, page).
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