SEEING CONNECTION BETWEEN DIET AND EYE HEALTH

Just as a sliced apple turns brown, the lens of the eye gets brown....

A similarity was suspected between the biochemistry of a browning apple and that of aging eyes--leading to cataracts and age-related macular degeneration (AMD).

Allen Taylor, PhD, director of the Nutrition and Vision Research at Tufts University and colleagues used data from a subset of the Nurses Health Study to explore how carbohydrates in the diet affect vision. They compared information from a decade of dietary questionnaires with eye exams of more than 500 women, ages 53-73. They found women who consumed diets with a relatively high Glycemic Index (GI) had a greater risk of developing signs of early AMD than those with a lower-GI diet.

The Glycemic Index measures how rapidly the body converts a food to sugar. High-GI foods such as sugary foods and beverages, white bread or potatoes are considered lower quality carbohydrates than low-GI foods such as lentils, sweet potatoes, whole grains, fruits and vegetables.

"The types of carbohydrates being consumed were more important than the amounts," explained Taylor. "Simple sugar intake sets the body up for damage when that sugar is oxidized, such as in that rotting apple."

Subsequent research on 4,099 non-diabetic participants in the National Eye Institute's Age-Related Eye Disease Study (AREDS) supported these findings: 20% of AMD cases would have been prevented by consuming a low-GI diet NS 7.8% of new advanced AMD cases would be prevented over 5 years if people consumed a low-GI diet.

Changing your diet from the top half of the Glycemic-Index scale at greatest risk for AMD to the bottom half, is as simple as switching from five slices of white bread daily to five slices of whole wheat bread.

It is hard to overstate the importance of any new tool in the fight against AMD and cataracts. One in three people over the age of 75 develops AMD, the leading cause of blindness for older Americans. As the baby-boomer generation ages and Americans live longer, the incidence of vision problems in those 40 and over is expected to soar- from 3.3 million Americans today to 5.5 million Americans by 2020, according to the National Eye Institute.

"If we could delay the onset of AMD and cataracts for 10 years," says Taylor, "we could eliminate 50% of the associated medical problems."

This research was singled out last summer by the prestigious journal, Science, as an example of how sometimes-controversial federal "earmark" spending pays huge health dividends.