FRESNO, CA - Eating grapes may help protect eye health, according to new research published in the journal Nutrition. The study showed that a diet supplemented with grapes was able to counter damage from oxidative stress and preserve retinal structure and function in a laboratory model of retinal degeneration. Natural components in grapes that help promote antioxidant activity are thought to be responsible for these beneficial effects, in keeping with previous studies that indicate grape-derived compounds are biologically active in the retina.
The retina is the part of the eye that contains the cells that respond to light, known as photoreceptors. There are two types of photoreceptors: rods and cones. Retinal degenerative diseases cause progressive photoreceptor death and irreversible vision impairment, including blindness, affecting millions of people in the U.S. Elevated oxidative stress is strongly associated with retinal disease and has been widely studied in the development of age-related macular degeneration and other retinal degenerations.
In this new grape study, researchers at the Bascom Palmer Eye Institute at the University of Miami Miller School of Medicine, investigated whether a diet supplemented with grapes, in the form of whole grape freeze-dried powder, would protect the photoreceptors of the retina from degeneration induced by acute oxidative stress. Mice were either fed the grape-supplemented diet (corresponding to about 3 servings per day for humans), a sugar-matched control diet, or a normal chow control diet.
The results showed that both retinal structure and function were preserved in the group consuming the grape-enriched diet. Specifically, the grape-consuming group maintained their retinal thickness, the quantity of photoreceptors, and the amount of photoreceptor activity, despite the oxidative stress insult. Conversely, in the non-grape consuming group, retinas were damaged, displaying holes and lesions, and with a significant decrease in thickness. Additionally there was a 40% reduction in photoreceptors and significant loss of photoreceptor activity.
"Adding grapes to the diet actually preserved retinal health in the presence of oxidative stress in this study," said Abigail S. Hackam, Ph.D., lead investigator of the study. "These results are very exciting and build on the growing evidence that suggests a very real benefit for grape consumption and eye health." Hackam, an associate professor of ophthalmology, focuses her research on the cellular mechanisms of retinal development and degeneration.