Vitamin manufacturers often add the antioxidants lutein and zeaxanthin to their products, but until now there has been no biochemical evidence to support the claim that these substances help protect the eyes, said Joshua Bomser, a study co-author and an assistant professor of nutrition at Ohio State University. Some studies have suggested that these antioxidants boost eye health.
Results from laboratory experiments on human lens cells showed that lutein and zeaxanthin, antioxidants found in plants such as kale, spinach and collard greens, helped to protect the cells from exposure to ultraviolet light a leading cause of cataract formation.
The researchers compared the effects of these antioxidants to vitamin E, an antioxidant also thought to reduce the onset of eye diseases.
Lutein and zeaxanthin were nearly 10 times more powerful than vitamin E in protecting the cells from UV-induced damage.
Nearly 20 million people in the United States suffer from cataracts a condition where the lens of the eye clouds over, making it difficult or nearly impossible to see. Current treatment is expensive and involves a surgical procedure that is performed more than 1.5 million times each year at an estimated cost of $3.4 billion.
"Along with the many environmental, lifestyle and genetic risk factors associated with cataracts, exposure to ultraviolet radiation from sunlight and oxidative stress appear to be the most relevant in this disease," Bomser said. "Our results are the first to provide physical evidence suggesting that lutein and zeaxanthin decrease damage caused by ultraviolet radiation."
The study appears in the current issue of the Journal of Nutrition.