The carotenoid xanthophylls - lutein and zeaxanthin - have been shown to offer protection from age-related macular degeneration, a disease of the eye that can lead to blindness. Now researchers at Ohio State University have revealed that the nutrients can also help prevent cataracts.
In the current study, reported in the December 2004 issue of the Journal of Nutrition, human eye cells were treated with several concentrations of lutein, zeaxanthin or vitamin E, and exposed to ten seconds of ultraviolet-beta radiation (UVB). Ultraviolet-beta radiation is a wavelength of sunlight that is believed to be responsible for cataract formation. An additional group of cells was not pretreated.
The team found that although vitamin E had a protective effect, lutein and zeaxanthin were nearly ten times more powerful. Vitamin E reduced signs of damage by 25 to 32 percent compared to that observed in the untreated cells, while lutein and zeaxanthin reduced the damage by 50 to 60 percent at a concentration ten times less than that of vitamin E.
Ohio State University assistant professor of nutrition and study coauthor Dr. Joshua Bomser explained, “The lens is equipped with antioxidant defense mechanisms designed to guard against the harmful effects of ultraviolet radiation and oxidative stress. In addition to protective enzymes and compounds like vitamins C and E, we think that low concentrations of lutein and zeaxanthin in the eye lens help shield the eye from the harmful effects of UVB radiation."
“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," Dr Bomser noted. "Our results are the first to provide physical evidence suggesting that lutein and zeaxanthin decrease damage caused by ultraviolet radiation.
Journal of Nutrition, December 2004.