The January 14, 2008 issue of the American Medical Association journal Archives of Ophthalmology published the discovery of Harvard researchers that women whose diets are high in lutein, zeaxanthin, and vitamin E have a reduced risk of developing cataracts. Lutein and zeaxanthin are antioxidant xanthophylls which occur in yellow or dark, leafy vegetables. Improved intake of lutein and zeaxanthin has been linked with a lower risk of another eye disease—age-related macular degeneration.
For the current study, William G. Christen, ScD, of Brigham & Women’s Hospital and Harvard Medical School and his colleagues utilized data from 35,551 participants in the Women’s Health Study. Dietary questionnaires completed upon enrollment in 1993 were analyzed for levels of antioxidants including alpha and beta-carotene, beta cryptoxanthin, lycopene, lutein and zeaxanthin, vitamin C and vitamin E in food and multivitamin supplements. The women, who were 45 years of age or older, were followed for an average of 10 years.
Over the course of follow up, 2,031 women developed cataracts. Women whose lutein and zeaxanthin intake was in the top one-fifth of participants experienced an 18 percent lower risk of developing cataracts than women whose intake was in the bottom fifth. When vitamin E was examined, those whose intake was in the top fifth at approximately 262.4 milligrams per day had a 14 percent reduction in risk compared with women whose intake was lowest at only 4.4 milligrams per day. Beta-carotene and vitamin C showed weaker protective associations.
Lutein, zeaxanthin and vitamin E are believed to help protect against cataracts by reducing the formation of damaging free radicals. “The oxidative hypothesis of cataract formation posits that reactive oxygen species can damage lens proteins and fiber cell membranes and that nutrients with antioxidant capabilities can protect against these changes,” the authors explain. Additionally, lutein and zeaxanthin, which exist in the eye’s lens, help filter blue light which can have an adverse effect over time.
“These prospective data from a large cohort of female health professionals indicate that higher intakes of lutein/zeaxanthin and vitamin E are associated with decreased risk of cataract,” the authors conclude. “Although reliable data from randomized trials are accumulating for vitamin E and other antioxidant vitamins, randomized trial data for lutein/zeaxanthin are lacking. Such information will help to clarify the benefits of supplemental use of lutein/zeaxanthin and provide the most reliable evidence on which to base public health recommendations for cataract prevention by vitamin supplementation.”