SUNDAY, May 5 (HealthDay News) -- Adding omega-3 fatty acids and other nutrients to standard antioxidant vitamins doesn't give older people any added protection against a leading cause of blindness, a new study finds.
The study looked at age-related macular degeneration (AMD), which afflicts millions of older people in the United States, according to background information outlined by the researchers.
The condition is "the leading cause of blindness in the developed world, [and] accounts for more than 50 percent of all blindness in United States," the study authors said.
"Without more effective ways of slowing progression, the number of persons with advanced AMD is expected to double over the next 20 years, resulting in increasing socioeconomic burden," wrote Dr. Emily Chew, of the U.S. National Eye Institute, and colleagues.
Prior research has shown that a blend of the antioxidant vitamins C, E, and beta carotene and zinc could reduce the risk of progression to advanced AMD.
Could adding in more antioxidants boost that protection even higher? To find out, this five-year study of more than 4,000 patients, aged 50 to 85, examined whether adding the carotenoids lutein and zeaxanthin, and the omega-3 fatty acids DHA and EPA to the antioxidant vitamin mixture would further reduce the risk.
It did not, according to the findings published online Sunday in the Journal of the American Medical Association and presented simultaneously at the annual meeting of the Association for Research in Vision and Ophthalmology, in Seattle.
The researchers caution that the findings may be due to a true lack of effectiveness, or they might also be the result of insufficient doses, too short a treatment time, or both.