Taking additional antioxidant supplements on top of vitamin C, vitamin E and beta-carotene does little to ward off macular degeneration among older adults, new research suggests.
Researchers found a combination of lutein and zeaxanthin, phytochemicals found naturally in leafy greens, only provided extra protection for people who started out getting the smallest amount of those nutrients in their diets.
Macular degeneration is a chronic eye disease that causes blurred vision and blind spots, which become worse over time; it's the leading cause of blindness in older adults.
Previous research showed a combination of vitamins C and E, beta-carotene and zinc could reduce the risk of advanced macular degeneration by about 25 percent.
For the new study, researchers from the National Eye Institute in Bethesda, Maryland wanted to see if we could improve upon the result.
They added a combination of lutein and zeaxanthin or two types of omega-3 fatty acids to the supplement regimens of some of the original 4,203 study participants, age 50 to 85, who were still taking their initial vitamins and minerals.
Over the next five years, the researchers found, macular degeneration progressed in 29 to 31 percent of study participants, regardless of whether they were given the extra supplements.
People in the study were relatively well educated and tended to have good-quality diets before taking supplements, the researchers noted. As a result, the addition of more antioxidants, and different antioxidants, may not offer any additional benefits.
However, lutein and zeaxanthin may still have an important role in protecting against vision loss for some people. Among study participants who ate the fewest green leafy vegetables, taking those antioxidants was tied to a 26 percent lower risk of progression to advanced macular degeneration.
In the study, 2 percent of people taking beta-carotene developed lung cancer, compared to 1 percent not using that antioxidant. Most of those cancers were in former smokers.
Experts said it would probably make sense going forward to substitute other antioxidants for beta-carotene in recommended formulations with vitamin C, vitamin E and zinc, as lutein and zeaxanthin weren't tied to any complications.
Source: Journal of the American Medical Association, online May 5, 2013.
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