Vitamin E, Lutein May Fight Cataracts

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The new study doesn't claim that lutein/zeaxanthin can prevent cataracts, only that it seems that it may delay their formation, the researchers stressed.

How might the nutrients ease or slow cataracts? Lutein/zeaxanthin are pigments, so they might "absorb harmful radiation coming into the eye from UV radiation," Christen speculated. "They may act as antioxidants as well," preventing cellular damage thought to be caused by free radicals.

Other studies, conducted in both men and women, have looked at the impact of lutein/zeaxanthin and/or vitamin E on cataracts, Christen said. But he said the new 10-year study is one of the longest so far. That's important, he said, because cataracts develop over time. "It appears that we are coming to a critical point where the data are strong enough to suggest a need for a clinical trial" looking at the antioxidants' potential impact on eye health, Christen said.

For its part, the NEI is currently is recruiting subjects from 50 to 85 years of age for a clinical trial on the ability of lutein/zeaxanthin and another antioxidant nutrient, fish oil, to reduce age-related cataracts and macular degeneration. Dr. Emily Y. Chew is leading that study, which she said will be a randomized, controlled trial looking at whether lutein/zeaxanthin, fish oil or a combination of lutein/zeaxanthin plus fish oil are effective.

Chew praised Christen's work as being "another piece of the puzzle that looks toward lutein being helpful." However, while lutein may appear protective in observational studies, that may not pan out in a stricter randomized trial, she said.

John J. McNeil, an Australian epidemiologist who has studied vitamin E and cataracts, agreed that a randomized clinical trial would be more reliable because "observational studies involving nutrients have a mixed record of reliability -- mainly because dietary patterns are so easily confounded by other aspects of lifestyle."

Several randomized clinical studies on vitamin E and cataracts -- including one of his own -- have had disappointing results, added McNeil, who heads the department of epidemiology and preventative medicine at Monash University in Melbourne.