Lutein is a xanthophyll, i.e., an oxygenated carotenoid that all mammalians, humans included, derive from their diet because they are unable to synthesize carotenoids. Several studies have shown that high Lutein intake, either through diet or as nutritional supplement, has beneficial effects on eye diseases, preventing or even improving both age-related macular degeneration (AMD) and cataract.
http://www.sldcarotene.com/lutein/
