Carotenoids are a group of naturally occurring phytochemicals that are structurally related to alpha-carotene. They are antioxidants with a number of health benefits and mostly found in fruits and vegetables. The combined concentrations of lutein and zeaxanthin are generally higher than the concentrations of the carotenes in most food sources..
While both alpha-carotene and beta-carotene are precursors of vitamin A, lutein and zeaxanthin are not. However, the hydroxyl groups of lutein and zeaxanthin make the chemicals more hydrophilic than the carotenes so that they can react with singlet oxygen radicals in water.
- (2004) "Lutein and Zeaxanthin and Their Potential Roles in Disease Prevention". Journal of the American College of Nutrition 23 (Supplement 6): 567S.