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Review: Carotenoids and macular pigments 
Sherena PA, Annamala PT, Mukkadan JK

Carotenoids are important factors in human health. The essential role of beta-carotene and others as the main dietary source of vitamin A and the protective effects of carotenoids against serious disorders such as cancer, heart disease and degenerative eye disease have been recognized .Stimulated intensive research have been carried out into the role of carotenoids as antioxidants and as regulators of the immune response system. The macular pigment of the eye is composed primarily of three xanthophyll pigments, namely (R,R)-lutein, (R,R)-zeaxanthin and (R,S)-zeaxanthin in the order 36, 18 and 18% of the total carotenoid content of the retina along with the remaining 20% consisting of minor carotenoids like oxo-lutein, epi-lutein and ε.ε-carotene- 3,3'-dione. In this review the dietary sources, naming of carotenoids and its isomers were described. Moreover, antoxidant potential of carotenoids, the macular pigments and its transport, bioavailability and the role in eye health were addressed. Evidences suggested that lutein consumption is inversely related to age-related macular degeneration (AMD) and cataract. This was supported by the finding that the diet rich in lutein along with its isomer zeaxanthin which are deposited in the lens and the macula lutea would lower the risk of AMD.

Keywords: carotenoids, cis-trans isomers, bioavailability, macular pigment, eye health, lutein, zeaxanthin, retinitis  
pigmentosa, cataract