Lutein is a carotenoid pigment with rich yellow color produced by plants, and found in vegetables, fruits, corn, egg yolk (the yellow color), and the macula in our eyes. Lutein molecule is structurally related to other carotenoid compounds, such as beta-carotene as shown below. All of the 600 compounds in the carotenoid pigments are synthesized in plants from C40 molecules called tetra-terpenes, although some of them are also found in animals. Note that lutein contains oxygen atoms while beta-carotene is purely made of carbon and hydrogen atoms. As exemplified by lutein and beta-carotene, carotenoids can be classified to carotenes (carotenoids without oxygene atom) and xanthophylls (carotenoids containing oxygen atoms). That's why people say lutein is also called xanthophyll, but this is not exactly true: xanthophylls is a subgroup of carotenoids and consists of hundreds of compounds including lutein.