Zeaxanthin is a carotenoid xanthophyll and is one of the most common carotenoid found in nature. It is the pigment that gives corn, saffron, and many other plants their characteristic color. Zeaxanthin breaks down to form picrocrocin and safranal, which are responsible for the taste and aroma of saffron Carotenoids are among the most common pigments in nature and are natural lipid soluble antioxidants. Zeaxanthin is one of the two carotenoids (the other is lutein) that accumulate in the eye lens and macular region of the retina with concentrations in the macula greater than those found in plasma and other tissues. Lutein and zeaxanthin have identical chemical formulas and are isomers, but they are not stereoisomers. The main difference between them is in the location of a double bond in one of the end rings. This difference gives lutein three chiral centers whereas zeaxanthin has two. A relationship between macular pigment optical density, a marker of lutein and zeaxanthin concentration in the macula, and lens optical density, an antecedent of cataractous changes, has been suggested. The xanthophylls may act to protect the eye from ultraviolet phototoxicity via quenching reactive oxygen species and/or other mechanisms. Some observational studies have shown that generous intakes of lutein and zeaxanthin, particularly from certain xanthophyll-rich foods like spinach, broccoli and eggs, are associated with a significant reduction in the risk for cataract (up to 20%) and for age-related macular degeneration (up to 40%). While the pathophysiology of cataract and age-related macular degeneration is complex and contains both environmental and genetic components, research studies suggest dietary factors including antioxidant vitamins and xanthophylls may contribute to a reduction in the risk of these degenerative eye diseases. Further research is necessary to confirm these observations. (PMID: 11023002). Zeaxanthin has been found to be a microbial metabolite, it can be produced by Algibacter, Aquibacter, Escherichia, Flavobacterium, Formosa, Gramella, Hyunsoonleella, Kordia, Mesoflavibacter, Muricauda, Nubsella, Paracoccus, Siansivirga, Sphingomonas, Zeaxanthinibacter and yeast (https://reader.elsevier.com/reader/sd/pii/S0924224417302571?token=DE6BC6CC7DCDEA6150497AA3E375097A00F8E0C12AE03A8E420D85D1AC8855E62103143B5AE0B57E9C5828671F226801). It is a marker for the activity of Bacillus subtilis and/or Pseudomonas aeruginosa in the intestine. Higher levels are associated with higher levels of Bacillus or Pseudomonas. (PMID: 17555270; PMID: 12147474)