Best Lutein features Biolut Marigold extract, a potent source of lutein standardized to contain 90% lutein esters, equivalent to 45% free lutein. Marigold flowers are the most abundant source of lutein in nature. The esterified lutein in Biolut Marigold extract is easy to absorb and highly bioavailable. Each capsule provides 20 mg of free lutein. Lutein is a yellow member of the carotenoid family. It is one of the major carotenoids found in human blood, with a high tissue concentration in the retina (and macula) of the human eye. Lutein functions as a potent free radical scavenger in a number of tissues, including the eyes, skin, heart and lungs