lutein

Lutein is a naturally occurring yellow pigment that belongs to the carotenoid family, specifically a xanthophyll. It is not considered a provitamin A compound. In humans, lutein is valued primarily for its presence in the macula, a part of the retina, where it contributes to the macular pigment that helps protect eye tissue from damage caused by blue light and oxidative stress.

Chemically, lutein is a long-chain, oxygen-containing carotenoid with two hydroxyl groups, giving it particular solubility and distribution characteristics. It is fat-soluble and cannot be synthesized by humans, so it must be obtained from the diet. The molecular form most commonly found in foods and supplements is the all-trans isomer, with bioavailability influenced by food fat and processing.

Dietary sources of lutein include leafy green vegetables such as kale, spinach, and collards, as well as corn, yellow peppers, and egg yolk. Cooking can improve release from plant matrices, and fat enhances intestinal absorption. After absorption, lutein is carried in lipoproteins and transported to tissues, including the retina, liver, and adipose tissue, where it is stored or utilized.

Lutein, together with zeaxanthin, constitutes the macular pigment, which helps filter blue light and neutralize reactive oxygen species in the eye. Observational studies have linked higher lutein intake or macular pigment levels with lower risk of age-related macular degeneration and cataract progression, though evidence from randomized trials is mixed regarding disease prevention.

Supplements containing lutein, often with zeaxanthin, are marketed for eye health. Typical supplemental doses range from 5 to 20 milligrams daily. Lutein is generally regarded as safe; excessive intake can cause carotenoid-related skin discoloration. In plants, lutein is synthesized via the isoprenoid carotenoid biosynthesis pathway and serves roles in photosynthesis and photoprotection.