Lutein (Latin luteus meaning "yellow") is a Xanthophyll and one of 600 known naturally occurring Carotenoids. Lutein is synthesized only by plants and like other Xanthophylls is found in high quantities in green leafy vegetables such as Spinach, Kale and Yellow Carrots. In green plants, Xanthophylls act to modulate light energy and serve as non-photochemical quenching agents to deal with triplet Chlorophyll (an excited form of Chlorophyll), which is overproduced at very high light levels, during photosynthesis. Lutein may play a role in Haidinger's brush, an entoptic phenomenon that allows humans to detect polarized light.

Some foods which are considered as a good sources of the Lutein are Nasturtium (yellow flowers, lutein levels only), Kale (raw), Kale (cooked), Dandelion leaves (raw), Nasturtium (leaves, lutein levels only), Turnip greens (raw), Spinach (raw), Spinach (cooked), Swiss Chard (raw or cooked), Turnip Greens (cooked), Collard Greens (cooked), Watercress (raw), Garden Peas (raw), Romaine Lettuce, Zucchini, Brussels Sprouts, Pistachio Nuts, Broccoli, Carrot (cooked), Maize/Corn, Egg (hard boiled), Avocado (raw), Carrot (raw), and Kiwifruit.

Lutein is called a Carotenoid Vitamin. It is related to β-Carotene and Vitamin A. Foods rich in lutein include broccoli, spinach, kale, corn, orange pepper, kiwi fruit, grapes, orange juice, zucchini, and squash. Lutein is absorbed best when it is taken with a high-fat meal.

Many people think of lutein as “the eye vitamin.” They use it to prevent eye diseases including age-related macular degeneration (AMD), cataracts, and retinitis pigmentosa.

Some people also use it for preventing colon cancer, breast cancer, type 2 diabetes, and heart disease.

Many multivitamins contain lutein. They usually provide a relatively small amount of 0.25 mg per tablet.