Lutein 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. See xanthophyll cycle for this topic. Animals obtain lutein by ingesting plants.In the human retina, lutein is absorbed from blood specifically into the macula lutea, although its precise role in the body is unknown. Lutein is also found in egg yolks and animal fats.

In the present book, ten typical literatures about Lutein published on international authoritative journals were selected to introduce the worldwide newest progress, which contains reviews or original researches on Lutein. We hope this book can demonstrate advances in Lutein as well as give references to the researchers, students and other related people.