What is Lutein? What is its primary function?

Lutein is a xanthophyll which is a type of plant pigment. It is produced by plants and transferred to the animals when they consume plants. Lutein is present in egg yolks and animal fats also. Its primary function is to provides yellow colour to the yolk, fat and skin. It is used in chicken feed to give the broiler yellow coloured skin. Human retina also accumulates lutein which keeps the eyes safe from high energy radiations.