Lutein is one of the most widespread naturally occurring carotenoids — a yellow xanthophyll pigment found in many foods, particularly in fruits and vegetables such as leafy greens (spinach, kale), corn and marigold flowers. It accumulates in the human macula, where as macular pigment it filters blue light and is marketed in supplements for eye health and age-related macular degeneration. In food technology, lutein-rich extracts (often from marigold, E161b) serve as natural yellow colourants for beverages, dairy, bakery and confectionery. Like all carotenoids it is sensitive to light, heat and oxidation, so processors use encapsulation, antioxidants and opaque, cool storage to protect colour and potency.