Carotenoids have two key roles in plants and algae: they absorb light energy for use in photosynthesis, and they protect chlorophyll from photodamage. Beta-carotene is the most common form in plants.
Some carotenoids have vitamin A activity (so they can convert to retinol). These and other carotenoids can also act as antioxidants. In the eye, certain other carotenoids (lutein, astaxanthin, and zeaxanthin) apparently act directly to absorb damaging blue and near-ultraviolet light. This protects the macula of the retina, the part of the eye with the sharpest vision.
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- Armstrong G.A. & Hearst J.E. (1996). "Carotenoids 2: Genetics and molecular biology of carotenoid pigment biosynthesis". FASEB J. 10 (2): 228–37. PMID 8641556.
- Kidd, Parris (2011). "Astaxanthin: cell membrane nutrient with diverse clinical benefits and anti-aging potential" (PDF). Alternative Medicine Review. 16 (4): 335–364. Archived from the original (PDF) on 2016-07-31. Retrieved 2016-01-13.