What is Astaxanthin Astaxanthin is a carotenoid that occurs naturally in algae, shrimp, lobster, crab, wild salmon, and krill. Carotenoids are organic colorants that provide antioxidant properties along with a red orange hue. Unlike other carotenoids, astaxanthin is able to interface with both water and fats. Its unique structure gives astaxanthin the ability to to address numerous free radicals at a time, which makes it a potent antioxidant, as well as to work on numerous inflammatory pathways, giving the carotenoid anti-inflammatory properties.