astaxanthin

Astaxanthin is a carotenoid pigment in the xanthophyll subclass. It is a keto-carotenoid with the molecular formula C40H52O4, characterized by a long conjugated polyene chain and two terminal rings that bear hydroxyl and keto groups. The combination of these functional groups and the extended double-bond system gives astaxanthin its red to pink color and strong antioxidant activity, and makes it highly lipophilic.

Astaxanthin occurs naturally in microalgae, most notably Haematococcus pluvialis, and is accumulated in aquatic organisms such as salmonid fish and crustaceans like shrimp and krill. Commercial astaxanthin is produced by extraction from microalgae or by chemical synthesis; increasingly, microalgal cultivation and fermentation provide sustainable sources. In aquaculture, astaxanthin is fed to salmonid fish to color their flesh and to crustaceans to color shells.

Use as a dietary supplement for humans is common, with claims of antioxidant and anti-inflammatory effects; however, evidence varies by outcome. In food and feed, astaxanthin functions as a colorant and antioxidant. It is generally regarded as safe when used at approved levels in foods and dietary supplements in many countries; potential side effects are rare at typical doses.