Astaxanthin is produced naturally by aquatic algae and taken up by the animals who feed on them, such as salmon, krill, and flamingos, giving them their reddish color. Astaxanthin is a powerful antioxidant. As such, it likely plays a role in health in many different manners, including improved mitochondrial function and decreased inflammation. Among many other uses, it is sometimes recommended for brain health. Side effects are unexpected.