Astaxanthin is used to treat alzheimer's disease, Parkinson's disease, stroke, high cholesterol, liver disease, age-related macular degeneration (age-related vision loss) and prevent cancer. It is also used for metabolic syndrome, a group of diseases that increase the risk of heart disease, stroke and diabetes. It can also be used to improve athletic performance, reduce post-workout muscle damage, and reduce post-workout muscle soreness. In addition, astaxanthin is taken orally to prevent sunburn, improve sleep, as well as carpal tunnel syndrome, indigestion, male infertility, menopausal symptoms and rheumatoid arthritis.