Taurine is essential for cardiovascular function, and development and function of skeletal muscle, the retina, and the central nervous system. Taurine is an organic compound that accounts for up to 0.1% of total human body weight. Taurine has many fundamental biological roles, such as conjugation of bile acids, antioxidation, osmoregulation, membrane stabilization, and modulation of calcium signaling. It is essential for cardiovascular function, and development and function of skeletal muscle, the retina, and the central nervous system. Taurine is unusual among biological molecules in being a sulfonic acid, while the vast majority of biologically occurring acids contain the more weakly acidic carboxyl group. Taurine is sometimes called an amino acid, and indeed is an acid containing an amino group.