Taurine is one of the most abundant free amino acids in the body. In the diet, taurine is found in meat and fish, but not in plant foods. Taurine is regarded as a conditionally essential amino acid, because it can be synthesized by the body from the other sulfur-containing amino acids cysteine and methionine. Taurine synthesis is vitamin B6-dependent. It is not incorporated into proteins, but taurine is very important in metabolism and is present in particularly high levels in the brain, skeletal muscle, heart, and retina of the eye. Taurine is essential for infants, as it plays important roles in the development of the nervous system, retina, and muscle tissue. Taurine is well known for its role in bile salt synthesis and has crucial functions in the liver’s detoxification pathways. Taurine also appears to have a stabilizing effect on cell membranes and is important in maintaining normal extra- and intracellular distribution of calcium. This, in turn, has implications on neuronal excitability and the regulation of osmotic pressure. In the retina, taurine helps maintain the structure and function of the visual cells.