Taurine: an essential amino sulfonic acid for retinal health.

Taurine (2-amino-ethanesulfonic acid) is a naturally occurring amino sulfonic acid derived from cysteine and methionine metabolism. Its common name derives from the ox, as it was first isolated from the bile of an ox (Froger et al., 2014). The molecular structure of taurine differs from that of amino acids by the presence of a sulfonic acid, instead of the more common carboxylic acid group in the structure of amino acids. Despite this, taurine is considered a non-essential amino acid because it can be synthesized endogenously in the liver of most mammals. However, the endogenous synthesis of taurine is insufficient to supply the needs and most of it is obtained through diet.