Cystine and Cysteine

Cystine is a (non-essential) amino acid. It is one of a group of amino acids known as 'sulphur' amino acids. It comprises 2 molecules of Cysteine (another amino acid), held together by a strong chemical bond.

 

Cysteine is the more active and useful form of these of amino acids, being a necessary component of various proteins within the body (including Glutathione), but is easily damaged when consumed in its reduced state. For this reason the preferred nutritional form is Cystine, which the body can break down into Cysteine as required once digested.