L-ornithine is a basic amino acid and is important in the formation of urea. It is a nonprotein amino acid which means that it does not occur in proteins. The body uses it in the biosynthesis of L-arginine, L-proline and polyamines. L-ornithine is sometimes used as a nutritional supplement for its putative anabolic activity, even though there is little evidence to support this. However, there is a derivative of L-ornithine called ornithine alpha-ketoglutarate or OKG which, under certain conditions, may have immunomodulatory and anticatabolic and/or anabolic actions.
