Ornithine is an amino acid that does not occur in proteins but is important in the formation of urea. L-Ornithine is a nonprotein amino acid. It is used in the body in the biosynthesis of L-arginine, L-proline and polyamines.

L-Ornithine is a basic amino acid, positively charged at physiological pH. It is also known as alpha,delta-diaminovaleric acid and 2,5-diaminopentanoic acid. Its molecular formula is C5H12N2O2, and its molecular weight is 132.16 daltons.

L-Ornithine is used as a nutritional supplement principally for its putative anabolic activity. There is little evidence to support this use. However, a derivative of L-ornithine called ornithine alpha-ketoglutarate or OKG may, under certain conditions, have immunomodulatory and anticatabolic and/or anabolic actions.

Ornithine is important because it induces the release of growth hormone in the body, which in turn helps with fat metabolism. Ornithine is required for a properly functioning immune system and liver. It assists in ammonia detoxification and liver Rejuvenation. Ornithine helps healing and repairing skin and tissue and is found in both these body parts. Unsupported claims that ornithine promotes muscle building, but this has not been proven. Ornithine is helpful for people recouping after surgery and athletes may benefit from this nutrient

L-Ornithine can be changed into L-Arginine in the body and it functions similarly in growth hormone release.