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. I 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 L-Ornithine alpha-ketoglutarate or OKG which, under certain conditions, may have immunomodulatory and anticatabolic and/or anabolic actions. L-Ornithine may be very helpful if you are trying to lose fat. It is important because it initiates the release of growth hormone in the body. This can be very helpful with fat metabolism. The liver and immune system require L-Ornithine to function properly. It assists in ammonia detoxification and liver rejuvenation. L-Ornithine can also help with healing and repairing skin and tissue and is found in both these body parts. People recovering after surgery and athletes may also benefit from this nutrient.