(Science: amino acid) Is made from the amino acid arginine and in turn is a precursor to form glutamic acid, citruline and proline. Ornithine's chief therapeutic value lies in its involvement in the urea cycle and its ability to enhance liver function, protect the liver and detoxify harmful substances. It has been used in the treatment of hepatic coma states. It also helps release a growth hormone that metabolises excess body fat when combined with arginine. This growth hormone is also an immune stimulant. In animal studies arginine and ornithine have improved immune responses to bacteria, viruses and tumour cells.