Popular with active individuals, NOW Foods Arginine & Ornithine is an amino acid supplement that supports protein metabolism. Arginine is an important factor in the urea cycle, a metabolic process that detoxifies and cleanses the body of excess nitrogen. Ornithine is a precursor to citrulline, proline and glutamic acid, which help boost blood flow, support metabolism and more important functions throughout the body. Each 2-capsule serving delivers 1 g L-arginine and 500 mg L-ornithine.