L-Citrulline is an amino acid produced by the body as a byproduct of synthesizing arginine, another amino acid. L-Citrulline and Nitric Oxide level is made possible by nitric oxide synthases, a class of enzymes that synthesize nitric oxide from L-arginine. L-arginine is a form of arginine. People use L-citrulline supplements for diabetes mellitus, Alzheimer’s disease, …