HealthWise® is 100% pure pharmaceutical grade amino acid powder. L-Citrulline is an amino acid which is converted in the kidneys to L-Arginine and nitric oxide. Nitric oxide is well known for its function as a vasodilator. L-Citrulline also increases Ornithine and Arginine plasma content. Did you know? Citrulline is derived from the Latin word 'Citrullus' and was first isolated from watermelon in 1914.