L-Arginine is featured in nobel-prize winning author Dr. Louis Ignarro's book on improving heart health without drugs, entitled NO More Heart Disease. It is considered a semi-essential amino acid and is thought of as one of the bodybuilding amino acids because the body uses it to release growth hormone.* Human growth hormone is used by the body to build muscle strength and tone and to enhance the burning of fats. L-arginine is important in the urea cycle for the metabolism of ammonia produced in the breakdown of protein.* L-arginine also stimulates the production of nitric oxide which supports vasodilation.* Other amino acids in the urea cycle are L-Citrulline and L-Ornithine.* Hypoallergenic.