L-arginine is an amino acid that is naturally found in red meats, poultry, fish, and dairy products. It is necessary for protein production and is commonly used for circulation.

L-arginine is converted in the body into a chemical called nitric oxide. Nitric oxide causes blood vessels to open wider to improve blood flow. L-arginine also stimulates the release of growth hormone, insulin, and other substances in the body. It can be made in a laboratory and used in supplements.

People use L-arginine for chest pain and various circulation problems, erectile dysfunction, high blood pressure during pregnancy, and a serious disease in premature babies called necrotizing enterocolitis (NEC). It is also used for many other conditions, but there is not good scientific evidence to support these other uses.