NOW - L-Arginine 500mg - 250 Capsule(s) - NPN: 80006111 -- L-arginine is a chemical building block called "an amino acid." It is obtained from the diet and is necessary for the body to make proteins. L-arginine is found in red meat, poultry, fish, and dairy products. It can also be made in a laboratory and used as medicine.L-arginine is used for chest pain (angina), narrowing of blood vessels that causes poor blood flow to the limbs (peripheral arterial disease), high blood pressure, erectile dysfunction (ED), a pregnancy complication marked by high blood pressure and protein in the urine (pre-eclampsia), high blood pressure during pregnancy, and a serious intestinal disease in premature infants (necrotizing enterocolitis or NEC). It is also used for many other conditions, but there is no good scientific evidence to support these other uses.How does it work?L-arginine is converted in the body into a chemical called nitric oxide. Nitric oxide causes blood vessels to open wider for improved blood flow. L-arginine also stimulates the release of growth hormone, insulin, and other substances in the body.