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 most commonly used for recovery after surgery, a pregnancy complication marked by high blood pressure and protein in the urine (pre-eclampsia), and heart and blood vessel conditions, such as chest pain (angina) and high blood pressure. It is also used for many other conditions, but there is no good scientific evidence to support many of these uses.