L-arginine is an amino acid that helps the body build protein. Your body usually makes all the L-arginine it needs. L-arginine is also found in most protein-rich foods, including fish, red meat, poultry, soy, whole grains, beans and dairy products. As a supplement, L-arginine can be used orally and topically.

L-arginine is one of many amino acids the body needs to function properly. Like other amino acids, L-arginine plays a role in building protein. The body uses protein to help build muscle and rebuild tissue.

Overall, research has shown that L-arginine is safe and generally well tolerated when taken in supplement form, even when taken daily over long periods of 1 year or more.

Research studies confirm that men who take L-arginine consistently for two to six months benefit from markedly increased testosterone levels.