L-Arginine is an essential amino acid necessary to promote lean muscle mass, immune system function, detoxifies amino, and liver detoxification with added Ornitine.* Twinlab L-Arginine & L-Ornithine Free from Amino Acids. Twinlab L-Arginine & L-Ornithine Capsules are easier to swallow and assimilate. Well tolerated by most highly allergic individuals. This product is manufactured at a state of the art facility.