Puritan's Pride, L-Arginine, 1000 mg, 200 CapletsProduct Description Source of cellular energy in the body* Supports the effect of exercise* Arginine is one of 20 amino acids, the building blocks of protein.* Arginine can serve as a source of cellular energy, and is involved in various pathways throughout the body.* Arginine supports the effect of exercise and is one of the most important amino acids involved in immune function.* Product Benefits Ingredients Supplement Facts Serving Size: 1 Caplet