Three amino acids, arginine, glycine, and methionine, make creatine in the body. Creatine is transformed to phosphocreatine (PCr) when the amino acids are mixed, providing an instant energy supply during high-intensity explosive exercise. Creatine comprises amino acids typically present in animal products like meat and fish. If you eat a vegetarian or vegan diet, you may be deficient in certain amino acids and thus deficient in creatine, necessitating supplementation.
Supplementing creatine may benefit high-intensity sports like rugby, football, or weightlifting.