Creatine is a nitrogenous organic acid produced in the liver that helps supply energy to cells all over the body - particularly muscle cells. It is made out of three amino acids: L-arginine, glycine, and L-methionine.
Creatine is transported through the blood by an active transport system, it is then used by muscles that have high energy demands, such as the brain and skeletal muscle. In fact, around 95 percent of creatine in the human body is stored in skeletal muscle.