Creatine is an amino acid derivative. It is transformed in the muscle into phosphocreatine. Phosphocreatine regenerates ATP (Adenosine TriPhosphate), a molecule that provides energy to our cells. It is for this reason that creatine is used by sportsmen and women who wish to increase their muscle mass.
Creatine requirements are between 1.5 and 3g per day. It is found in beef and fish in particular. Creatine intakes are lower in people on a vegetarian diet.