Creatine is an amino
acid located mostly in your body's muscles as well as in the brain. Most people
get creatine through seafood and red meat — though at levels far below those
found in synthetically made creatine supplements. The body's liver, pancreas
and kidneys also can make about 1 gram of creatine per day.
Your body stores
creatine as phosphocreatine primarily in your muscles, where it's used for
energy. As a result, people take creatine orally to improve athletic
performance and increase muscle mass.