Creatine (which comes from the Greek word “kreas”, meaning “meat”) is a molecule that is produced in the body from the amino acids arginine, glycine, and methionine. It's primarily made in the liver and (to a lesser extent) in the kidneys and pancreas.[1][2] Creatine stores high-energy phosphate groups in the form of phosphocreatine. These phosphate groups are donated to ADP to regenerate it to ATP, the primary energy carrier in the body.[3] Creatine’s role in energy production is particularly relevant under conditions of high energy demand, such as intense physical or mental activity.
Creatine can be found in some animal-based foods and is most prevalent in meat and fish.[4][5] Athletes commonly take it as a powder or in capsules.