creatine

Creatine is a nitrogenous organic acid that occurs naturally in vertebrate tissue and acts as a key energy buffer for high‑intensity, short‑duration activities. In the body, it is synthesized primarily in the liver, kidneys, and pancreas from the amino acids glycine, arginine, and methionine, and is also obtained from dietary meat and fish. The majority of body creatine is stored in skeletal muscle as phosphocreatine, which donates a phosphate group to adenosine diphosphate to rapidly regenerate adenosine triphosphate during short bursts of high‑intensity effort. Creatine is also present in smaller amounts in brain and other tissues, where it may support cellular energy metabolism.

Endogenous production and diet provide most of the daily creatine supply; muscle stores can be replenished by supplements. Creatine monohydrate is the most studied and cost‑effective form; other formulations exist but do not consistently outperform monohydrate. Typical supplementation protocols include a loading phase of about 20 g per day (divided into 4 doses) for 5–7 days, followed by a maintenance dose of 3–5 g per day; an alternative approach is 0.3 g/kg per day for 5–7 days, then 3–5 g per day. Taking creatine with carbohydrates or after exercise can enhance uptake into muscle.

In athletes, creatine supplementation has been shown to improve performance in short, high‑intensity activities, increase strength and lean mass when combined with resistance training, and may aid recovery. Vegetarians often exhibit larger baseline stores and greater gains with supplementation. Safety in healthy individuals is generally good; common concerns include weight gain from water retention and, rarely, gastrointestinal upset. People with kidney disease should use caution and consult a clinician, as should anyone with concerns about potential interactions; creatine is not a prohibited substance in major sports bodies.