Creatine

Derived from amino acids, creatine is a naturally occurring compound that plays a key role in the body’s ability to produce energy. Roughly 95% of the body’s creatine is stored in skeletal muscle tissue, with a higher concentration in fast-twitch, type II muscle fibers. Within the muscles, creatine exists in two main forms—approximately two-thirds are stored as phosphocreatine (PCr), while the remaining one-third remains as free creatine. PCr serves as a rapid energy reserve, helping regenerate adenosine triphosphate (ATP) especially during bursts of physical activity. Creatine is produced endogenously at an amount of about 1 g per day. Synthesis predominately occurs in the liver, kidneys, and to a lesser extent, the pancreas. The remainder of the creatine available to the body is obtained through the diet at about 1 g per day in an omnivore diet. Dietary sources of creatine include animal-based proteins, notably red meat and fish. Approximately 1–2% of intramuscular creatine is broken down and excreted through the urine each day. Supplemental creatine has been shown to enhance athletic performance and recovery, promote longevity and healthy aging, and support optimal cognitive function.