Creatine (/ˈkriːətiːn/ or /ˈkriːətɪn/) is a nitrogenous organic acid that occurs naturally in vertebrates and helps to supply energy to all cells in the body, primarily muscle. This is achieved by increasing the formation of adenosine triphosphate (ATP). Creatine was identified in 1832 when Michel Eugène Chevreul discovered it as a component of skeletal muscle, which he later named after the Greek word for meat, κρέας (kreas). In solution, creatine is in equilibrium with creatinine.
Creatine supplements are used by athletes, bodybuilders, wrestlers, sprinters, and others who wish to gain muscle mass, typically consuming 2 to 3 times the amount that could be obtained from a very-high-protein diet. The Mayo Clinic states that creatine has been associated with asthmatic symptoms and warns against consumption by persons with known allergies to creatine.
Recent studies have discredited concerns that creatine supplementation could affect hydration status and heat tolerance and lead to muscle cramping and diarrhea.
There are reports of kidney damage with creatine use, such as interstitial nephritis; patients with kidney disease should avoid use of this supplement. In similar manner, liver function may be altered, and caution is advised in those with underlying liver disease, although studies have shown little or no adverse impact on kidney or liver function from oral creatine supplementation. In 2004 the European Food Safety Authority (EFSA) published a record which stated that oral long-term intake of 3g pure creatine per day is risk-free. The reports of damage to the kidneys by creatine supplementation have been scientifically refuted.
Long-term administration of large quantities of creatine is reported to increase the production of formaldehyde, which has the potential to cause serious unwanted side-effects. However, this risk is largely theoretical because urinary excretion of formaldehyde, even under heavy creatine supplementation, does not exceed normal limits.
Extensive research has shown that oral creatine supplementation at a rate of 5 to 20 grams per day appears to be very safe and largely devoid of adverse side-effects, while at the same time effectively improving the physiological response to resistance exercise, increasing the maximal force production of muscles in both men and women.
A meta analysis performed in 2008 found that creatine treatment resulted in no abnormal renal, hepatic, cardiac or muscle function.
While some research indicates that supplementation with pure creatine is safe, many commercially available supplements were found to contain toxic impurities including heavy metals and organic contaminants. A survey of 33 commercially available supplements found that over 50% of them exceeded the European Food Safety Authority recommendations in at least one contaminant.
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Properties |
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| Molecular formula | C4H9N3O2 |
| Molar mass | 131.13 g mol−1 |
| Appearance | White crystals |
| Odor | Odourless |
| Melting point | 255 °C; 491 °F; 528 K |
| Solubility in water | 13.3 g L−1 (at 18 °C) |
| log P | −1.258 |
| Acidity (pKa) | 3.429 |
| Basicity (pKb) | 10.568 |
| Isoelectric point | 8.47 |