Creatine supplements

Creatine supplements are dietary supplements marketed as increasing high-intensity athletic performance.

Uses

There is scientific evidence that short term creatine use can increase maximum power and performance in high-intensity anaerobic repetitive work (periods of work and rest) by 5 to 15%.^[1] Studies in endurance athletes have been less than promising, most likely because these activities are sustained at a given intensity and thus do not allow for significant intra-exercise synthesis of additional creatine phosphate molecules. Ingesting creatine can increase the level of phosphocreatine in the muscles up to 20%. Creatine has no significant effect on aerobic endurance, though it will increase power during short sessions of high-intensity aerobic exercise.^[2][3]

Creatine use is not considered doping and is not banned by the majority of sport-governing bodies. However, in the United States, the NCAA recently ruled that colleges could not provide creatine supplements to their players, though the players are still allowed to obtain and use creatine independently.^[4]

Side effects

Side effects include:

• Weight gain due to extra water retention to the muscle
• Potential muscle cramps / strains / pulls
• Upset stomach
• Diarrhea
• Dizziness
• High blood pressure due to extra water consumption

In 2004 the European Food Safety Authority (EFSA) published a record that stated that oral long-term intake of 3 g pure creatine per day is "unlikely to pose any risk".^[5] The reports of damage to the kidneys or liver by creatine supplementation have been scientifically refuted.^[6]

Both the American Academy of Pediatrics and the American College of Sports Medicine recommend that individuals younger than 18 years old not use creatine.^[7][8]

People with kidney disease, high blood pressure, or liver disease should not take creatine as a dietary supplement. Being a dietary supplement, it is advised that creatine should be taken under the supervision of a health professional.^[9][10]

Drug interactions

Creatine taken with medications that can harm the kidney can increase the risk of kidney damage. It is advised to speak with your doctor or pharmacist before taking creatine if you are on these type of medications.^[9][10]

• Non-steroidal anti-inflammatory drugs (NSAIDs) - some examples are ibuprofen (Motrin, Advil) and naproxen (Aleve)
• Diuretics (water pills) - An example is furosemide (Lasix)
• Cimetidine (Tagamet)
• Probenicid

Pharmacology

This graph shows the mean plasma creatine concentration (measured in μmol/L) over an 8 hour period following ingestion of 4.4 grams of creatine in the form of creatine monohydrate (CrM), tri-creatine citrate (CrC), or creatine pyruvate (CrPyr).^[11]

Endogenous serum or plasma creatine concentrations in healthy adults are normally in a range of 2–12 mg/L. A single 5 g (5000 mg) oral dose in healthy adults results in a peak plasma creatine level of approximately 120 mg/L at 1–2 hours post-ingestion. Creatine has a fairly short elimination half-life, averaging just less than 3 hours, so to maintain an elevated blood plasma level it would be necessary to take small oral doses every 3–6 hours throughout the day. Creatine is consumed by the body fairly quickly, and if one wishes to maintain the high concentration of creatine, 2-5 g daily is the standard amount to intake.^[12][13][14]

Creatine supplementation appears to increase the number of myonuclei that satellite cells will 'donate' to damaged muscle fibers, which increases the potential for growth of those fibers. This increase in myonuclei probably stems from creatine's ability to increase levels of the myogenic transcription factor MRF4.^[15]

Chemistry

Creatine ethyl ester

CEE is a form of commercially available creatine touted to have higher absorption rates and a longer serum half-life than regular creatine monohydrate by several supplement companies. However, no peer-reviewed studies have emerged on creatine ethyl ester which conclusively prove these claims. A study presented at the 4th International Society of Sports Nutrition (ISSN) annual meeting demonstrated that the addition of the ethyl group to creatine actually reduces acid stability and accelerates its breakdown to creatinine. The researchers concluded that creatine ethyl ester is inferior to creatine monohydrate as a source of creatine.^[16]

As a supplement, the compound was patented, and licensed through UNeMed, the technology transfer entity of the University of Nebraska Medical Center.^[17]

Creatine nitrate

Creatine nitrate is a nitrate salt form of creatine. No benefits have been noted except that it may be more water-soluble.^[18]

Creatine gluconate

Creatine gluconate is a form of creatine where the molecule is bound to gluconic acid.^[19]

History

In 1912, Harvard University researchers Otto Folin and Willey Glover Denis found evidence that ingesting creatine can dramatically boost the creatine content of the muscle.^[20] In the late 1920s, after finding that the intramuscular stores of creatine can be increased by ingesting creatine in larger than normal amounts, scientists discovered creatine phosphate, and determined that creatine is a key player in the metabolism of skeletal muscle. The substance creatine is naturally formed in vertebrates.

While creatine's influence on physical performance has been well documented since the early twentieth century, it came into public view following the 1992 Olympics in Barcelona. An August 7, 1992 article in The Times reported that Linford Christie, the gold medal winner at 100 meters, had used creatine before the Olympics. An article in Bodybuilding Monthly named Sally Gunnell, who was the gold medalist in the 400-meter hurdles, as another creatine user. In addition, The Times also noted that 100 meter hurdler Colin Jackson began taking creatine before the Olympics.^[21][22]

At the time, low-potency creatine supplements were available in Britain, but creatine supplements designed for strength enhancement were not commercially available until 1993 when a company called Experimental and Applied Sciences (EAS) introduced the compound to the sports nutrition market under the name Phosphagen.^[23] Research performed thereafter demonstrated that the consumption of high glycemic carbohydrates in conjunction with creatine increases creatine muscle stores.^[24] In 1998, MuscleTech Research and Development launched Cell-Tech, the first creatine-carbohydrate-alpha lipoic acid supplement.^[25]

References