Creatine, or creatine monohydrate [NH₂-C(NH)-NCH₂(COOH)-CH₃], is a naturally occurring compound that helps to supply energy to the muscle cells.

Typically, half of the creatine (Cr) in our body comes from the food we eat (mainly from meat and fish), while the other half is synthesized from certain amino acids (glycine, arginine) in the liver, pancreas and kidneys. 95% is stored in the skeletal muscles, the rest in the brain, heart and testes.

In the muscles, a fraction of the total creatine binds to phosphate. The reaction is catalysed by creatine kinase, and the result is phosphocreatine (PCr). Phosphocreatine binds with adenosine diphosphate to convert it back to ATP (adenosine triphosphate), an important cellular energy source.

There is scientific evidence that taking creatine supplements can increase an athlete's performance in high-intensity anaerobic exercise. Ingesting creatine can increase the level of phosphocreatine in the muscles up to 20%. An additional study, published in August 2003 in the Royal Watson Society journal Proceedings, suggests increased mental capabilities as a result of oral intake of creatine over a 60 day period.

The marketing claims that creatine supplements also help to build muscle mass, however, are questionable. Athletes who take creatine do gain weight, but most of this weight gain is not muscle, but water (creatine takes water with it to the muscle cells). Also, creatine has no effect on aerobic exercise.

Creatine can cause dehydration due to increased absorption of water by the skeletal muscles. It is therefore not recommended for people with kidney disease. Current studies indicate that short-term creatine supplementation is safe, but the effects of long-term supplementation are still unknown.

Creatine is not considered doping and is currently acceptable to all sports-governing bodies.

External links

• Quackwatch on creatine (http://www.quackwatch.org/01QuackeryRelatedTopics/DSH/creatine.html)
• BBC News - Creatine 'boosts brain power' (http://news.bbc.co.uk/2/hi/health/3145223.stm)
• Science Blog - Creatine does affect metabolism (http://scienceblog.com/community/article3768.html)