Health assessment of creatine as a dietary supplement

Creatine is a substance occurring naturally in the, human body. The major p roportion of the total Creatine pool is found in skeletal muscle (circa 90 %), heart and brain. The total creatine content in a normal, healthy person of TO kg is approximately 120 g. Creatine and its phosphorylated form, pho spho-creatine, play an important role for cellular energy storage, bufferin g, and transport. Due to these properties, Creatine supplementation has bec ome very popular in sports among athletes to enhance muscle performance and muscle mass. For this purpose, Creatine is usually taken during a loading phase at 20 g per day for one week and during a maintenance phase at 5-10 g , per day during extended periods of training. According to numerous public ations, such a supplementation scheme is well tolerated and does not lead t o significant side effects. Occasionally slight gastrointestinal discomfort or muscle cramping were reported. in those reports where liver and kidney functions of healthy athletes were examined specifically, no indications fo r adverse effects of Creatine an these organs have been noticed. Systematic studies on the clinical toxicology of creatine, however, are not available at present. Since no reports about experimental toxicity studies have been published so far, a series of toxicological examinations was thus performe d, the results of which are reported within the scope of this publication. Based on these new data, Creatine did not reveal acute nor subacute toxic e ffects. The substance is well tolerated locally, as well. Furthermore, Crea tine does not act as a sensitizing agent. Finally, no mutagenic effects wer e observed with Creatine in standardized bacterial mutagenicity tests. Sinc e a significant proportion of the Creatine, taken at the dose levels mentio ned above, is immediately excreted via the kidneys and since there is no ev idence that very high dosages of Creatine are more beneficial, a loading do sage of 10 g per day for the first 8 days, to fill-up endogenous creatine p ools, and a maintenance dose of 4-5 g per day, during the time after, are t hus recommended. In addition, as a precautionary measure, it is advisable, after a prolonged period of Creatine intake (e.g. during 3 months), to take a break for several weeks (e, g. 4 weeks which is the wash-out time to ret urn to original Creatine levels).