Creatine is safe for soccer players

Creatine is one of the most popular sports supplements on the planet. It increases muscle mass, strength and performance in some high-intensity sports. Creatine has few known side effects. High doses (i.e. more than 20 grams per day) cause a sharp increase in formaldehyde levels in the blood, which can have toxic effects on the kidneys and the inner lining of blood vessels.

Carlos Ohanian and colleagues from the University of Uruguay found that soccer players who took creatine over a period of 56 days showed no changes in health markers in blood or urine. 14 soccer players were divided into either a creatine or a placebo group. The creatine group took 15 grams of creatine per day for seven days and 3 grams of creatine per day for the remaining 49 days. Only the creatine group gained weight during the study. Creatine kinase (a marker of muscle damage) and uric acid (a marker of amino acid metabolism) decreased in the creatine group, but these changes are probably more attributable to the training than the supplement.

Creatine appears to be safe for short-term use, but we need further detailed research into the long-term effectiveness and safety of this supplement.
(British Journal Sports Medicine, 42: 731-735, 2008)