Risk assessment of the potential side effects of long-term creatine supplementation in team sport athletes.

BACKGROUND Use of creatine has become widespread among sportsmen and women, although there are no conclusive evidences concerning possible health risks of long-term creatine supplementation. THE AIM OF THE STUDY To investigate long-term effects of creatine monohydrate supplementation on clinical parameters related to health. METHODS Eighteen professional basketball players of the first Spanish Basketball League participated in the present longitudinal study. The subjects were ingesting 5 g creatine monohydrate daily during three competition seasons. Blood was collected in the morning after an overnight fast, five times during each of the three official competition seasons of the first National Basketball League (September 1999-June 2000, September 2000-June 2001 and September 2001-June 2002) and the European League. Standard clinical examination was performed for 16 blood chemistries. RESULTS The plasma concentrations of all clinical parameters did not alter significantly during the analyzed time frames of creatine supplementation. All of these parameters were, with the exception of creatinine and creatine kinase, within their respective clinical ranges at all time points. CONCLUSION Our data shows that low-dose supplementation with creatine monohydrate did not produce laboratory abnormalities for the majority of the parameters tested.