Does long-term creatine supplementation impair kidney function in resistance-trained individuals consuming a high-protein diet?

Background: the aim of this study was to determine the effects of creatine supplementation on kidney function in resistance-trained individuals ingesting a high-protein diet.methods: a randomized,double-blind,placebo-controlled trial was performed. the participants were randomly allocated to receive either creatine (20 g/d for 5 d followed by 5 g/d throughout the trial) or placebo for 12 weeks. all of the participants were engaged in resistance training and consumed a high-protein diet (i.e.,≥ 1.2 g/kg/d). subjects were assessed at baseline (pre) and after 12 weeks (post). glomerular filtration rate was measured by 51cr-edta clearance. additionally,blood samples and a 24-h urine collection were obtained for other kidney function assessments.results: no significant differences were observed for 51cr-edta clearance throughout the trial (creatine: pre 101.42 ± 13.11,post 108.78 ± 14.41 ml/min/1.73m2; placebo: pre 103.29 ± 17.64,post 106.68 ± 16.05 ml/min/1.73m2; group x time interaction: f = 0.21,p = 0.64). creatinine clearance,serum and urinary urea,electrolytes,proteinuria,and albuminuria remained virtually unchanged.conclusions: a 12-week creatine supplementation protocol did not affect kidney function in resistance-trained healthy individuals consuming a high-protein diet; thus reinforcing the safety of this dietary supplement.trial registration: clinicaltrials.gov nct01817673. © 2013 lugaresi et al.; licensee biomed central ltd.