Effects of Creatine Supplementation on Renal Function

Creatine (CR) supplementation is commonly used by athletes. However, its effects on renal function remain controversial. Purpose: The aim of this study was to evaluate the effects of creatine supplementation on renal function and oxidative stress in healthy sedentary males (18-35 years old) submitted to exercise training. Methods: Subjects (n = 18) were randomly divided in two groups and were allocated to receive treatment with either creatine (CR) (~10g • day-1 over three months) or placebo (PL) (dextrose). All subjects undertook moderate intensity aerobic training, in three 40-minute sessions per week, during 3 months. Serum creatinine, TBARS, serum and urinary sodium and potassium were determined at baseline and at the study endpoint. Furthermore, cystatin C was also assessed prior to training (PRE), after 4 (POST 4) and 12 weeks (POST 12). Results: There were decreased in both oxidative stress (evaluated by TBARS - µM/24 h) (PRE CR: 8.2  4.4; PL: 6.4  0.8 vs. POST 12 CR: 2.5  1.8; PL: 2.1  1.6, p=0.0001) and cystatin C levels (mg/L) (PRE CR:0.82  0.09; PL: 0.88  0.07 vs. POST 12 CR: 0.71  0.06; PL: 0.75  0.09, p=0.0001) over the time, suggesting an increase in glomerular filtration rate. There were no significant differences between groups in other renal parameters investigated. Conclusions: These data indicate that high-dose creatine supplementation throughout three months does not provoke renal dysfunction in sedentary healthy males urdergoing aerobic training. Moreover, our results suggest that moderate aerobic training per se could improve renal function.