The effect of creatine supplementation on kidney function: a systematic review and meta-analysis of randomized...

Despite the widespread use of creatine (Cre) as a dietary supplement and its potential benefits, concerns have been raised about its possible adverse effects on kidney function. This systematic review and meta-analysis assesses the impact of Cre supplementation on kidney function based on data from randomized controlled trials (RCTs).

A systematic literature search was conducted to identify RCTs assessing the effects of Cre supplementation on kidney function. The primary outcomes were serum creatinine (Crn), urea, and estimated glomerular filtration rate (eGFR). A random-effects meta-analysis was performed, and subgroup analyses were conducted for each primary outcome, based on supplementation duration and participant physical status.

A total of 19 RCTs and one double-blind randomized crossover study were included. Cre supplementation was associated with an increase in serum Crn (MD = 0.13 mg/dL, 95% CI: 0.07 to 0.18, n=19). There was neither a difference in urea concentrations (MD = -0.60 mg/dL; 95% CI: -2.15 to 0.96, n=12), nor in eGFR values (MD = -5.20 mL/min/1.73 m²; 95% CI: -15.00 to 4.60, n=8) between the two groups. No differences were observed between the <1-month and >1-month supplementation subgroups regarding serum Crn (p = 0.15), serum urea (p = 0.15), or eGFR (p = 0.88).

Cre supplementation seems to relate to an increase in serum Crn, but this is not related to significant alterations in urea concentrations and eGFR. Further long-term RCTs, extending beyond one year, are needed to assess its safety in terms of renal function.