Background: 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 assess the impact of Cre supplementation on kidney function based on data from randomized controlled trials (RCTs). Methods: A systematic literature search was conducted in PubMed, Cochrane Library, Scopus, and clinicaltrials.gov 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 separately for each primary outcome, based on supplementation duration and participant physical training status. Results: A total of 19 RCTs and one double-blind randomized crossover study were included in the meta-analysis. Cre supplementation was associated with an increase in serum Crn (MD = 0.69 mg/dL, 95% CI: 0.38 to 1.00, n=19). There was no difference between the two groups nor in the urea concentrations (MD = -0.05 mg/dL; 95% CI: -0.24 to 0.15, n=12), neither in eGFR values (MD = -0.21 mL/min/1.73 m²; 95% CI: -0.65 to 0.22, n=8). No differences were observed between the 1-month supplementation subgroups with respect to serum Crn (p = 0.19), serum urea (p = 0.33), or eGFR (p = 1.0). Conclusions: Cre supplementation seems to relate to an increase on serum Crn, but this is not related to significant alterations on urea concentrations and eGFR. Further long-term RCTs, extending beyond one year, are needed to assess its safety in terms of renal function.
Ανδρέας Κ. Τσιάρας (Wed,) studied this question.