Supplementation with creatine, you sometimes hear, is bad for your kidneys. Nevertheless, Brazilian researchers at the University of Sao Paulo demonstrated in 2008 that creatine had no negative effect on the kidney functioning of healthy test subjects aged between 18 and 35. A few weeks ago the Brazilians went a step further. They published a study which shows that the combination of creatine and protein supplementation isn’t dangerous for the kidneys.
In gyms you’ll find whole tribes of athletes who live on a protein rich diet and take creatine supplements as well. Although they are usually the picture of health, some nutritionists fear that the combination of protein and creatine supplementation is dangerous for the kidneys. The Brazilians have been trying for several years to work out whether the fear is grounded.
Besides the study we mentioned above, the Brazilians have published studies in which creatine supplementation had no effect on the kidney function of women in their late fifties [Appl Physiol Nutr Metab. 2011 Jun;36(3):419-22.] or on that of people with type 2 diabetes [Eur J Appl Physiol. 2011 May;111(5):749-56.]. They also published a case study in 2010 in which creatine supplementation in combination with a protein-rich diet had no effect on the kidney function of a 20-year-old man who had only one kidney. [Am J Kidney Dis. 2010 Mar;55(3):e7-9.]
In the most recently published study, the Brazilians used 26 males in their twenties as test subjects, all of whom did weight training. Their protein intake varied from 1.2 to 3.1 g per kg bodyweight per day.
Half of the men were given 20 g creatine per day for the first 5 days of the experiment. On the remaining days the men took 5 g creatine per day. The study lasted for a total of 12 weeks. The men in the control group were given a placebo.
Before and after the supplementation the researchers introduced a catheter with 51-chromium-ethylene tetra acetic acid [51-Cr-EDTA] into the bloodstream. They then monitored how quickly the substance disappeared out of the subjects’ blood. The faster that happens, the better the kidneys are working.
The combination of creatine and a protein-rich diet did not reduce kidney function. And when the researchers looked at the amount of protein, urea and electrolytes in the blood, they saw no effect either.
“It is possible that highly-trained athletes taking anabolic steroids and under exhaustive resistance training regimens may experience a differential response to creatine supplementation”, the researchers note.
“It is worth noting that all of the individuals were apparently healthy, so that these data cannot be extrapolated to individuals with, or at risk of, chronic kidney diseases. In such conditions, creatine users must be systematically monitored for kidney function.”
Does long-term creatine supplementation impair kidney function in resistance-trained individuals consuming a high-protein diet?
Lugaresi R, Leme M, de Salles Painelli V, Murai IH, Roschel H, Sapienza MT, Lancha Junior AH, Gualano B.
Source
School of Physical Education and Sport – Laboratory of Applied Nutrition and Metabolism, University of Sao Paulo, Av Mello de Moraes, 65, Sao Paulo, SP 05508-030, Brazil. gualano@usp.br.
Abstract
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.
PMID: 23680457 [PubMed] PMCID: PMC3661339
