Creatine and protein-rich diet combination not dangerous for kidneys
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.
Protein, creatine & 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."
J Int Soc Sports Nutr. 2013 May 16;10(1):26.
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