title: Effect of oral creatine supplementation on urinary methylamine, formaldehyde, and formate.
abstract: OBJECTIVE
  It has been claimed that oral creatine supplementation might have potential cytotoxic effects on healthy consumers by increasing the production of methylamine and formaldehyde. Despite this allegation, there has been no scientific evidence obtained in humans to sustain or disprove such a detrimental effect of this widely used ergogenic substance.
  
  
  METHODS
  Twenty young healthy men ingested 21 g of creatine monohydrate daily for 14 consecutive days. Venous blood samples and 24-h urine were collected before and after the 14th day of supplementation. Creatine and creatinine were analyzed in plasma and urine, and methylamine, formaldehyde, and formate were determined in 24-h urine samples.
  
  
  RESULTS
  Oral creatine supplementation increased plasma creatine content 7.2-fold (P < 0.001) and urine output 141-fold (P < 0.001) with no effect on creatinine levels. Twenty-four-hour urine excretion of methylamine and formaldehyde increased, respectively, 9.2-fold (P = 0.001) and 4.5-fold (P = 0.002) after creatine feeding, with no increase in urinary albumin output (9.78 +/- 1.93 mg x 24 h(-1) before, 6.97 +/- 1.15 mg x 24 h(-1) creatine feeding).
  
  
  CONCLUSIONS
  This investigation shows that short-term, high-dose oral creatine supplementation enhances the excretion of potential cytotoxic compounds, but does not have any detrimental effects on kidney permeability. This provides indirect evidence of the absence of microangiopathy in renal glomeruli.
authors.affiliation: Higher Institute of Physical Education and Physical Therapy, Free University of Brussels, Brussels, Belgium. jrpoortm@ulb.ac.be
authors.forename: Jacques R
authors.initials: JR
authors.lastname: Poortmans
authors.forename: Alain
authors.initials: A
authors.lastname: Kumps
authors.forename: Pierre
authors.initials: P
authors.lastname: Duez
authors.forename: Aline
authors.initials: A
authors.lastname: Fofonka
authors.forename: Alain
authors.initials: A
authors.lastname: Carpentier
authors.forename: Marc
authors.initials: M
authors.lastname: Francaux
mesh_terms: D000284:Administration, Oral; D000328:Adult; D003401:Creatine / Q000008:administration & dosage / Q000494:pharmacology*; D003404:Creatinine / Q000097:blood / Q000652:urine; D019587:Dietary Supplements; D005557:Formaldehyde / Q000652:urine*; D005561:Formates / Q000652:urine*; D006801:Humans; D008297:Male; D008744:Methylamines / Q000652:urine*
chemical_list: D005561:Formates; D008744:Methylamines; C030544:formic acid; D005557:Formaldehyde; D003404:Creatinine; C027451:methylamine; D003401:Creatine