Kinetics of creatine ingested as a food ingredient
- 425 Downloads
The aim of the present study was to test if the consumption of creatine incorporated in food bars modifies creatine plasma kinetics, erythrocyte retention and loss in urine and in feces when compared with its consumption in the form of an aqueous solution (AS). Seventeen healthy young men ingested 2 g creatine either in the form of AS, or incorporated in a protein (PP)- or in a beta-glucan (BG)-rich food bar. Kinetics of plasma creatine was measured for 8-h duration and urinary excretion for 24 h. Then, the subjects received the same treatment thrice a day for 1 week at the end of which creatine contents were determined in erythrocytes and in feces (n = 4 for feces). The three crossover treatments were interspaced by a 40 ± 1.2-day wash-out. Absorption of creatine was slowed down by 8-fold in the presence of BG (P < 0.001) and by 4-fold with PP (P < 0.001) whereas the velocity rate constant of elimination and the area under the curve were not modified. Urinary loss of creatine in the first 24 h following ingestion was 15 ± 1.9% in AS and 14 ± 2.2% in PP conditions (NS), whereas it was only 8 ± 1.2% with BG (P = 0.004). Increase in creatine concentration in erythrocyte was similar in whatever form the creatine was ingested. Creatine seems to be totally absorbed since no creatine or creatinine was detectable in feces. No side effects were reported. In conclusion, ingestion of creatine combined with BG facilitates its retention by slowing down its absorption rate and reducing its urinary excretion.
KeywordsCreatinine Erythrocytes Feces Pharmacokinetics Beta-glucan
The authors are indebted to Francine Loupe-Reding and Vinciane Godaert for their technical assistance, Dominik Grathwohl for his assistance in the statistical treatment of the data and Antoine Audrin, Aylin Harzadin and Jean-Jacques Desjardins for recipes and manufacture of the test bars.
- Chanutin A (1926) The fate of creatine when administered to man. J Biol Chem: 29–41Google Scholar
- Folin O (1906) Hammarsten’s Festschrift. iii: 1Google Scholar
- Francaux M, Poortmans JR (2006) Side sffects of creatine supplementation in athletes. Int J Sports Physiol Perf 1:309–321Google Scholar
- Harris RC, Soderlund K, Hultman E (1992) Elevation of creatine in resting and exercised muscle of normal subjects by creatine supplementation. Clin Sci (Lond) 83:367–374Google Scholar
- Hespel P, Op’t Eijnde B, Van Leemputte M, Urso B, Greenhaff PL, Labarque V, Dymarkowski S, Van Hecke P, Richter EA (2001) Oral creatine supplementation facilitates the rehabilitation of disuse atrophy and alters the expression of muscle myogenic factors in humans. J Physiol 536:625–633PubMedCrossRefGoogle Scholar
- Poortmans JR, Francaux M (2002) Renal implications of exogenous creatine monohydrate supplementation. Am J Med Sports 4:212–216Google Scholar
- Poortmans JR, Francaux M (2007) Creatine consumption in health. In: JR Stout (ed) Essentials of creatine in sports (in press)Google Scholar
- Siedel J, Mollering H, Ziegenhorn J (1984) Sensitive color reagent for the enzymatic determination of creatinine. Clin Chem 30:968Google Scholar
- Terjung RL, Clarkson P, Eichner ER, Greenhaff PL, Hespel PJ, Israel RG, Kraemer WJ, Meyer RA, Spriet LL, Tarnopolsky MA, Wagenmakers AJ, Williams MH (2000) American College of Sports Medicine roundtable. The physiological and health effects of oral creatine supplementation. Med Sci Sports Exerc 32:706–717PubMedCrossRefGoogle Scholar