Effects of Long-term Creatine Supplementation

Title: Effects of Long-term Creatine Supplementation on Liver and Kidney Functions in American College Football Players.

Researchers: Mayhew DL, Mayhew JL, Ware JS

Institution: Exercise Science Program at Truman State University, Kirksville, MO 63501 and the Athletic Department at Truman State University, Kirksville, MO.

Summary: The purpose of this study was to determine the effect of long-term Cr supplementation on blood parameters reflecting liver and kidney function.

Methods: Twenty-three members of an NCAA Division II American football team (ages = 19-24 years) with at least 2 years of strength training experience were divided into a Cr monohydrate group (CrM, n = 10) in which they voluntarily and spontaneously ingested creatine, and a control group (n = 13) in which they took no supplements. Individuals in the CrM group averaged regular daily consumption of 5 to 20g for 0.25 to 5.6 years. Venous blood analysis for serum albumin, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, bilirubin, urea, and creatinine produced no significant differences between groups.

Results: Creatinine clearance was estimated from serum creatinine and was not significantly different between groups. Within the CrM group, correlations between all blood parameters and either daily dosage or duration of supplementation were nonsignificant.

Conclusion: Oral supplementation with CrM has no long-term detrimental effects on kidney or liver functions in highly trained college athletes in the absence of other nutritional supplements.

Discussion: Questions about creatine's safety are probably the most frequently brought up by people who don't like (and usually don't understand) supplements. This study by Mayhew and colleagues is a welcome addition to the already growing body of creatine safety research. (1,2,3,4,5,6,7)

The following by Bryan Hancock HST
Most questions revolve around the effects of creatine supplementation on the liver and kidney. These are the two organs are involved in "processing" creatine once it is ingested. The Liver breaks it down and the kidneys excrete it. From this study, and others before it, we see that long term supplementation with creatine in doses usually taken by bodybuilders (5-20 grams) for extended periods of time do not lead to dysfunction of either organ, nor does it cause abnormalities in the indicators of liver and kidney function.

Considering that fact that creatine supplementation has been shown to enhance anaerobic exercise performance by increasing power output (8), muscular strength and work (9,10,11), and muscle fiber size (12), and to top it off, completely safe even with long term supplementation, its no wonder this is one of my first tier recommendation for effective and safe supplements for putting on muscle size.

Additional References:

1: Poortmans JR, Auquier H, Renaut V, Durussel A, Saugy M, Brisson GR. Effect of short-term creatine supplementation on renal responses in men. Eur J Appl Physiol Occup Physiol. 1997;76(6):566-7.

2: Poortmans JR, Francaux M. Long-term oral creatine supplementation does not impair renal function in healthy athletes. Med Sci Sports Exerc. 1999 Aug;31(8):1108-10.

3: Terjung RL, Clarkson P, Eichner ER, Greenhaff PL, Hespel PJ, Israel RG, Kraemer WJ, Meyer RA, Spriet LL, Tarnopolsky MA, Wagenmakers AJ, Williams MH. American College of Sports Medicine roundtable. The physiological and health effects of oral creatine supplementation. Med Sci Sports Exerc. 2000 Mar;32(3):706-17.

4: Robinson TM, Sewell DA, Casey A, Steenge G, Greenhaff PL. Dietary creatine supplementation does not affect some haematological indices, or indices of muscle damage and hepatic and renal function. Br J Sports Med. 2000 Aug;34(4):284-8.

5: Poortmans JR, Francaux M. Adverse effects of creatine supplementation: fact or fiction? Sports Med. 2000 Sep;30(3):155-70.

6: Schilling BK, Stone MH, Utter A, Kearney JT, Johnson M, Coglianese R, Smith L, O'Bryant HS, Fry AC, Starks M, Keith R, Stone ME. Creatine supplementation and health variables: a retrospective study. Med Sci Sports Exerc. 2001 Feb;33(2):183-8.

7: Benzi G, Ceci A. Creatine as nutritional supplementation and medicinal product. J Sports Med Phys Fitness. 2001 Mar;41(1):1-10.

8: Earnest CP, Snell PG, Rodriguez R, Almada AL and Mitchell TL (1995) The effect of creatine monohydrate ingestion on anaerobic power indices, muscular strength and body composition. Acta Physiol Scand 153: 207-209

9: Casey A, Constantin-Teodosiu D, Howell S, Hultman E and Greenhaff PL (1996) Creatine ingestion favorably affects performance and muscle metabolism during maximal exercise in humans. Am J Physiol 271: E31-E37

10: Vandenberghe K, Goris M, Van Hecke P, Van Leemputte M, Vangerven L and Hespel P (1997) Long-term creatine intake is beneficial to muscle performance during resistance training. J Appl Physiol 83: 2055-2063

11: Volek JS, Duncan ND, Mazzetti SA, Staron RS, Putukian M, Gomez AL, Pearson DR, Fink WJ and Kraemer WJ (1999) Performance and muscle fiber adaptations to creatine supplementation and heavy resistance training. Med Sci Sports Exerc 31: 1147-1156

12: Volek JS, Duncan ND, Mazzetti SA, Staron RS, Putukian M, Gomez AL, Pearson DR, Fink WJ and Kraemer WJ (1999) Performance and muscle fiber adaptations to creatine supplementation and heavy resistance training. Med Sci Sports Exerc 31: 1147-1156