It has been brought to my attention by a colleague that creatine supplementation over long periods can cause adverse affects on the liver. Is this true? Do you need to cycle the use of creatine to minimize adverse affects?
This is a common question among strength athletes who supplement using various nutritional strategies, as there are claims that creatine supplementation (CrS) may have a potential effect on health indices such as liver and kidney function, which is suggested on the basis of changes in clinical markers (blood chemistries) or case reports. As such, several studies have attempted to determine the validity of these anecdotally reported concerns during both short-term (five days to 12 weeks) and long term (up to five years) CrS.
Research published in the journal British Journal of Sports Medicine reported no adverse effects of acute or more chronic creatine supplementation on indices of hepatic, muscle and renal function. A group of 48 athletes were studied using CrS protocols ranging from five days (20 g/d) to nine weeks (3 g/d). All hepatic function induces were within the normal range at all times. The authors concluded that that there is no obvious risk to health of CrS at the recommended doses. In agreement, a well-controlled study published in the Journal of Exercise Physiologyonline examined hepatic stress following a loading phase of 0.3 g•kg-1•d-1 and a maintenance phase of 0.03 g•kg-1•d-1 for five weeks. A complete battery of blood chemistries used clinically in diagnosing hepatic dysfunction showed very little deviation from normal ranges. Such data strengthens the argument that CrS does not cause adverse effects for hepatic function in trained athletes.
Investigating the effects of long-term CrS, researchers from Truman State University examined blood parameters reflecting liver and kidney function in 23 members of an NCAA Division II American football team. Subjects were divided into a creatine group averaging 14 g/d for three years and a control group who took no supplements. Blood parameters for the creatine group were found to be similar to the control group, with no correlations found between blood parameters and either daily dosage or duration. This led the researchers to suggest that there was no detrimental cumulative effect on either kidney or liver function. Finally, one of the most comprehensive studies to date published in Molecular and Cellular Biochemistry examined long-term CrS in 98 Division IA college American football players over a 21-month period, with athletes ingesting 15.75 g/d for five days and an average of five g/d thereafter. At the end of the study, subjects were categorized into groups: no CrS (n=44); CrS 0-6 months (n=12); CrS 7-12 months (n=25); CrS 12-21 months (n=17). No differences were reported among groups for the 54-item panel of urine and blood markers. The authors suggest that long-term CrS does not appear to cause clinically significant side effects.
Do You Need to Cycle Creatine?
This is an individual preference as some athletes like to cycle creatine while others don’t. To date, there is no research that concludes whether it is beneficial to cycle creatine. If you decide to cycle creatine, I recommend a 12:4 cycle (taking it for 12 weeks and then off for four weeks). When you commence the next cycle, follow the same loading procedure again.
Take Home Message
An extensive review on the health risks associated with excess CrS published in Sports Medicine in 2000 suggests that CrS induces no real modification in hepatic function in healthy individuals and athletes. The studies reviewed above supports previous opinion that CrS does not result in clinically significant increases in liver damage or impaired liver function. However, this does not mean that CrS should be used indiscriminately with no regard for dosage.
Train hard, and remember: quality nutrition equals quality performance.
- Poortmans JR, Francaux M. 2000, Adverse effects of creatine supplementation. Sports Medicine. 30(3): 155-170.
- Robinson TM, Sewell DA, Casey A, Steenge G, Greenhaff PL. 2000, Dietary creatine supplementation does not affect some haematological indices, or indices of muscle damage and hepatic and renal function. British Journal of Sports Medicine. 34: 284-288
- Waldron JE, Pendlay GW, Kilgore TG, Haff GG, Reeves JS, Kilgore JL. 2002, Effects of Concurrent Creatine Monohydrate Supplementation and Resistance Training on Markers of Hepatic Function in Trained Weightlifters. Journal of Exercise Physiology Online 5(1): 57-64. viewed 27 May 2006. http://faculaty.css.edu/tboone2/asep/Kilgore.pdf
- Mayhew DL, Meyhew JL, Ware JS. 2002, Effects of long-term creatine supplementation on liver and kidney functions in American college football players. International Journal of Sport Nutrition and Exercise Metabolism. 12(4):453-460
- Kreider RB, Melton C, Rasmussen CJ, Greenwood M, Lancaster S, Cantler EC, Milnor P, Almada AL. 2003, Long-term creatine supplementation does not significantly affect clinical markers of health in athletes. Molecular and Cellular Biochemistry 244(1-2), 95-104.
- Kreider RB. 1998, Creatine, the Next Ergogenic Supplement? In: Sportscience Training & Technology. Internet Society for Sport Science. viewed 27 May 2006. http://sportsci.org/traintech/creatine/rbk.html