To examine the effect of creatine supplementation on renal function and estimates of creatinine clearance.
A MEDLINE search was conducted (1966-September 2004) using the key terms creatine, creatinine, kidney function tests, drug toxicity, and exercise. Relevant articles were cross-referenced to screen for additional information.
Supplementation with creatine, an unregulated dietary substance, is increasingly common in young athletes. To date, few studies have evaluated the impact of creatine on renal function and estimates of creatinine clearance. Because creatine is converted to creatinine in the body, supplementation with large doses of creatine may falsely elevate creatinine concentrations. Five studies have reported measures of renal function after acute creatine ingestion and 4 after chronic ingestion. All of these studies were completed in young healthy populations. Following acute ingestion (4-5 days) of large amounts of creatine, creatinine concentrations increased slightly, but not to a clinically significant concentration. Creatinine is also only minimally affected by longer creatine supplementation (up to 5.6 y).
Creatine supplementation minimally impacts creatinine concentrations and renal function in young healthy adults. Although creatinine concentrations may increase after long periods of creatine supplementation, the increase is extremely limited and unlikely to affect estimates of creatinine clearance and subsequent dosage adjustments. Further studies are required in the elderly and patients with renal insufficiency.
"In fact, mainstream media reports have linked creatine and caffeine supplementation with potential renal and hepatic problems as well as dehydration. However, scientific evidence does not support these conclusions    . "
[Show abstract][Hide abstract] ABSTRACT: The purpose of this study was to determine the safety and efficacy of consuming a pre-workout supplement containing caffeine, creatine, beta-alanine, amino acids, and B-vitamins for 28 days. We hypothesized that little to no changes in kidney and liver clinical blood markers, or resting heart rate and blood pressure would be observed. Additionally, we hypothesized that body composition and performance would improve in recreationally active males following 28 days of supplementation. In a double-blind placebo-controlled study, participants were randomly assigned to ingest one scoop of either the supplement (SUP) or placebo (PL) every day for 28 days, either 20 minutes before exercise or ad libitum on non-exercise days. Resting heart rate and blood pressure, body composition, and fasting blood samples were collected before and after supplementation. Aerobic capacity as well as muscular strength and endurance were also measured. Significant (p < 0.05) main effects for time were observed for resting heart rate (PRE:67.59 ± 7.90b/min, POST:66.18 ± 7.63b/min), systolic blood pressure (PRE:122.41 ± 11.25mmHg, POST:118.35 ± 11.58mmHg), blood urea nitrogen (PRE:13.12 ± 2.55mg/dL, POST:15.24 ± 4.47mg/dL), aspartate aminotransferase (PRE:34.29 ± 16.48 IU/L, POST:24.76 ± 4.71 IU/L), and alanine aminotransferase (PRE:32.76 ± 19.72 IU/L, POST:24.88 ± 9.68 IU/L). Significant main effects for time were observed for %BF (PRE:15.55 ± 5.79%, POST:14.21 ± 5.38%; p = 0.004) and FFM (PRE:70.80 kg ±9.21kg, POST:71.98 kg ± 9.27kg; p = 0.006). A significant decrease in VO2max (PRE: 47.28 ml/kg/min ± 2.69, POST: 45.60 ml/kg/min ± 2.81), and a significant increase in VT% (PRE: 64.38% ± 6.63%, POST:70.63% ± 6.39%) and leg press 1RM (PRE: 218.75kg ± 38.43kg, POST: 228.75kg ± 44.79kg) were observed in the SUP only. No adverse effects were noted for renal and hepatic clinical blood markers, resting heart rate or blood pressure. Supplements containing similar ingredients and doses should be safe for ingestion periods lasting up to 28 days in healthy, recreationally-trained, college-aged men.
Nutrition Research 05/2014; 34(5). DOI:10.1016/j.nutres.2014.04.003 · 2.47 Impact Factor
"On the other hand, serum creatinine is positively correlated with lean body mass thus the serum creatinine level may also reflect the bodily constitution 28, 29. In the context of creatine supplementation several authors observed an increase of serum creatinine 30-32, whereas others did not find the same effect 33-35. Considering the correlation between the serum creatinine level and the increased creatine pool after creatine supplementation 36, a rise in serum and urine creatinine levels after intake of GAA as a precursor of creatine seems plausible. "
[Show abstract][Hide abstract] ABSTRACT: Objectives:
Guanidinoacetic acid (GAA) is a natural precursor of creatine, yet the potential use of GAA as a nutritional additive for restoring creatine availability in humans has been limited by unclear efficacy and safety after exogenous GAA administration. The present study evaluated the effects of orally administered GAA on serum and urinary GAA, creatine and creatinine concentration, and on the occurrence of adverse events in healthy humans.
Methods and results:
Twenty-four healthy volunteers were randomized in a double-blind design to receive either GAA (2.4 grams daily) or placebo (PLA) by oral administration for 6 weeks.
Clinical trial registration:
www.clinicaltrials.gov, identification number NCT01133899. Serum creatine and creatinine increased significantly from before to after administration in GAA-supplemented participants (P < 0.05). The proportion of participants who reported minor side effects was 58.3% in the GAA group and 45.5% in the placebo group (P = 0.68). A few participants experienced serum creatine levels above 70 µmol/L.
Exogenous GAA is metabolized to creatine, resulting in a significant increase of fasting serum creatine after intervention. GAA had an acceptable side-effects profile with a low incidence of biochemical abnormalities.
International journal of medical sciences 01/2013; 10(2):141-147. DOI:10.7150/ijms.5125 · 2.00 Impact Factor
"Urinary methylamine and formaldehyde have been shown to increase due to creatine supplementation of 20 g/d; this however did not bring the production outside of normal healthy range and did not impact on kidney function [56,78]. It has been advised that further research be carried out into the effects of creatine supplementation and health in the elderly and adolescent [73,75]. More recently, a randomized, double blind, 6 month resistance exercise and supplementation intervention  was performed on elderly men and women (age >65 years) in which subjects were assigned to either a supplement or placebo group. "
[Show abstract][Hide abstract] ABSTRACT: Creatine is one of the most popular and widely researched natural supplements. The majority of studies have focused on the effects of creatine monohydrate on performance and health; however, many other forms of creatine exist and are commercially available in the sports nutrition/supplement market. Regardless of the form, supplementation with creatine has regularly shown to increase strength, fat free mass, and muscle morphology with concurrent heavy resistance training more than resistance training alone. Creatine may be of benefit in other modes of exercise such as high-intensity sprints or endurance training. However, it appears that the effects of creatine diminish as the length of time spent exercising increases. Even though not all individuals respond similarly to creatine supplementation, it is generally accepted that its supplementation increases creatine storage and promotes a faster regeneration of adenosine triphosphate between high intensity exercises. These improved outcomes will increase performance and promote greater training adaptations. More recent research suggests that creatine supplementation in amounts of 0.1 g/kg of body weight combined with resistance training improves training adaptations at a cellular and sub-cellular level. Finally, although presently ingesting creatine as an oral supplement is considered safe and ethical, the perception of safety cannot be guaranteed, especially when administered for long period of time to different populations (athletes, sedentary, patient, active, young or elderly).
Journal of the International Society of Sports Nutrition 07/2012; 9(1):33. DOI:10.1186/1550-2783-9-33 · 1.91 Impact Factor
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