The effect of creatine intake on renal function.
ABSTRACT 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.
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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; DOI:10.1016/j.nutres.2014.04.003 · 2.59 Impact Factor
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ABSTRACT: The food supplement creatine (Cr) is widely used by athletes as a natural ergogenic compound. It has also been increasingly tested in neurodegenerative diseases as a potential neuroprotective agent. Weight gain is the most common side effect of Cr, but sporadic reports about the impairment of renal function cause the most concerns with regard to its long-term use. Data from randomized controlled trials on renal function in Cr-supplemented patients are scarce and apply mainly to healthy young athletes. We systematically evaluated potential side effects of Cr with a special focus on renal function in aged patients with Parkinson disease as well as its current use in clinical medical research. Sixty patients with Parkinson disease received either oral Cr (n = 40) or placebo (n = 20) with a dose of 4 g/d for a period of 2 years. Possible side effects as indicated by a broad range of laboratory blood and urine tests were evaluated during 6 follow-up study visits. Overall, Cr was well tolerated. Main side effects were gastrointestinal complaints. Although serum creatinine levels increased in Cr patients because of the degradation of Cr, all other markers of tubular or glomerular renal function, especially cystatin C, remained normal, indicating unaltered kidney function. The data in this trial provide a thorough analysis and give a detailed overview about the safety profile of Cr in older age patients.Nutrition research 04/2008; 28(3):172-8. DOI:10.1016/j.nutres.2008.01.001 · 2.59 Impact Factor
Article: Creatine and other supplements.[Show abstract] [Hide abstract]
ABSTRACT: Ergogenic dietary supplement use is highly prevalent among adolescent and collegiate athletes, and use is increasing. To make appropriate recommendations for or against use by individual athletes, physicians who work with adolescent athletes should be knowledgeable about the most commonly used supplements and be able to access high-quality information about others. This article first discusses the legal and regulatory environment of dietary supplements. Several of the most commonly used supplements are then discussed in detail, including creatine, beta-hydroxy-beta-methylbutyrate, protein, amino acids, stimulants, alkalotic agents, glycerol, vitamins, and minerals. Finally, the "Gateway Theory" as it may relate to adolescent supplement and other drug use is discussed.Pediatric Clinics of North America 09/2007; 54(4):735-60, xi. DOI:10.1016/j.pcl.2007.04.009 · 2.20 Impact Factor