Kreatin räknas väl även bland vetenskapen som ett säkert tillskott.
Mol Cell Biochem. 2003 Feb;244(1-2):95-104. Related Articles, Links
Long-term creatine supplementation does not significantly affect clinical markers of health in athletes.
Kreider RB, Melton C, Rasmussen CJ, Greenwood M, Lancaster S, Cantler EC, Milnor P, Almada AL.
Exercise and Sport Nutrition Laboratory, Department of Human Movement Sciences and Education, The University of Memphis, Memphis, TN, USA.
Richard_Kreider@baylor.edu
Creatine has been reported to be an effective ergogenic aid for athletes. However, concerns have been raised regarding the long-term safety of creatine supplementation. This study examined the effects of long-term creatine supplementation on a 69-item panel of serum, whole blood, and urinary markers of clinical health status in athletes. Over a 21-month period, 98 Division IA college football players were administered in an open label manner creatine or non-creatine containing supplements following training sessions. Subjects who ingested creatine were administered 15.75 g/day of creatine monohydrate for 5 days and an average of 5 g/day thereafter in 5-10 g/day doses. Fasting blood and 24-h urine samples were collected at 0, 1, 1.5, 4, 6, 10, 12, 17, and 21 months of training. A comprehensive quantitative clinical chemistry panel was determined on serum and whole blood samples (metabolic markers, muscle and liver enzymes, electrolytes, lipid profiles, hematological markers, and lymphocytes). In addition, urine samples were quantitatively and qualitative analyzed to assess clinical status and renal function. At the end of the study, subjects were categorized into groups that did not take creatine (n = 44) and subjects who took creatine for 0-6 months (mean 4.4 +/- 1.8 months, n = 12), 7-12 months (mean 9.3 +/- 2.0 months, n = 25), and 12-21 months (mean 19.3 +/- 2.4 months, n = 17). Baseline and the subjects' final blood and urine samples were analyzed by MANOVA and 2 x 2 repeated measures ANOVA univariate tests. MANOVA revealed no significant differences (p = 0.51) among groups in the 54-item panel of quantitative blood and urine markers assessed. Univariate analysis revealed no clinically significant interactions among groups in markers of clinical status. In addition, no apparent differences were observed among groups in the 15-item panel of qualitative urine markers. Results indicate that long-term creatine supplementation (up to 21-months) does not appear to adversely effect markers of health status in athletes undergoing intense training in comparison to athletes who do not take creatine.
Arch Latinoam Nutr. 2002 Jun;52(2):117-27. Related Articles, Links
[Creatine: the nutritional supplement for exercise - current concepts]
[Article in Portuguese]
Mendes RR, Tirapegui J.
Departamento de Alimentos e Nutricao Experimental, Laboratorio de Nutricao, Faculdade de Ciencias Farmaceuticas Universidade de Sao Paulo, SP, Brasil.
Creatine, a natural nutrient found in animal foods, is alleged to be an effective nutritional ergogenic aid to enhance sport or exercise performance. It may be formed in kidney and liver from arginina and glicina. Creatine may be delivered to the muscle, where it may combine readily with phosphate to form creatine phosphate, a high-energy phosphagen in the ATP-CP system, and is stored. The ATP-CP energy system is important for rapid energy production, such as in speed and power events. Approximately 120 g of creatine is found in a 70 kg male, 95% in the skeletal muscle. Total creatine exists in muscle as both free creatine (40%) and phosphocreatine (60%). It is only recently that a concerted effort has been undertaken to investigate its potential ergogenic effect relative to sport or exercise performance. It does appear that oral creatine monohydrate may increase muscle total creatine, including both free and phosphocreatine. Many, but not all studies suggest that creatine supplementation may enhance performance in high intensity, short-term exercise task that are dependent primarily on the ATP-CP energy system, particularly on laboratory test involving repeated exercise bouts with limited recovery time between repetitions. Short-term creatine supplementation appears to increase body mass, although the initial increase is most likely water associated with the osmotic effect of increased intramuscular total creatine. Chronic creatine supplementation in conjunction with physical training involving resistance exercise may increase muscle mass. However, confirmatory research data are needed. Creatine supplementation up to 8 weeks, with high doses, has not been associated with major health risks; with low doses, it was demonstrated that in 5 years period supplementation, there are no adverse effects. The decision to use creatine as a mean to enhance sport performance is left to the description to the individual athlete.