Long-Term Effects of Creatine
Many ignorant critics of creatine are quick to suggest that there are no long-term studies conducted on creatine supplementation and use this straw man fallacy to state that long-term creatine supplementation is not safe. In fact, there are many long term studies on creatine that have been conducted, all with positive endorsements for its use.
Mayhew et al. (2002) investigated creatine’s long-term effects on liver and kidney function. Twenty-three members of an NCAA Division II American football with at least two years of strength training experience were divided into a creatine monohydrate group in which they voluntarily and spontaneously ingested creatine, and a control in which they took no supplements. Individuals in the creatine monohydrate group averaged regular daily consumption of 5 to 20 g 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. Creatinine clearance was estimated from serum creatinine and was not significantly different between groups. Within the creatine monohydrate group, correlations between all blood parameters and either daily dosage or duration of supplementation were nont significant. Therefore, it appears that oral supplementation with creatine monohydrate has no long-term detrimental effects on kidney or liver functions in highly trained college athletes in the absence of other nutritional supplements.
Derave et al. (2003) studied creatine’s long-term efficiency. Recent findings in healthy humans indicate that the beneficial effect on muscle function and muscle total creatine content may disappear when creatine is continuously ingested for more than two or three months. The mechanism for this habituation to chronic creatine exposure is poorly understood and subsequently unverified.
Kreider et al. (2003) states that long-term creatine supplementation does not significantly affect clinical markers of health in athletes. 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. Results revealed no significant differences 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.
Schroder et al. (2004) used 18 professional basketball players of the first Spanish Basketball League. The participants ingested 5g of creatine monohydrate daily during three competition seasons. Blood was collected in the morning after an overnight fast, five times during each of the three official competition seasons. The results indicate that long-term (3-years) creatine monohydrate supplementation does not produce measurable abnormalities within the 16 clinical tests performed on the athletes.
It has been shown time and time again that there are no long-term adverse effects of creatine supplementation.