Creatine long-term

There are no known long-term psychological effects from creatine supplementation. However, at least one study has linked the use of performance-enhancing supplements to an increased incidence of health risk behaviors. The 2001 study, which surveyed approximately 500 men and women between the ages of 17 and 35, found that study participants who took ergogenic nutritional supplements such as creatine were more likely to get drunk, drink and drive, and become involved in physical confrontations. However, since the research was limited by the fact that it involved a very specific population (subjects were new recruits entering military service), further study is needed to determine if ergogenic aids such as creatine are directly linked to an increase in these behaviors. 

Pregnant women, women who breastfeed, and children and adolescents under 18 years of age should avoid creatine use, as its long-term effect on these populations has not been adequately studied. Individuals with chronic medical conditions should consult with their healthcare professional before taking creatine or any other dietary supplement. 

The data on the long-term health effects of creatine supplementation is extremely limited. However, at least one animal study has found that creatine caused a decline in kidney function in rats with existing renal (kidney) disease. In addition, published case reports have indicated that creatine can cause further renal impairment in people with pre-existing kidney disease. However, several studies of healthy athletes have shown that both short-term and extended creatine supplementation had no effect on kidney function. 

Creatine is not recommended for use by individuals with kidney problems, or by anyone at risk for kidney disease (such as those with a family history of kidney problems or diabetes). Again, further controlled clinical studies are needed to determine the long-term impact and safety of creatine supplement use on human renal function. 

Cardiac enzyme elevation (creatine kinase-MB, cardiac troponin) may occur on average in 20% to 30% of patients after PCI and is associated with adverse clinical outcomes in the short- and long-term (64), Magnetic resonance imaging... 

There is little information on the short- or long-term side effects on the safety of creatine supplementation. However, there have been reports of some athletes suffering side effects with the alleged overdosing of creatine (e.g, the natural production of creatine being curtailed in the athlete s body). The European Commission s Scientific Committee on Food (September 7, 2000) has concluded that high doses of creatine supplementation should be avoided (i.e., > 3 grams per day). 

In addition to the established vitamins, a number of organic compounds have clear metabolic functions they can be synthesized in the body, but it is possible that under some circumstances (as in premature infants and patients maintained on long-term total parenteral nutrition) endogenous synthesis may not be adequate to meet requirements. These compounds include biopterin (Section 10.4), carnitine (Section 14.1), choline (Section 14.2), creatine (Section 14.3), inositol (Section 14.4), molybdopterin (Section 10.5), taurine (Section 14.5), and ubiquinone (Section 14.6). 

In a report dating from 1987, low selenium concentrations were found in four children receiving long-term parenteral nutrition. There was erythrocyte macrocytosis (n — 3), loss of pigmentation of hair and skin (n = 2), raised transaminase and creatine kinase activities (n — 2), and profound muscle weakness n = 1). Intravenous supplementation with selenium for 3-12 months resulted in progressive improvement in all these (70). 

Double-blind placebo-controlled studies of oral supplementation of creatine in human subjects have shown increased performance during short duration, strenuous, high-intensity exercise. Such activities require that ATP be replenished rapidly from phosphocreatine stores during anaerobic metabolism. These studies usually consisted of ingestion of 20 g of creatine per day for 5 days followed by a maintenance dose of 5-10 g/day. Studies on creatine as an ergogenic aid have not been uniformly positive some have shown no beneficial effect and still others have been equivocal and indicated that creatine supplementation did not enhance athletic activities. The safety issues of long-term creatine supplementation on kidney, liver, nerve, muscle, and other tissues are not known. 

Poortsmans JR, Erancaux M. Long-term oral creatine supplementation does not impair renal function in healthy athletes. Med Sci Sports Exerc 1999 31 1108-1110. 

EXAMPLE 13.30 Creatine phosphate concentration in the cytoplasm of skeletal muscle is 15 mM. Since the rate of ATP consumption during intense exercise is 3 mmol L s , there is potentially a 5 s supply of creatine phosphate. Many sprinters and power lifters attempt to increase the amount of creatine phosphate in their muscles by ingesting creatine as a dietary supplement. There is strong evidence to suggest that this strategy is effective, but the long-term effects on general health, particularly kidney function, are yet to be determined. 

A three-enzyme electrode system, such as needed for creatinine measurement, poses a more difficult enzyme-immobilisation problem, in that different enzymes have different immobilisation requirements and their microenvironmental interrelationships need to be optimised. For one creatine sensor, the requisite creatine amidinohydrolase and sarcosine oxidase were immobihsed in polyurethane pre-polymer and PEG-hnked creatinine amidohydrolase was attached via diisocyanate pre-polymer to create a polyurethane adduct [14]. The likelihood of enzyme inactivation with chemical immobih-sation is high, but provided an enzyme preparation survives this, long-term stability is feasible. In the case of these three particular enzymes, a loss of activity resulted from silver ions diffusing from the reference electrode the material solution was to protect the enzyme layer with a diffusion-resisting cellulose acetate membrane. 

Myopathy In individuals receiving long-term LNZ therapy, rhabdomyolysis is possible and should be considered in the differential diagnosis of elevated AST or creatine kinase (CK) level. 

Kreider, R., M. Greenwood, C. Melton, C. Rasmussen, E. Cantler, R Milner, and A. Almada, Long-term creatine supplementation during training/competition does not increase perceptions of fatigue or adversely affect health status. Med Sci Sport Exerc,... 

Preen, D., B. Dawson, C. Goodman, S. Lawrence, J. Beilby, and S. Ching, Effect of creatine loading on long-term sprint exercise performance and metabolism. Med Sci... 

Kreider, R.B., C. Melton, C.J. Rasmussen, M. Greenwood, S. Lancaster, E.C. Cantler, P. Milnor, and A.L. Almada, Long-term creatine supplementation does not significantly affect clinical markers of health in athletes. Mol Cell Biochem, 244 95-104, 2003. 

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