Creatine: Endogenous Metabolite, Dietary, and Therapeutic Supplement

Abstract

Creatine and phosphocreatine serve not only as an intracellular buffer for adenosine triphosphate, but also as an energy shuttle for the movement of high-energy phosphates from mitochondrial sites of production to cytoplasmic sites of utilization. The spontaneous loss of creatine and of phosphocreatine to creatinine requires that creatine be continuously replaced; this occurs by a combination of diet and endogenous synthesis. Vegetarians obtain almost no dietary creatine. Creatine synthesis makes major demands on the metabolism of glycine, arginine, and methionine. Large doses of creatine monohydrate are widely taken, particularly by athletes, as an ergogenic supplement; creatine supplements are also taken by patients suffering from gyrate atrophy, muscular dystrophy, and neurodegenerative diseases. Children with inborn errors of creatine synthesis or transport present with severe neurological symptoms and a profound depletion of brain creatine. It is evident that creatine plays a critical, though underappreciated, role in brain function.

Comparison of the Amino Acid and Peptide Composition and Postprandial Response of Beef, Chicken, and Whey Protein Nutritional Preparations

“…Glycine may contribute to MPS and gains in body composition indirectly by supporting the synthesis and metabolism of creatine, which has been shown to improve lean body mass [37]. Creatine, along with phosphocreatine, plays a key role in cellular production and utilization of ATP [38], particularly in skeletal muscle. Because creatine is spontaneously converted to creatinine and excreted in urine, it must be continuously replaced by a combination of diet and endogenous synthesis.…”

“…Because creatine is spontaneously converted to creatinine and excreted in urine, it must be continuously replaced by a combination of diet and endogenous synthesis. Creatine synthesis requires the whole glycine molecule, the amidino group of arginine, and methylation typically provided by methionine [38]. Due to consumption of the entire glycine molecule in creatine synthesis it has been estimated that 16% of daily dietary glycine intake is required for creatine synthesis alone [38].…”

Metabonomic and Microbiological Analysis of the Dynamic Effect of Vancomycin-Induced Gut Microbiota Modification in the Mouse

“…In the human gut, the anaerobic genus Clostridium were found to metabolize leucine to isocaproate and R-ketoisocaproate; 63 and creatine has also been shown to be co-metabolized in mammals and their gut microbiota. 64,65 Perturbed gut microbial changes observed in SCFAs, oligosaccharides and amino acids indicated vancomycin-induced changes in metabolism of these compounds, which may also explain the change in the relative amounts of R-ketoisocaproate and creatine in the urine.…”

Maternal creatine supplementation from mid-pregnancy protects the newborn spiny mouse diaphragm from intrapartum hypoxia-induced damage

“…These results provide evidence that creatine supplementation during pregnancy may protect respiratory function in the neonate during the critical period immediately after birth. Although the many benefits of creatine therapy have been reviewed recently (40), its use in pregnancy has not been fully considered. This study also confirmed that dietary intervention during pregnancy provides a simple and effective means to prevent many of the deleterious effects arising from intrapartum hypoxia.…”