The process of creatine synthesis occurs in two steps, catalyzed by L-arginine:glycine
amidinotransferase (AGAT) and guanidinoacetate N-methyltransferase (GAMT), which take place
mainly in kidney and liver, respectively. This molecule plays an important energy/pH buffer function
in tissues, and to guarantee the maintenance of its total body pool, the lost creatine must be replaced
from diet or de novo synthesis. Creatine administration is known to decrease the consumption of Sadenosyl
methionine and also reduce the homocysteine production in liver, diminishing fat
accumulation and resulting in beneficial effects in fatty liver and non-alcoholic liver disease. Different studies have shown
that creatine supplementation could supply brain energy, presenting neuroprotective effects against the encephalopathy
induced by hyperammonemia in acute liver failure. Creatine is also taken by many athletes for its ergogenic properties.
However, little is known about the adverse effects of creatine supplementation, which are barely described in the
literature, with reports of mainly hypothetical effects arising from a small number of scientific publications. Antioxidant
effects have been found in several studies, although one of the theories regarding the potential for toxicity from creatine
supplementation is that it can increase oxidative stress and potentially form carcinogenic compounds.