Human gut microbiota as a source of guanidinoacetic acid.

Guanidinoacetic acid (GAA) is a natural amino acid derivative that acts as a precursor of creatine while being synthesized and utilized in a two-step reaction that takes place in the human kidney and liver. In this paper, we have proposed that guanidinoacetase, an enzyme present in healthy gut microbiota, might contribute to gross GAA turnover by hydrolyzing GAA to glycine and urea or vice versa. Additional studies are thus needed to assess a net gain of this microbiota-driven GAA pathway that may account for energy metabolism homeostasis in general.