Guanidinoacetic benefit, role
October 1 2015

Guanidinoacetic acid (GAA) is the natural biosynthetic precursor of creatine, in a metabolic reaction that requires only a methyl group transfer.

Eur J Nutr. 2015 Sep 28. Advanced physiological roles of guanidinoacetic acid. Dietary guanidinoacetic acid (GAA) seems to improve cellular bioenergetics by stimulating creatine biosynthesis. However, GAA could have other biological functions that might affect its possible use as a food ingredient in human nutrition. In this paper, we identified several alternative physiological roles of supplemental GAA, including the stimulation of hormonal release and neuromodulation, an alteration of metabolic utilization of arginine, and an adjustment of oxidant-antioxidant status. A better knowledge of how GAA affects human physiology may facilitate its use as an experimental nutritional intervention for novel purposes and conditions.

Int J Med Sci. 2013. Creatine metabolism and safety profiles after six-week oral guanidinoacetic acid administration in healthy humans. Guanidinoacetic acid (GAA) is a natural precursor of creatine, yet the potential use of GAA as a nutritional additive for restoring creatine availability in humans has been limited by unclear efficacy and safety after exogenous GAA administration. The present study evaluated the effects of orally administered GAA on serum and urinary GAA, creatine and creatinine concentration, and on the occurrence of adverse events in healthy humans. Twenty-four healthy volunteers were randomized in a double-blind design to receive either GAA (2.4 grams daily) or placebo (PLA) by oral administration for 6 weeks. Clinical trial registration: www.clinicaltrials.gov, identification number NCT01133899. Serum creatine and creatinine increased significantly from before to after administration in GAA-supplemented participants (P < 0.05). The proportion of participants who reported minor side effects was 58.3% in the GAA group and 45.5% in the placebo group. A few participants experienced serum creatine levels above 70 Ámol/L. Exogenous GAA is metabolized to creatine, resulting in a significant increase of fasting serum creatine after intervention. GAA had an acceptable side-effects profile with a low incidence of biochemical abnormalities.

Guanidinoacetate methyltransferase deficiency

Brain creatine depletion: guanidinoacetate methyltransferase deficiency (improving with creatine supplementation).
Neurology. 2000. Dipartimento di Scienze Neurologiche e Psichiatriche dell'Eta Evolutiva, Universita La Sapienza, Rome, Italy.
The authors describe an Italian child with guanidinoacetate methyltransferase deficiency, neurologic regression, movement disorders, and epilepsy during the first year of life. Brain MRI showed pallidal and periaqueductal alterations. In vivo 1H-MRS showed brain creatine depletion. The assessment of guanidinoacetic acid concentration in biologic fluids confirmed the diagnosis. Clinical, biochemical, and neuroradiologic improvement followed creatine supplementation.