Efficacy and safety of guanidinoacetic acid supplementation in healthy men and women

Abstract

Guanidinoacetic acid (GAA) is a natural precursor of creatine and underinvestigation as a novel dietary supplement. However, its use in human nutrition ishampered by limited knowledge on its physiological effectiveness and safety aftersupplementation. The main aims of the present study were: (a) to identify if oral GAAaffects human performance and body composition; (b) to determine the most effectivedose regimen of GAA; and (c) to analyze the incidence and severity of adverse effects ofGAA supplementation. Fifty two (n = 52) male and female college athletes who wereexperienced in exercise training (> 2 years), and who were between 20 and 25 years ofage were included in the study. Participants were randomized in a double-blind design toreceive three different dosages of GAA (1.2 g/day, 2.4 g/day, and 4.8 g/day) or placebo(inulin) by oral administration for 6 weeks. Two-way mixed model ANOVA revealedsignificant increase in lean body mass (P = 0.006), handgrip strength (P = 0.03), andbench press performance (P = 0.014) in participants supplemented with GAA.Supplementation with GAA for 6 weeks had no major effect on indices of anaerobicpower and capacity. Low-dose GAA (1.2 g/day) can be considered as the minimumeffective dose for improving performance characteristics, while the effects are mostconsistently seen in participants receiving 2.4 g/day of GAA. Except for the dose of 4.8g/day of GAA, reported side effects of GAA administration are rather mild (e.g., weightgain, gastrointestinal distress). The findings of this study demonstrate that oral GAA is aneffective performance-enhancing agent with dose-dependent effects and mild side effectsexperienced when ingested over 6 weeks