GAA, the creatine precursor sold as a brain booster, just got its first serious human test. In a six-week, double-blind trial of 58 healthy adults, it produced some faster reaction times and a scattering of mood and stress signals. Most cognitive tests, however, showed nothing, and many of the headline results were only trends. Safety markers looked fine, but the study was small, exploratory, and had no creatine-only comparison group. Here is what it really shows, who it might suit, and why the verdict is mixed.
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