Guanidinoacetic Acid (GAA)
The body's direct precursor to creatine. It does raise tissue creatine, but it also raises homocysteine, and it has never been shown to beat simply taking creatine.
Evidence last reviewed: August 2026
What the science says
- Raises muscle and brain creatine Limited evidence
A randomised superiority pilot trial in healthy men found guanidinoacetic acid increased muscle and brain creatine more than creatine monohydrate over several weeks. It was a pilot with very few participants.
- Raises homocysteine Moderate evidence
A randomised, double-blind trial comparing guanidinoacetic acid plus creatine with creatine alone found the GAA arm developed higher plasma homocysteine, an unwanted change, without a clear performance advantage.
- No performance case over creatine Limited evidence
No trial has shown guanidinoacetic acid outperforms creatine monohydrate for exercise performance, and human data cover only weeks to a few months.
Dosage & safety
Scientific references
- Guanidinoacetic acid versus creatine for improved brain and muscle creatine levels: a superiority pilot trial in healthy men
- Guanidinoacetic acid with creatine compared with creatine alone for tissue creatine content, hyperhomocysteinemia, and exercise performance: A randomized, double-blind superiority trial
Where to buy
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Related in Physical performance
- Creatine (monohydrate) Strong evidence
- Whey Protein Strong evidence
- Caffeine Strong evidence
- Beta-Alanine Moderate evidence
- BCAA (Branched-Chain Amino Acids) Limited evidence
- EAA (Essential Amino Acids) Moderate evidence