E1 ReplicatedPreliminaryPEM not requiredRCTPeer-reviewedReviewed
Supplementation with Guanidinoacetic Acid in Women with Chronic Fatigue Syndrome.
Ostojic, Sergej M, Stojanovic, Marko, Drid, Patrik et al. · Nutrients · 2016 · DOI
Quick Summary
Researchers tested whether a supplement called guanidinoacetic acid (GAA) could help women with ME/CFS. Twenty-one women took either GAA or a placebo for three months. While GAA increased muscle creatine levels and improved some measures of strength and aerobic power, it did not reduce fatigue or muscle pain—the main symptoms patients care about most.
Why It Matters
This study directly addresses the need for evidence-based interventions in ME/CFS, a condition with no approved treatments. It illustrates an important disconnect: a supplement can produce measurable metabolic changes (increased creatine) without improving the core symptoms that disable ME/CFS patients (fatigue and pain).
Observed Findings
- Muscular creatine levels increased 36.3% in the GAA group versus 2.4% in placebo (p<0.01).
- Muscular strength and aerobic power showed significantly greater improvements in the GAA group compared to placebo (p<0.05).
- Multidimensional Fatigue Inventory general fatigue score did not differ significantly between GAA and placebo groups.
- Musculoskeletal soreness at rest and during activity showed no significant difference between groups.
- No serious adverse events were reported during the study.
Inferred Conclusions
- GAA supplementation can enhance creatine metabolism and work capacity in women with CFS.
- Biochemical improvements in creatine availability do not necessarily translate to clinical symptom relief in ME/CFS.
- GAA alone is insufficient as a treatment for core ME/CFS symptoms (fatigue and pain).
Remaining Questions
- Why does increased muscular creatine not translate to reduced fatigue in ME/CFS patients?
- Would longer supplementation periods or higher doses of GAA produce clinical symptom improvement?
- Are there subgroups of ME/CFS patients who might benefit more from creatine-enhancing interventions?
What This Study Does Not Prove
This study does not prove that GAA is ineffective for ME/CFS—it only shows no effect on the primary clinical outcomes measured in this small sample. It does not establish that creatine metabolism abnormalities are not important in ME/CFS, only that increasing creatine alone does not resolve fatigue or pain. The small sample size and short intervention period limit generalizability.
Tags
Symptom:PainFatigue
Biomarker:MetabolomicsBlood Biomarker
Method Flag:PEM Not DefinedSmall SampleSex-StratifiedWeak Case Definition
Metadata
- DOI
- 10.3390/nu8020072
- PMID
- 26840330
- Review status
- Editor reviewed
- Evidence level
- Replicated human evidence from multiple independent studies
- Last updated
- 12 April 2026
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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