E0 ConsensusPreliminaryPEM unclearSystematic-ReviewPeer-reviewedReviewed
A systematic review of enteric dysbiosis in chronic fatigue syndrome/myalgic encephalomyelitis.
Du Preez, S, Corbitt, M, Cabanas, H et al. · Systematic reviews · 2018 · DOI
Quick Summary
Researchers reviewed seven studies looking at whether gut bacteria differences might cause ME/CFS symptoms. While all studies found some differences in gut bacteria between ME/CFS patients and healthy people, the findings were inconsistent and often not statistically significant. Currently, there isn't enough reliable evidence to say that abnormal gut bacteria are a major cause of ME/CFS.
Why It Matters
Understanding potential gut microbiome changes in ME/CFS could lead to new diagnostic tools or targeted treatments like probiotics. This systematic review critically evaluates current evidence and identifies the need for higher-quality research using consistent diagnostic criteria and methods, which could ultimately improve how we understand and treat ME/CFS.
Observed Findings
- All seven included studies reported differences in microbiome composition between CFS/ME patients and healthy controls.
- Only three of the seven studies found these differences to be statistically significant.
- Microbiome findings across all studies were inconsistent and varied in methodology and outcomes.
- Study quality varied widely, with ratings ranging from poor (<54%) to good (94-100%).
- The review identified significant confounding variables and lack of standardized diagnostic criteria across studies.
Inferred Conclusions
- Current evidence is insufficient to establish enteric dysbiosis as a significant mechanism in CFS/ME pathogenesis.
- Inconsistent findings highlight the need for more rigorous, methodologically standardized research in this area.
- Future studies should use consistent CFS/ME diagnostic criteria and control for variables known to influence microbiome composition.
- More severe cases of ME/CFS should be included in future microbiome research.
Remaining Questions
- Do specific microbiome alterations correlate with particular ME/CFS symptom profiles or disease severity?
What This Study Does Not Prove
This review does not prove that gut dysbiosis causes ME/CFS symptoms—it only examines whether differences exist. The inconsistency across studies and methodological limitations mean we cannot yet determine whether microbiome changes are a primary cause, secondary effect, or clinically meaningful contributor to ME/CFS pathogenesis.
Tags
Symptom:Fatigue
Method Flag:Weak Case DefinitionSmall SampleMixed Cohort
Metadata
- DOI
- 10.1186/s13643-018-0909-0
- PMID
- 30572962
- Review status
- Editor reviewed
- Evidence level
- Established evidence from major reviews, guidelines, or evidence maps
- 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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