Wallis, Amy, Butt, Henry, Ball, Michelle et al. · Scientific reports · 2016 · DOI
This study looked at gut bacteria in 274 ME/CFS patients and found that certain bacteria may affect symptoms differently in men and women, even when they have similar amounts of these bacteria. Specific bacteria called Firmicutes (including types like Clostridium and Lactobacillus) appeared connected to neurological, immune, and mood symptoms, but the way they affected symptoms depended on the patient's sex. This suggests that sex differences matter when understanding how gut bacteria influence ME/CFS.
This research highlights that sex differences in microbiota-host interactions may be critical for understanding ME/CFS symptom variation and developing targeted treatments. Recognizing that the same bacteria may have different effects in men versus women could lead to more personalized therapeutic approaches, including microbiota-targeted interventions.
This study cannot establish causation—it shows associations only, not whether specific bacteria cause symptoms or symptoms alter bacterial composition. The cross-sectional design means we cannot determine direction of effect, and findings have not yet been replicated in independent ME/CFS populations. Sex-specific effects observed here require mechanistic validation in experimental models.
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 →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Wallis, Amy, Butt, Henry, Ball, Michelle, Lewis, Donald P, & Bruck, Dorothy (2016). Support for the Microgenderome: Associations in a Human Clinical Population.. Scientific reports. https://doi.org/10.1038/srep19171
BibTeX
@article{mecfsatlas-wallis-2016-support-microgenderome,
author = {Wallis, Amy and Butt, Henry and Ball, Michelle and Lewis, Donald P and Bruck, Dorothy},
title = {Support for the Microgenderome: Associations in a Human Clinical Population.},
journal = {Scientific reports},
year = {2016},
doi = {10.1038/srep19171},
note = {PubMed: 26757840},
url = {https://www.mecfsatlas.com/evidence/wallis-2016-support-microgenderome},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/wallis-2016-support-microgenderome
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