Groeger, David, O'Mahony, Liam, Murphy, Eileen F et al. · Gut microbes · 2013 · DOI
This study tested whether a beneficial gut bacterium called Bifidobacterium infantis 35624 could reduce inflammation in people with ME/CFS, along with people who have other inflammatory conditions like ulcerative colitis and psoriasis. Participants took either the bacterium or placebo for 6-8 weeks, and researchers measured inflammatory markers in their blood. The bacterium reduced multiple inflammatory markers across all three conditions, suggesting that gut bacteria can influence immune system activity throughout the whole body, not just in the gut.
This study provides evidence that specific probiotics may help reduce systemic inflammation in ME/CFS—a condition where dysregulated immune and inflammatory responses are thought to play a central role. The finding that a single bacterial strain can reduce inflammatory cytokines in ME/CFS alongside other conditions suggests a plausible mechanistic pathway for microbiota-based interventions. This work supports the rationale for investigating targeted probiotic therapies as potential adjunctive treatments for ME/CFS.
This study does not prove that B. infantis 35624 will be clinically effective or improve ME/CFS symptoms—only that it can reduce certain inflammatory markers. The study does not establish causation between inflammation reduction and symptom improvement, nor does it identify which ME/CFS patients might benefit or determine the optimal dosing or duration of treatment. The mechanisms by which this bacterium influences systemic immunity remain unclear from this data alone.
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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