Pathophysiology: Gut Microbiome

Full Citation:: Lupo GFD, Rocchetti G, Lucini L, et al. Potential role of microbiome in Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME). Scientific Reports. 2021;11(1):7043. DOI:: 10.1038/s41598-021-86425-6

Full Citation:: Giloteaux L, Goodrich JK, Walters WA, Levine SM, Ley RE, Hanson MR. Reduced diversity and altered composition of the gut microbiome in individuals with myalgic encephalomyelitis/chronic fatigue syndrome. Microbiome. 2016;4(1):30. DOI:: 10.1186/s40168-016-0171-4 Key Findings:: Reduced Faecalibacterium prausnitzii and Eubacterium rectale (butyrate producers).

Full Citation:: K"onig RS, Albrich WC, Kahlert CR, et al. The Gut Microbiome in Myalgic Encephalomyelitis (ME)/Chronic Fatigue Syndrome (CFS). Frontiers in Immunology. 2022;12:628741. DOI:: 10.3389/fimmu.2021.628741 PMCID:: PMC8761622

Full Citation:: Varesi A, Campagnoli LIM, Frasca A, et al. The gastrointestinal microbiota in the development of ME/CFS: a critical view and potential perspectives. Frontiers in Immunology. 2024;15:1352744. DOI:: 10.3389/fimmu.2024.1352744

Full Citation:: Ciregia F, Rahmania F, Semenova-Ziga V, Ortega-Molina M, Rodrigues M, Gonzalez-Lopez E. Increased gut permeability and bacterial translocation are associated with fibromyalgia and myalgic encephalomyelitis/chronic fatigue syndrome: implications for disease-related biomarker discovery. Frontiers in Immunology. 2023;14:1253121. DOI:: 10.3389/fimmu.2023.1253121 Key Findings:: Elevated markers of gut permeability and bacterial translocation.

Full Citation:: Karhu E, Neshatian L, Fass O, Sonu I, Nguyen LA. S1821 Prevalence and Predictive Factors of Small Intestinal Bacterial Overgrowth in Patients With Chronic Fatigue Syndrome. The American Journal of Gastroenterology. 2023;118(10S):S1351–S1352. DOI:: 10.14309/01.ajg.0000956924.26236.c4 Study Design:: Retrospective chart review (n=479 referred; n=367 completed breath test) Key Findings:: Of 479 referred, 367 completed breath testing; 316 yielded conclusive results. 48% SIBO-positive in conclusive results (152/316); 41% overall (152/367); 45% negative; 14% equivocal. Older age and IBS comorbidity predicted positive breath test. Published as ACG 2023 conference abstract. Relevance:: First substantial prevalence estimate for SIBO specifically in a ME/CFS population; supports GI bacterial overgrowth as a common contributor to GI symptom burden. Limitations:: Conference abstract; retrospective design; referral bias (patients referred for breath testing had more GI symptoms); results not peer-reviewed in full-paper format.

Full Citation:: Pimentel M, Constantino T, Kong Y, Bajwa M, Rezaei A, Park S. A 14-day elemental diet is highly effective in normalizing the lactulose breath test. Digestive Diseases and Sciences. 2004;49(1):73–77. DOI:: 10.1023/b:ddas.0000011605.43979.e1 PMID:: 14992438 Study Design:: Prospective intervention study (n=93, IBS with abnormal lactulose breath test) Key Findings:: Exclusive elemental diet (Vivonex Plus) normalized lactulose breath test in 80% of subjects at day 15 and 85% including those extended to day 21. Successful normalisers had 66% bowel symptom improvement vs 12% in those who failed to normalize. Relevance:: Landmark demonstration that elemental diet can eradicate SIBO by starving bacteria of fermentable substrates; basis for current clinical practice recommendations of 14–21 day elemental diet protocols. Limitations:: IBS population only (not ME/CFS-specific); lactulose breath test used (lower specificity than glucose breath test or jejunal culture); no control arm; symptom improvement self-reported.

Full Citation:: Rezaie A, Chang BW, de Freitas Germano J, et al. Effect, Tolerability, and Safety of Exclusive Palatable Elemental Diet in Patients With Intestinal Microbial Overgrowth. Clinical Gastroenterology and Hepatology. 2025;23(12):2306–2317.e7. DOI:: 10.1016/j.cgh.2025.03.002 PMID:: 40189034 Study Design:: Prospective clinical trial (palatable elemental formula; SIBO and IMO patients) Key Findings:: 83% overall eradication rate; 100% in hydrogen-dominant SIBO (n=6), 58% in IMO (n=12); 66% symptom improvement in responders. Palatable formulation improved tolerability vs traditional Vivonex Plus. Relevance:: Updates the 2004 Pimentel study with modern palatable formula; confirms elemental diet efficacy and improves adherence; mBIOTA Elemental formula now available clinically. Limitations:: Small sample size, particularly for IMO subgroup; single-centre; no RCT design.