A systematic review of enteric dysbiosis in chronic fatigue syndrome/myalgic encephalomyelitis

Syst Rev. 2018 Dec 20;7(1):241. doi: 10.1186/s13643-018-0909-0.


Background: Chronic fatigue syndrome or myalgic encephalomyelitis (CFS/ME) is an illness characterised by profound and pervasive fatigue in addition to a heterogeneous constellation of symptoms. The aetiology of this condition remains unknown; however, it has been previously suggested that enteric dysbiosis is implicated in the pathogenesis of CFS/ME. This review examines the evidence currently available for the presence of abnormal microbial ecology in CFS/ME in comparison to healthy controls, with one exception being probiotic-supplemented CFS/ME patients, and whether the composition of the microbiome plays a role in symptom causation.

Methods: EMBASE, Medline (via EBSCOhost), Pubmed and Scopus were systematically searched from 1994 to March 2018. All studies that investigated the gut microbiome composition of CFS/ME patients were initially included prior to the application of specific exclusion criteria. The association between these findings and patient-centred outcomes (fatigue, quality of life, gastrointestinal symptoms, psychological wellbeing) are also reported.

Results: Seven studies that met the inclusion criteria were included in the review. The microbiome composition of CFS/ME patients was compared with healthy controls, with the exception of one study that compared to probiotic-supplemented CFS/ME patients. Differences were reported in each study; however, only three were considered statistically significant, and the findings across all studies were inconsistent. The quality of the studies included in this review scored between poor (< 54%), fair (54-72%) and good (94-100%) using the Downs and Black checklist.

Conclusions: There is currently insufficient evidence for enteric dysbiosis playing a significant role in the pathomechanism of CFS/ME. Recommendations for future research in this field include the use of consistent criteria for the diagnosis of CFS/ME, reduction of confounding variables by controlling factors that influence microbiome composition prior to sample collection and including more severe cases of CFS/ME.

Keywords: Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME); Dysbiosis; Microbiome; Systematic review.

Publication types

  • Research Support, Non-U.S. Gov't
  • Systematic Review

MeSH terms

  • Dietary Supplements
  • Dysbiosis*
  • Fatigue Syndrome, Chronic / physiopathology*
  • Gastrointestinal Microbiome*
  • Humans
  • Probiotics
  • Quality of Life / psychology*