Small Intestinal Bacterial Overgrowth Is Associated with Non-Alcoholic Fatty Liver Disease

J Gastrointestin Liver Dis. 2016 Jun;25(2):159-65. doi: 10.15403/jgld.2014.1121.252.iwg.


Background: Changes in gut bacteria play a role in type 2 diabetes mellitus (DM) and hepatic steatosis. There is a lack of studies evaluating the frequency and risk factors for non-alcoholic fatty liver disease (NAFLD) in patients tested for small intestinal bacterial overgrowth (SIBO).

Aim: To evaluate the frequency of NAFLD and associated risk factors in patients tested for SIBO.

Methods: In this case-control study, 372 eligible patients submitted to glucose hydrogen/methane breath test for SIBO who also had an abdominal imaging study were included. Patients were divided into SIBO-positive and SIBO-negative groups. Clinical, demographic and laboratory variables were evaluated in addition to the presence of NAFLD on abdominal imaging.

Results: Of the 372 eligible patients, 141 (37.9%) were tested positive for SIBO (study group) and 231 (62.1%) were negative for it (control group). NAFLD occurred in 45.4% (64/141) of the study group compared to 17.3% (40/231) of the control group (p<0.001). Patients in the study group were found to have higher rates of elevated aspartate aminotransferase (AST) (20.6% vs. 11.3%; p=0.034) and alanine aminotransferase (ALT) levels (56.0% vs. 40.7%; p= 0.039), type 2 diabetes (23.4% vs. 13.9%; p=0.041), hypertension (54.6% vs. 40.3%; p=0.046) and metabolic syndrome (78.0% vs. 60.2%; p=0.020). In the multivariate analysis, SIBO (odds ratio [OR]: 1.95; 95% confidence interval [CI]: 1.14-3.31; p=0.014), type 2 DM (OR: 3.04; 95%CI: 1.57-5.90; p=0.001) and obesity (OR: 3.58; 95%CI: 1.70-7.54; p=0.001) remained associated with NAFLD.

Conclusion: Patients with SIBO have an increased risk for hepatic steatosis and may benefit from aggressive control of the risk factors for NAFLD including metabolic syndrome.

MeSH terms

  • Bacteria / growth & development*
  • Breath Tests
  • Chi-Square Distribution
  • Electronic Health Records
  • Female
  • Gastrointestinal Microbiome*
  • Humans
  • Intestine, Small / microbiology*
  • Logistic Models
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Multivariate Analysis
  • Non-alcoholic Fatty Liver Disease / diagnostic imaging
  • Non-alcoholic Fatty Liver Disease / microbiology*
  • Odds Ratio
  • Predictive Value of Tests
  • Retrospective Studies
  • Risk Factors
  • Tomography, X-Ray Computed
  • Ultrasonography