Association Between Small Intestinal Bacterial Overgrowth by Glucose Breath Test and Coronary Artery Disease

Dig Dis Sci. 2018 Feb;63(2):412-421. doi: 10.1007/s10620-017-4828-z. Epub 2017 Nov 6.


Background: A possible role of gut bacteria and their metabolic by-products in the development of coronary artery disease (CAD) is suspected. There is a lack of studies evaluating the association of small intestinal bacterial overgrowth (SIBO) with the development of CAD.

Aim: To evaluate the frequency and risk factors for angiography-confirmed CAD in patients with or without SIBO.

Methods: A total of 1059 patients tested for SIBO using the glucose hydrogen/methane breath test from 2006 to 2014 were evaluated. In total, 160 had coronary artery angiography and were included in the study. SIBO-positive patients were compared to SIBO-negative patients. Demographic, clinical, and laboratory variables and the presence of CAD on coronary angiography were analyzed.

Results: Patients with SIBO had a higher frequency of CAD (78.9 vs. 38.6%, p < 0.001), diabetes mellitus (40.0 vs. 22.9%, p = 0.016), chronic kidney disease (26.7 vs. 12.9%, p = 0.025), use of angiotensin conversion enzyme inhibitor/blocker (45.5 vs. 32.9%, p = 0.008), and statins (75.6 vs. 61.4%, p = 0.004). Patients with SIBO had an increased number of coronary arteries affected compared to SIBO-negative patients (1-vessel disease 67.2 vs. 32.8%, p < 0.001; 2-vessel disease 85.7 vs. 14.3%, p < 0.001; and 3-vessel disease 82.4 vs. 17.6%, p < 0.001, respectively). In the stepwise multivariate logistic regression analysis, SIBO remained an independent risk factor for CAD (odds ratio 7.18, 95% confidence interval 3.09-16.67; p < 0.001).

Conclusion: SIBO was found to be associated with CAD and with the number of coronary arteries involved in this study from a single tertiary center. Further studies are necessary to confirm the association of SIBO with CAD. In the presence of risk factors, patients with SIBO may benefit from assessment for CAD.

Keywords: Coronary artery disease; Metabolic disease; Small intestinal bacterial overgrowth.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Breath Tests*
  • Coronary Disease / microbiology*
  • Female
  • Gastrointestinal Microbiome
  • Glucose / chemistry*
  • Humans
  • Hydrogen / chemistry
  • Hydrogen / metabolism
  • Intestine, Small / microbiology*
  • Male
  • Methane / chemistry
  • Methane / metabolism
  • Middle Aged
  • Retrospective Studies
  • Risk Factors


  • Hydrogen
  • Glucose
  • Methane