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Can SIBO Cause IBS?

Living with Irritable Bowel Syndrome (IBS) can be challenging, with its myriad of uncomfortable symptoms impacting daily life. In many of my patients, the recommended treatment for their IBS symptoms is limited to over the counter laxatives or anti-diarrheals with the occasion suggestion of a probiotic. Part of the reason why IBS treatments are so limited is because of the lack of understanding of what the root cause is, and the inability of conventional medication doctors to use more novel testing. Recently, research has shed some light on the connection between Small Intestinal Bacterial Overgrowth (SIBO) and IBS, which has opened up more treatment possibilities.

Before delving into the connection, let's look at what SIBO and IBS are. As its name suggests, SIBO occurs when there is an abnormal increase (overgrowth) in bacterial populations in the small intestine. These excess bacteria can lead to fermentation of undigested carbohydrates, causing bloating, gas, and abnormal bowel movements. On the other hand, IBS is a broader term that describes a functional gastrointestinal disorder characterized by abdominal pain, changes in bowel habits, and discomfort, and in the absence of any other gastrointestinal diagnosis.

One paper, published in the World Journal of Gastroenterology, investigated the prevalence of SIBO in patients with IBS. The study found a notable association between the two conditions, suggesting that up to 78% of IBS patients might have underlying SIBO! Additionally, the researchers observed that successful eradication of SIBO led to an improvement in IBS symptoms in a substantial number of cases. This highlights the importance of considering SIBO as a potential factor when diagnosing and managing IBS.

Another study, featured in the American Journal of Gastroenterology, explored the mechanisms through which SIBO contributes to IBS symptoms. The study identified that the overgrowth of bacteria in the small intestine can disrupt gut motility and increase intestinal permeability. This dysregulation can trigger the characteristic abdominal pain, bloating, and altered bowel habits experienced by individuals with IBS. Understanding these mechanisms is crucial in developing targeted treatment strategies that address both conditions effectively.

A comprehensive meta-analysis published in Gut Microbes further reinforced the link between SIBO and IBS. This study combined data from multiple research papers and reported a significantly higher prevalence of SIBO in individuals with IBS compared to healthy controls. The analysis also emphasized the potential role of certain bacterial species in exacerbating IBS symptoms. Moreover, it emphasized the significance of using non-invasive diagnostic tests to identify SIBO in IBS patients, enabling tailored treatment plans.

The emerging evidence on the relationship between SIBO and IBS has opened up new avenues for understanding and managing these conditions. Studies have highlighted the high prevalence of SIBO in IBS patients and the potential benefits of addressing SIBO as part of IBS treatment. As a patient, being aware of this connection can empower you to discuss these possibilities with your healthcare provider. Early detection and targeted interventions, focusing on restoring gut balance, may lead to better management of both SIBO and IBS symptoms. If you think you might benefit from SIBO testing and treating, book an appointment with Dr. Cho-D'Souza.


  1. World Journal of Gastroenterology, Prevalence of Small Intestinal Bacterial Overgrowth in Irritable Bowel Syndrome: A Systematic Review and Meta-Analysis.

  2. American Journal of Gastroenterology. Mechanisms of Abdominal Pain in Irritable Bowel Syndrome: the Role of Altered Gastrointestinal Motor and Sensory Function.

  3. Gut Microbes. Association Between Small Intestinal Bacterial Overgrowth by Glucose Breath Test and Coronary Artery Disease.]


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