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Exploring SIBO and IBS Link – Common Factors You Should Know

Let’s face it. Gut health is often taken for granted, until one day physical symptoms appear and start making our lives uncomfortable, to say the least. There are many factors contributing to gut health, with microbial balance being arguably the most important of them all.

By now, everyone is familiar with friendly neighborhood bacteria that live unappreciated in the darkest parts of our body and help us regulate various processes, including:

  1. Fermentation of undigested dietary residue and endogenous mucus
  2. Protection against pathogens
  3. Metabolism regulation

These microorganisms are so abundant that the human body has 10 times more bacteria than actual cells. However, their work goes unnoticed until, for whatever reason, bacterial balance in our gut gets disrupted and we end up with an excessive level of microorganisms. This is when real problems begin… 


Changes in intestinal microbiota can significantly disrupt the balance in the small intestine. Under normal conditions, our body has protective powers that prevent bacterial overgrowth. This includes intrinsic factors like:

  1. Secretion of bile and gastric juice, which have an antibacterial effect; 
  2. Wavelike muscle contraction that prevents bacteria from attaching to intestines;
  3. Protein production by intestinal mucosal epithelial cell inhibiting pathogenic bacteria; 
  4. Production of antibacterial peptides

Extrinsic factors like diet, drugs, pre and probiotics, can also inhibit bacterial overgrowth. If any of these protective factors fail, our body may develop small intestinal bacterial overgrowth (SIBO).


Small intestinal bacterial overgrowth, commonly known as SIBO, is a condition resulting from bacterial overgrowth in the small intestines. Bacterial overgrowth is a serious health concern and can lead to a host of long-term problems including nutrient deficiency, bloating, irritable bowel syndrome, chronic inflammation, bloating and damage to your stomach lining.

Moreover, growing numbers of bacteria causes bacterial fermentation which leads to production of gases like hydrogen, methane, carbon dioxide, and even hydrogen sulfide. As a result SIBO patients start experiencing symptoms like watery diarrhea, flatulence, abdominal pain and distension, and bloating. Methane production in particular can also lead to constipation.

In addition to that, SIBO patients often show signs of malnutrition and deficiency of vitamins B12, D, A, and E and minerals, like iron and calcium. This means that SIBO has a wide variety of symptoms and different signs can indicate the need for SIBO diagnosis. While some forms of SIBO are relatively easy to treat, timely diagnosis of SIBO is extremely crucial. SIBO symptoms are similar to that of many other diseases, like irritable bowel syndrome (IBS) and many studies have shown that they often come together. So a person with SIBO symptoms might be totally unaware of having other conditions like IBS and thus, neglect it, which can have significant negative effects for patient’s health

SIBO can mask other conditions and postpone the necessary treatment. So, timely detection and testing of SIBO is crucial.


For years IBS was thought to originate from the mind but today it’s understood that gut conditions like SIBO can lead to IBS symptoms. Several trials showed that targeting gut microbes had a positive effect on IBS, supporting the link between bacterial growth and IBS.

SIBO and IBS-bacteria-intestines

Irritable bowel syndrome (IBS) is a common medical condition that includes symptoms like bloating, abdominal pain and discomfort, and irregular bowel movements. These symptoms are similar to that of SIBO. Also, studies have shown that antibiotic treatment for SIBO showed a small but significant improvement in IBS symptoms, like decreasing abdominal pain in around 40% of the cases, thus confirming the link between the two. Based on these observations, several scientific studies started exploring the link between SIBO and IBS. Most studies confirm that SIBO is more common among people with IBS than healthy people. Also, various studies have shown that SIBO is more common in IBS-diarrhea subtype than in other subtypes. Therefore, ​​SIBO testing is especially important in diarrheal IBS than in other types of IBS.


As studies have indicated, the prevalence of SIBO in IBS patients is significantly higher compared to healthy controls. And there are some risk factors that increase the probability of developing SIBO among IBS patients. These factors include gender, age, certain symptoms and subtypes of IBS. The likelihood of IBS patient having SIBO increases if:

  • You’re a female
  • You’re over 55  (over what age specifically?)
  • Your major IBS symptoms are bloating and flatulence
  • You have diarrhea subtype IBS
  • You’re taking narcotic drugs prescribed for IBS

Bloating, which is often a symptom in IBS patients, can be related to increased gas production in the gut which often happens in case of SIBO. While more studies are needed to explore this link, IBS patients with bloating, as well as older people with diarrhea-predominant IBS are more likely to have SIBO in addition to IBS. So, if you are diagnosed with IBS or have the above mentioned symptoms and risk factors, SIBO testing can answer many of your questions and help you relieve the symptoms.


If you have symptoms like watery diarrhea, flatulence, abdominal pain and distension, and bloating, you might want to check for SIBO.. If you are already diagnosed with IBS and have SIBO-related symptoms or risk factors, you might also want to cross out SIBO from your list. 

At the Dempster Clinic – Center for Functional Medicine, we offer a simple, non-invasive gastrointestinal test that detects bacterial overgrowth in the small intestine. SIBO testing is conducted through a take-home breath test kit. This test is performed over the course of two to three hours and involves drinking a lactulose mannitol solution.

Once bacterial overgrowth has been detected, intervention strategies involving diet, digestive support, probiotics and antimicrobials can be used to treat the condition. If you are interested in strategies to reduce SIBO symptoms, click here.

​​Successful eradication of SIBO has been shown to reduce bloating, gas, diarrhea, and abdominal pain in patients more effectively than many other treatments for IBS.