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  • Writer's pictureDr. Randi Brown, ND

Why "Managing" IBS is Not Enough. Finding the SIBO within the IBS.

Updated: Nov 25, 2023

IBS is a Common, Disruptive Condition.

An estimated 20% (or more) of Canadians are affected by IBS. That's nearly 1 in 5. Now before we brush IBS off as just having an "upset" or "sensitive tummy", studies on IBS show that nearly 50-70% of IBS patients indicate that their symptoms interfere with everyday life and report missing work or school due to IBS. Additionally, over half also experience fatigue, anxiety, and depression. If that is not enough to stress the impact that IBS has on people's lives, then consider this; 

IBS patients say they would give up 25% of their remaining life (15 years) to live symptom-free.

In other words, their IBS symptoms are so severe and disruptive, they would be willing to make their life shorter by 15 years, just to no longer have IBS. Its past time to look at some answers.

What Defines "Irritable" Bowels?

IBS, by definition, is a functional gastrointestinal "syndrome" meaning its essentially a constellation of signs and symptoms without a particular underlying organic (structural) cause. IBS is characterized by abdominal pain, and changes in stool frequency and form (appearance).  The trouble of leaving a diagnosis entirely up to symptoms is the chance of misdiagnosing or missing another condition entirely that could help explain these very unspecific digestive symptoms. In fact, research is now starting to understand that this may be the case for many.

Recent studies have now shown that up to 20-40% of patients with IBS may actually have what is called Small Intestinal Bacterial Overgrowth, aka "SIBO". That would mean of the 7.5 million people in Canada affected by IBS, nearly 1.5 million of those will in fact have SIBO (as indicated by positive breath tests or other diagnostic methods).

SIBO is an imbalance of the regular bacteria within the small intestines that can lead to symptoms of IBS such as abdominal pain, bloating, gas, cramping, diarrhea, and constipation. As you can see, IBS and SIBO have many overlapping symptoms, making them difficult to distinguish based on symptoms alone, though bloating and flatulence (gas) seem to stand out more predominantly in SIBO patients. 

Figure 1. The SIBO within the IBS. Twenty-to forty percent of IBS patients have positive SIBO breath tests indicating SIBO may be the underlying cause of their symptoms. Roughly ninety percent of SIBO patients come from chronic pancreatitis patients and IBS-diagnosed patients.

Why is it Important to Distinguish Between IBS and SIBO? 

Well, first we have to recognize that IBS is considered a chronic (long-term) condition. While we do have certain medications and supplements that can help manage the symptoms of IBS, such as laxatives for constipation or antispasmodics for cramping, they don't come without financial costs or side effects. Also, those who choose complementary strategies such as CBT, exercise, and dietary changes are committing to long-term lifestyle changes that take time, effort, and education. Also, there are potential harms of following restrictive diets, including the development of nutrient deficiencies leading to other health problems. 

Additionally, SIBO (masked by IBS) that is left untreated and undetected is not inert.

SIBO has been shown to contribute to intestinal inflammation, increase intestinal permeability or "leakiness" of the gut, promote immune activation, and other systemic complications. As well, the altered microbial imbalance in the small intestine can cause malabsorption - leading to troubles breaking down fats and fat-soluble vitamins causing deficiencies in Vitamins  (A, D, E, K), as well as vitamin B12 and Iron resulting in fatigue, anemia, poor concentration or brain fog and neurological disturbances.

SIBO has also been associated with many chronic conditions such as interstitial cystitis, fibromyalgia, acne rosacea, and restless leg syndrome, and a number of studies have shown improvements in these conditions upon successful treatment of SIBO. Because of these associations, it is worth differentiating SIBO from IBS and therefore finding alternative solutions and treatment options.

Figure 2. The development and consequences of SIBO. Once SIBO develops the imbalance and overgrowth of the intestinal flora contribute to immune activation, intestinal inflammation, fermentation and malabsorption of nutrients, and ultimately IBS-like symptoms, and systemic complications.

Different Conditions, Different Treatments

Of the most important reason, to distinguish IBS from SIBO is because, unlike IBS, SIBO has an established effective treatment. The most common treatment for SIBO is pharmaceutical antibiotics. Successful eradication of SIBO and symptoms such as pain, gas, and bloating can be achieved in roughly 50-70% of patients within a single (10 to 14-day) round of antibiotics. There is some research for the use of herbal antimicrobials in the treatment of SIBO as well, however less robust than the pharmaceutical options. As compared to the chronic symptom management of IBS, a short course of antibiotics seems like a reasonable approach for those who have IBS-like symptoms and breath test-positive SIBO results. 

IBS-Subtypes and Intestinal Bacteria Present

What is even more fascinating about the IBS, SIBO connection is that IBS subtypes seem to correlate with SIBO breath test result findings.

  • For instance, IBS-D (diarrhea-predominant) patients are more likely to have high hydrogen gasses on SIBO breath tests,

  • as compared to IBS-C (constipation-predominant), who tend to have methane predominant gasses.

It has been postulated that the hydrogen gasses created by bacterial fermentation of carbohydrates in the gut may have an osmotic laxative effect, helping explain the loose stools and diarrhea. On the other hand, higher levels of methane gasses in the intestines have been thought to have a disruptive effect on the enteric (the gut) nervous system that controls the proper movement of the intestines, ultimately slowing the gastrointestinal tract causing constipation. This is another reason it is important to test for SIBO in IBS patients, as the results of the test itself will help guide the best specific treatment plan while reducing repeated antibiotic use. 

Summary and Review of the IBS-SIBO Connection: 

  1. IBS and SIBO have many symptom overlaps, mainly abdominal pain, changes in bowel movements and stool form, and bloating and flatulence (gas). 

  2. Research has shown that 20-40% of patients with IBS test positive for SIBO via breath test or small intestinal aspirate and culture. 

  3. Not identifying and treating SIBO in IBS patients may cause harm via microbial-induced intestinal inflammation, immune activation, malabsorption, and nutrient deficiencies. 

  4. Unlike IBS, SIBO treatment does not have to be long-term but rather can improve drastically with a single course of antibiotics 

If you have been suffering from a chronic digestive condition, or have been diagnosed with IBS, its time we take a closer look at what's truly "irritating" your bowels. 

Contact me for details, or book a complimentary meet and greet to ask any questions you may have!! 

Dr. Randi Brown | Naturopathic Physician


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