26. Jun, 2018

What is SIBO and how is it treated?

Good gut health starts with supporting greater diversity and numbers of 'good' gut bacteria in the large intestine.

In the small intestine however, an overgrowth known as Small Intestine Bacterial Overgrowth (SIBO) is a sign of a digestive disorder. In this part of our gastrointestinal tract we want less, not more bacteria. 

Due to the fact that it is often a secondary disease, SIBO is difficult to manage and can take years to eradicate, if ever. 

The prevalence among older patients appears to average at just over 10% of the population according to UK studies. For a number of reasons SIBO is difficult to study so we do not have current Australian data. Given our similarities with the U.K population we can assume it would not be too different to that figure here. 

The primary cause is suspected to be a combination of decreased small intestine motility (muscular movement), bile acids and pancreatic enzymes.    

There are disease states that we know can lead to SIBO (secondary disease) and can be treated: 

  • Active small bowel inflammation (eg Coeliac, Crohns)
  • Adhesive disease
  • Collagen vascular disease
  • Diabetic enteropathy
  • Gut dysmotility
  • Small bowel diverticular disease
  • Small bowel stricturing disease (eg Crohns, NSAIDs) 

Common symptoms overlap with those of IBS and include:

  • Bloating
  • Diarrhoea
  • Fatigue
  • Malnutrition
  • Nausea & vomiting
  • Vitamin (esp. A, D, E, K & B12) & mineral (esp. calcium, iron, magnesium) deficiency
  • Weight loss 

In addition, because of brush border inflammation, fructase and lactase (enzymes that break down fructose and lactose respectively) deficiency may develop as a result of SIBO. 

Diagnosis is usually via the non-invasive Hydrogen Breath Tests where patients drink a lactulose or glucose solution. The resulting hydrogen or methane, which can only be produced by bacteria present in the small intestine, is measured. Your GP or gastroenterologist will interpret the results. 

We know the following increase your risk of developing SIBO:

  • Aging
  • Alcoholism
  • Chronic antacid/PPI use (leads to gastric achlorhydria)
  • Coeliac Disease
  • Gastroparesis (slow emptying of the stomach)
  • GI infections 

Treatment is with antibiotic therapy for 14 days, followed by a repeat breath test and some dietary changes to address possible nutritional deficiencies and minimise symptoms. 

The low-FODMAP diet is clinically proven to help manage IBS in around 70% of sufferers. Carbohydrate intolerance is common among patients with SIBO, and the Low-FODMAP diet may therefore be very helpful. Other possible treatment diets are based on anecdotal evidence and include GAPS (Gut & Psychology Syndrome diet) and SCD (Specific Carbohydrate Diet). 

As with all diets, the choice of which is best suited depends on the patient, and should be personalised by your nutritionist. 


American Chemical Society 2018, Digestion illustration, <http://www.acs.org/content/dam/acsorg/education/resources/highschool/chemmatters/food/digestion-illustration.jpg>

Dukowicz, AC, Lacy, BE & Levine, GM 2007, 'Small Intestinal Bacterial Overgrowth: A Comprehensive Review', Gastroenterology & Hepatology, vol.3, no.2, pp. 112-122. 

Ford, AC, Spiegel, BMR, Talley, NJ, & Moayyedi, P 2009, 'Small Intestinal Bacterial Overgrowth in Irritable Bowel Syndrome: Systematic Review and Meta-analysis', Clinical Gastroenterology and Hepatology, vol.7, no.12, pp.1279-1286. 

Rezaie, A, Pimentel, M & Rao, SS 2016, 'How to Test and Treat Small Intestinal Bacterial Overgrowth: an Evidence-Based Approach', Current Gastroenterology Report, vol.18, no.8. 

Sachdev, AH & Pimentel, M 2013, 'Gastrointestinal bacterial overgrowth: pathogenesis and clinical significance', Therapeutic Advances in Chronic Disease, vol.4, no.5, pp.223-231.