SIBO Breath Test (Gut Health)

The SIBO breath test is available at Toronto Centre for Naturopathic Medicine.

SIBO (Small Intestinal Bacterial Overgrowth) is a health condition in which excessive bacteria grow in the small intestine, leading to digestive disturbances and systemic symptoms. Normally, the small intestine has a low bacterial count, but when bacteria overpopulate this area, they interfere with nutrient absorption and digestion.

The SIBO breath test is widely used by naturopathic doctors and integrative and functional medicine practitioners to determine whether an overgrowth of bacteria in your small intestine (i.e., SIBO) may be the cause of your digestive symptoms.

The SIBO breath test assesses:

  • Levels of exhaled hydrogen (produced by digestion of carbohydrates by gut bacteria)
  • Levels of exhaled methane produced by digestion of carbohydrates by gut bacteria)
  • Timing of gas production (i.e., at what approximate location in the intestine the bacterial overgrowth is present)

The SIBO breath test may provide useful guidance if you:

  • have unexplained gastrointestinal symptoms
  • suspect an underlying gut imbalance
  • digestive symptoms that have been resistant to conventional medical treatment
  • have been diagnosed with irritable bowel syndrome (IBS)
  • are considering treatment using a FODMAP diet
  • have been diagnosed with, or are interested in prevention of any of the range of health conditions associated with SIBO

Health conditions associated with SIBO include:

How does the SIBO breath test work?

The SIBO breath test is a simple, non-invasive test that measures hydrogen and methane levels in your breath after consuming a sugar solution.

These gases are produced when excess bacteria in the small intestine ferment the consumed sugar solution, releasing hydrogen and/or methane – gases that are absorbed into the bloodstream, carried to the lungs, and exhaled. If you exhale levels of these gases exceeding reference levels, the conclusion is that you have an overgrowth of hydrogen and/or methane producing bacteria.

SIBO Breath Test Customization

At Toronto Centre for Naturopathic Medicine, the SIBO breath test may be modified based on your health concern or symptoms.

Although older versions of the SIBO breath test may collect only hydrogen, 15% or more persons will produce methane rather than hydrogen with microbial fermentation of carbohydrates, therefore to ensure the most accurate assessment possible, both hydrogen and methane should be measured. All SIBO breath tests at Toronto Centre for Naturopathic Medicine measure both hydrogen and methane.

Testing protocols may require two or three hours to complete. Three hours protocols reduce the probability of misdiagnosis in patients having slow motility. All SIBO breath tests at Toronto Centre for Naturopathic Medicine employ a three hour protocol.

In selecting a sugar solution to use in SIBO breath testing, it is important to know that glucose is completely absorbed in the first section of the small intestine, and lactulose is absorbed throughout the entire small intestine and into large intestine. A lactulose-only assessment is the most affordable option; a lactulose + glucose assessment is the most thorough option.

This test protocol can be employed using a fructose sugar solution to assess “carbohydrate malabsorption”, in which sugars are poorly digested before they reach the large intestine, resulting in severe “gassiness”. This may identify the cause of severe IBS symptoms.

Testing options include:

  • Lactulose-only SIBO breath test
  • Glucose-only SIBO breath test
  • Lactulose + glucose SIBO breath test (testing protocol is repeated using each sugar solution)
  • Fructose-only carbohydrate malabsorption breath test

Our SIBO breath tests are provided by University Health Network (UHN) and St. Mary’s General Hospital (Waterloo Regional Health Network).

Learn more about SIBO breath testing.

Sample Report
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Other tests available at Toronto Centre for Naturopathic Medicine that offer a deeper understanding of the underlying causes of your digestive symptoms, including symptoms of irritable bowel syndrome, Crohn’s disease and ulcerative colitis include:

References

Simrén M, Stotzer PO. Use and abuse of hydrogen breath tests. Gut. 2006 Mar;55(3):297-303. doi: 10.1136/gut.2005.075127. PMID: 16474100; PMCID: PMC1856094.

deLacy Costello BP, Ledochowski M, Ratcliffe NM. The importance of methane breath testing: a review. J Breath Res. 2013 Jun;7(2):024001. doin:10.1088/1752-7155/7/2/024001.

Hydrogen breath test. [Internet]. Cleveland Clinic; [cited 2025 Jul 29]. Available at: https://my.clevelandclinic.org/health/diagnostics/12360-hydrogen-breath-test

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