Testing for Small Intestinal Bacterial Overgrowth (SIBO)

Dr. Heidi Lescanec, ND

SIBO TESTING:  The Hydrogen and Methane Breath Test

We can now diagnose and assess SIBO through a breath test. When some bacteria digest foods, they produce gases. Only bacteria, not humans, produce hydrogen and methane as metabolic by-products (1). You may be familiar with breath testing as it is used in labs now to determine if there is an H. Pylori infection in the stomach. Currently the availability of breath testing for SIBO in Canada is limited to hospital and university research labs.

At Sage Clinic, we now have a special machine to do SIBO testing called a Quintron Breathtracker. This machine measures the 2 gases (Hydrogen and Methane) that SIBO bacteria produce. Tests are done at home with a special SIBO kit that can be obtained from the clinic. The breath samples are collected by exhaling into a special tube, which stores the labeled sample until it is returned to Sage Clinic for lab analysis. We can also receive and process out-of-town samples.

How does this test work?

In the morning after waking, you collect a fasting baseline specimen. Next a solution of lactulose – an unabsorbable synthetic sugar – is taken as a drink. This sugar is the “fuel” for bacterial fermentation. Lactulose is non-absorbable because humans do not produce the enzymes to digest it, only bacteria do. It takes the lactulose approximately 2 hours to traverse the small bowel. Serial breath specimens are then taken by exhaling into a special tube, every 20 minutes, for 3 hours total.

Where is the test done and what preparation is required?

You do the collection in the comfort of your home after following a 24-hour prep diet and an overnight fast. Certain medications need to be avoided for a period of time before the test. Antibiotics and Antifungals should not be used for at least 2 weeks prior to an initial test; and PPI (Proton Pump Inhibitors) should not used.

What is the Prep Diet?

A typical preparation diet is limited to white rice, fish/poultry/meat, eggs, clear beef or chicken broth (not bone broth or bouillon), oil, butter, salt, and pepper and weak coffee and tea with no sugar or milk/cream or dairy substitute.

What is the purpose of the Prep diet?

We use this diet only to get a clear reaction to the test solution by reducing fermentable foods the day before.   This is not a “healthy” diet or a “treatment” diet. It is ONLY a test prep diet. In cases where a person is constipated, two days of prep diet may be needed to reduce baseline gases to negative.

What determines a SIBO positive test?

The interpretation of a positive or negative test result is made by an evaluation of the levels of the two gases as well as the timing of when these gas levels rise.

Why can’t you test a stool sample?

A stool sample will mainly show bacteria from the large intestine (colon) which always has MANY bacteria in it, and is not the location of the “problem” with SIBO.

Why can’t you culture bacteria from the small intestine?

You cannot collect samples from the SI without contaminating the instrument used to collect them –ie. the instrument would first pass through the mouth and the throat where it would pick up bacteria from these ”earlier” sites before reaching the small intestine. Another reason is that the bacteria that live in our gut are anaerobes meaning they die as soon as they are exposed to oxygen. (2)


  1. Siebecker, Allison and Steven Sandberg-Lewis, Small Intestine Bacterial Overgrowth: Often-Ignored Cause of Irritable Bowel Syndrome Townsend Newsletter 2013; 02/03:1-4
  2. Pimentel, Mark. A New IBS Solution: Bacteria – The Missing Link in Treating Irritable Bowel Syndrome. Health Point Press, 2011