The SIBO breath test is a non-invasive test which measures the level of hydrogen and methane that you breathe out after the ingestion of either glucose or lactulose solution. The test requires you to blow into a test tube through a straw or into a foil bag. This will provide the baseline reading. Afterwards, you will drink a solution containing either lactulose or glucose within 2 minutes. A breath sample is then taken every 15 minutes between 2 – 3 hours.

The whole purpose of the test is to take a snapshot of how the bacteria in the small intestine are functioning within a 3-hour window. When bacteria digest the food they produce gas. These gases pass through the intestinal wall into the bloodstream; transported to the lungs. The expired breath is collected and tested for levels of hydrogen and methane.

Testing can be done by using either a lactulose or glucose breath test

Lactulose Breath Test

Lactulose Breath Test is the preferred choice amongst most practitioners. The reason behind this is due to the fact that lactulose is a carbohydrate that is poorly absorbed. So it travels through the entire gastrointestinal tract making it the perfect substrate to test for bacterial overgrowth. However, it is known to produce more false positives than the Glucose Breath Test. This happens when you are told you do have SIBO but you actually don’t have SIBO.

Glucose Breath Test

Glucose is a sugar that is absorbed in the upper (proximal) part of the small intestine. A positive test will only be presented if the bacterial overgrowth manages to reach the upper part as it mainly occurs closer to the large intestine (distal part of the small intestine). This test is preferred by the scientific literature due to its strict guidelines. Whilst the Lactulose Breath Test is prone to false positives, the Glucose breath is prone to false negatives. This happens when you are told you don’t have SIBO but you actually do have SIBO.

The best way to understand whether you have SIBO is to test using both solutions.

SIBO Breath Test Interpretation

A positive SIBO test for hydrogen is considered when there is a rise above 10ppm of hydrogen within 60 minutes or 20ppm of hydrogen within 90 minutes. The reason why there are two cut-off values depends on which part of the world you carry out the test. 60 minutes is the cut-off period in Europe and 90 minutes is the cut-off period in North America.

Interpreting a SIBO test result is not as straightforward as it seems, other factors must be considered. For instance, a reading above 10ppm at 60 mins does not necessarily mean the test result is positive. The result may show a very high ppm from the beginning of the test. If this is the case, this means that you may not have followed the diet, fast or preparation correctly. A SIBO test result showing no hydrogen peak after 90 minutes, potentially means slow gastrointestinal transit or production of hydrogen sulfide.

The importance of working with a practitioner skilled in interpreting SIBO breath tests is vital in getting the correct treatment. There is not a one size fits all approach to treatment.

SIBO Lactulose Test Result

The above test result indicates that the patient is hydrogen positive according to European and North American guidelines.

How do you order a SIBO test?

You can order a SIBO test at various functional testing labs online. If you receive a positive SIBO result, we do offer a 16-week SIBO Breakthrough Programme at the SIBO Clinic to help you manage your SIBO.