The SIBO breath test, a pivotal diagnostic tool in assessing Small Intestinal Bacterial Overgrowth (SIBO), is a non-invasive examination designed to measure the levels of hydrogen and methane gases that individuals exhale following the consumption of either a glucose or lactulose solution. This test involves a carefully orchestrated process to capture a comprehensive snapshot of bacterial activity within the small intestine over a specific three-hour timeframe.
Initiating the test, individuals are required to blow into a test tube through a straw or into a foil bag to establish a baseline reading. Subsequently, they ingest a solution containing either lactulose or glucose within a strict two-minute window. The chosen carbohydrate serves as a substrate for bacterial fermentation, simulating the digestive process that occurs within the small intestine.
The subsequent critical phase involves collecting breath samples at 15-minute intervals throughout the 2 to 3-hour duration post-ingestion. This meticulous timeline enables healthcare professionals to monitor and analyze the production of gases, specifically hydrogen and methane, which are byproducts of bacterial digestion. As bacteria break down carbohydrates, they release these gases, which then traverse the intestinal wall, enter the bloodstream, and ultimately reach the lungs. The gases are then expelled in the breath, forming the basis for analysis during the SIBO breath test.
The fundamental objective of the SIBO breath test is to gain insight into the functioning of bacteria within the small intestine during this specified temporal window. By measuring the levels of hydrogen and methane in the breath samples, healthcare practitioners can detect potential overgrowths of bacteria in the small intestine, contributing to a more accurate diagnosis of SIBO.
It is noteworthy that the choice between a lactulose or glucose breath test depends on various factors, including the patient’s medical history and the healthcare practitioner’s preference. Both tests follow the same procedural framework but utilise different substrates, aiding in the identification of distinct patterns in bacterial fermentation.
Lactulose Breath Test
The Lactulose Breath Test is the preferred choice amongst most practitioners. The reason behind this is 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 don’t have SIBO.
Glucose Breath Test
Glucose is a sugar 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). The scientific literature prefers this test 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. There are two cut-off values depending 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 an SIBO test result is not as straightforward as it seems, other factors must be considered. For instance, a reading above 10 ppm at 60 minutes 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 no one-size-fits-all approach to treatment. We are the only SIBO clinic in the UK which offers the SIBO test interpretation service for only £25.
The above test result indicates that the patient is hydrogen-positive according to European and North American guidelines.