SIBO is the accumulation of an excessive amount of gut bacteria in the small intestine (at least 100,000 bacteria per ml of fluid). While bacterium naturally exist throughout the digestive tract, with highest concentrations of bacteria in the colon, a healthy individual should have relatively low levels of bacteria present in the small intestine. Any condition which impairs the normal transit or motion of the small intestine can increase the likelihood of getting SIBO, including lack of adequate stomach acid, damage to the intestine by toxins, or a decrease in the speed at which the small intestine transfers waste to the colon. In the U.S., some research studies have demonstrated that up to 80% of the IBS population, or 36 million individuals, suffer from SIBO.

The small bowel, also known as the small intestine, is the part of the gastrointestinal tract that connects the stomach with the colon. The main purpose of the small intestine is to digest and absorb food into the body. The small intestine is approximately 21 feet in length.

Formally known as Methane SIBO (M-SIBO), Intestinal Methanogen Overgrowth (IMO) is becoming an industry standard term for excessive levels of methane detected during a hydrogen and methane breath test.  There are two main reasons for this change in terminology: 1) methanogens that cause methane gas are technically not bacteria, but are part of the Archaea kingdom, and 2) methanogens typically grow in the colon (large intestine), not the small intestine.

Per the American College of Gastroenterology’s (ACG) Clinical Guidelines on SIBO: “Although methane is increasingly important and recognized, it creates a nomenclature problem in the SIBO framework. For methane, a concentration of ≥10 ppm at any point during the test is indicative of methanogen colonization. However, methanogens are not “bacteria” (representing the “B” in SIBO) but belong to the domain Archaea and may also overgrow in the colon and not just the small intestine. As such, we have proposed a new term, intestinal methanogen overgrowth (IMO), for methanogens rather than SIBO (Figure 1b).”

The Hydrogen and Methane Breath Test for SIBO and IMO is a non-invasive diagnostic tool to identify SIBO and can be administered in the comfort of a patient’s own home. Patients are given a substrate solution to drink, which is a mixture of water and a carbohydrate substrate (lactulose or glucose). After drinking the substrate solution, the patient will collect a series of breath samples by simply breathing into a test tube using a straw. In a healthy individual, one would not expect to see any hydrogen or methane in the breath samples for approximately 90 minutes – 2 hours, the approximate time it would take for the substrate to travel to the small intestine to the colon where, in a healthy system, the substrate would be fed upon by bacteria, thus releasing the hydrogen and methane gas. After ingesting a substrate solution, the patient collects breath samples every 15 minutes over a 2-hour and 15-minute (135 minutes) period. During the hydrogen and methane breath test for SIBO and IMO, the presence of elevated levels of hydrogen or methane gas, or both, identified within 90 minutes of ingesting the substrate solution provides evidence of bacteria or methanogens in the upper region of the digestive tract, i.e. at the level of the small intestine. This excessive build up bacteria is often diagnosed as SIBO while excessive methanogens that cause methane gas is often diagnosed as IMO. Our SIBO and IMO breath test kits can be administered in-office or in the comfort of the patient’s own home.

Glucose is absorbed by the digestive tract so it will not be able to detect SIBO that is further along in the small intestine (proximal jejunum/ileum). However, because of this, glucose is considered to be more sensitive than lactulose, providing less false positives with colonic bacteria.

Lactulose is not absorbed by the digestive tract and will travel through the entire gastrointestinal tract, ultimately providing a complete depiction of all intestinal segments, including the colon (large intestine).