Hydrogen Increase Over Baseline by 90 Minutes – SIBO Breath Test Marker The "Hydrogen increase over baseline by 90 minutes" is a critical marker designed to detect abnormal fermentation in the small intestine. During this test, patients ingest a sugar substrate (typically lactulose), and breath samples are collected over a 2-hour period to measure hydrogen and methane gas levels produced by bacteria. In a healthy digestive tract, minimal hydrogen is produced in the small intestine, as most bacteria reside in the large intestine. However, a rise in hydrogen of ≥20 parts per million (ppm) above baseline within 90 minutes strongly suggests the presence of SIBO, where excess bacteria ferment carbohydrates prematurely in the small intestine—leading to symptoms like: Bloating Abdominal discomfort Excessive gas Diarrhea or loose stools Nutrient malabsorption This marker helps differentiate hydrogen-dominant SIBO from other digestive disorders and guides targeted treatment using antimicrobial herbs, antibiotics, or dietary strategies like the low FODMAP diet. Why It Matters An early hydrogen rise is a hallmark of bacterial overgrowth in the small intestine, not the colon. Identifying this pattern allows clinicians to address the root cause of chronic digestive symptoms, reduce inflammation, restore gut balance, and improve long-term gastrointestinal health.
Small Intestinal Bacterial Overgrowth (SIBO)
What is small intestinal bacterial overgrowth (SIBO)?
SIBO is the accumulation of 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.
What is the small bowel?
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.
What is a hydrogen and methane breath test for small intestinal bacterial overgrowth?
The Hydrogen and Methane Breath Test for SIBO 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, 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 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. Our SIBO breath test can be administered in-office or in the comfort of the patient’s own home.
Biomarkers in this category
2 biomarkers · optimal ranges shown
Peak Methane (CH4) Production – SIBO Breath Test Marker Peak Methane (CH4) Production is a critical marker in NutriPATH’s 2-Hour SIBO Breath Test, used to detect methane-producing microbes in the small intestine, particularly methanogenic archaea such as Methanobrevibacter smithii. Unlike hydrogen, which is produced by bacteria fermenting carbohydrates, methane is formed when certain archaea consume hydrogen and convert it into methane gas. A methane level of ≥10 parts per million (ppm) at any point during the 2-hour breath test is considered a positive result for methane-dominant SIBO or Intestinal Methanogen Overgrowth (IMO). High methane levels are commonly associated with constipation-predominant symptoms, including bloating, abdominal discomfort, slowed motility, and hard stools. Methane has been shown to slow intestinal transit time, making it a key contributor to chronic constipation and related disorders such as IBS-C. Identifying peak methane production helps practitioners tailor treatment strategies using specific antimicrobials or combination therapies targeting methanogens, often requiring different interventions than those used for hydrogen-dominant SIBO. Recognizing elevated methane also supports a more accurate diagnosis and enables effective symptom resolution through personalized gut health protocols.