Breath testing for SIBO and gut disorders

Each year on May 29^th, World Digestive Health Day emphasizes the importance of gastrointestinal health. It also provides an opportunity to consider how innovation continues to enhance the diagnosis of digestive problems.

Image Credit: H_Ko/Shutterstock.com

Over the last two years, Melissa Dooley has contributed to Bedfont^® Scientific's World Digestive Health Day articles.

In 2024, the author investigated the significance of organized investigation and the hazards of self-diagnosis in digestive health.¹ In 2025, Bedfont^® investigated the science behind hydrogen-methane breath testing (HMBT)² and its application in detecting small intestinal bacterial overgrowth (SIBO) and carbohydrate malabsorption.

In 2026, Bedfont^® is considering advancements in HMBT and non-invasive gut diagnostics, including the GastroCH₄ECK^®.

The evolution of HMBT

Historically, SIBO diagnosis was based on jejunal aspirate culture. This is an invasive, technically demanding, and impractical technique in routine care that can be expensive.

Though early acceptance was hampered by a lack of standardization, breath testing has evolved as a patient-friendly method for identifying small intestine bacterial overgrowth and carbohydrate malabsorption.

The North American Consensus, published in 2017, established recommendations for preparation processes, substrate dose, and diagnostic criteria.³

This was confirmed by the American College of Gastroenterology (ACG) Clinical Guideline in 2020, which formally recognized breath testing as a therapeutically suitable tool for some patients.⁴

These publications transformed breath testing into a validated, systematic diagnostic approach (provided that testing is performed using recommended protocols, dependable analyzers, and suitably trained practitioners).

Standardization in clinical practice

According to breath testing literature, HMBT must be performed following specified preparation techniques and analyzed in a clinical setting.³

Importantly, device accuracy and reliability play a key role in reducing variability. Sensor technology and calibration systems have advanced, increasing consistency in clinical settings and boosting user confidence in breath testing as a diagnostic tool.

Expanding access: Clinic and home-based testing

Evidence suggests that home-based breath testing, when accompanied by suitable testing instructions, can achieve high completion and reliability rates.⁵

This facilitates flexibility in both clinic-based processes and home-testing pathways, increasing access to diagnostic investigations while retaining clinical trust.

The following are some examples of commonly asked questions in relation to HMBT:

• Is hydrogen-methane breath testing reliable for identifying SIBO?.

When performed in accordance with accepted protocols and interpreted alongside clinical assessment, breath testing is considered a useful diagnostic tool.

• Why is methane measurement important?

Methane levels ≥ 10 ppm indicate intestinal methanogen overgrowth, which is commonly associated with constipation symptoms.⁴ Measuring methane in addition to hydrogen improves diagnostic precision by identifying individuals whose symptoms cannot be explained just by hydrogen-producing bacterial growth.

• What factors influence diagnostic accuracy?

Recent antibiotics, bowel preparation, motility agents, and dietary non-compliance could all affect the outcomes: adherence to established protocols is important.

Looking ahead, many significant changes are predicted to influence the next generation of breath testing.

• International harmonization of testing protocols: organizations like the British Society of Gastroenterology are expected to provide further advice.⁶
• Better multi-gas detection capabilities could expand beyond hydrogen and methane.
• Improved selection leads to cost-effectiveness and better clinical outcomes.

Conclusion

HMBT has evolved into a structured, consensus-based diagnostic method. Advances in clinical understanding, together with continued innovation in diagnostic technology, have strengthened its utility in detecting SIBO, IMO, and carbohydrate malabsorption.

As World Digestive Health Day 2026 approaches, continued innovation will be critical to improve digestive healthcare globally.

Gastrolyzer^® range of HMBT devices

Gastrolyzer^® instruments, including the Gastro^+™ hydrogen breath testing device and the GastroCH₄ECK^®, have been used to detect gastrointestinal diseases for over 30 years.

The Gastro^+™ is a portable, handheld hydrogen device for rapid and easy breath analysis. Infants and elderly patients who struggle to breathe can have tests performed with a mouthpiece or a facemask.

The GastroCH₄ECK^® is the first HMBT device that offers direct breath testing, allowing users to take a reading on the spot and receive rapid results. It also provides remote testing, which involves collecting breath samples in a breath bag and analyzing them later.

References

1. Bedfont^® Scientific  (2024). World Digestive Health Day 2024: Taking control of your digestive health–Importance of not self-diagnosing - Bedfont Scientific Ltd. Bedfont Scientific Ltd. Available at: https://www.bedfont.com/world-digestive-health-day-2024-taking-control-of-your-digestive-health-importance-of-not-self-diagnosing/.
2. Bedfont^® Scientific (2025). World Digestive Day: Understanding Gut Health and The Power of HMBT - Bedfont Scientific Ltd. Bedfont Scientific Ltd. Available at: https://www.bedfont.com/world-digestive-day-understanding-gut-health-and-the-power-of-hmbt/.
3. Rezaie, A., et al. (2017). Hydrogen and Methane-Based Breath Testing in Gastrointestinal Disorders: The North American Consensus. The American Journal of Gastroenterology, 112(5), pp.775–784. DOI: 10.1038/ajg.2017.46. https://journals.lww.com/ajg/abstract/2017/05000/hydrogen_and_methane_based_breath_testing_in.25.aspx.
4. Pimentel, M., et al. (2020). ACG Clinical Guideline: Small Intestinal Bacterial Overgrowth. The American Journal of Gastroenterology, 115(2), pp.165–178. DOI: 10.14309/ajg.0000000000000501. https://journals.lww.com/ajg/fulltext/2020/02000/acg_clinical_guideline__small_intestinal_bacterial.9.aspx.
5. Pitcher, C. and Otterstad, M. (2022). P301 Common issues with home testing – hydrogen and methane breath testing for SIBO. Poster presentations, pp.A185.2-A186. DOI: 10.1136/gutjnl-2022-bsg.354. https://gut.bmj.com/content/71/Suppl_1/A185.2.
6. Breath, H. (2024). Hydrogen/Methane Breath Testing for SIBO and Malabsorption. British Society of Gastroenterology (BSG). Available at: https://www.bsg.org.uk/clinical-resource/agip-protocol-for-hydrogen-methane-breath-testing.

Acknowledgments

Produced using materials originally authored by Melissa Dooley from GastroLife.

About Bedfont^® Scientific Ltd

Bedfont^® Scientific has specialised in the design and manufacture of exhaled breath and gas monitoring instruments since 1976.

For medical gas monitoring, their Medi-Gas Check medical pipeline testing range verifies not only the quantity but also quality of gas administered to patients.

Bedfont's breath analysers include carbon monoxide (CO) monitors such as the Smokerlyzer^®, used for smoking cessation, and the ToxCO^®, used by emergency services, to diagnose CO poisoning.

The NObreath^® FeNO monitor provides accurate analysis of airway inflammation for the control of asthma, and the Gastrolyzer^® range aids in the detection of gastrointestinal disorders and food intolerances. Quick and non-invasive, breath analysis is the new blood test.

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