• Digestive discomfort: abdominal pain, bloating or excessive gas after meals.
• Altered bowel habits: constipation, diarrhoea or alternating patterns.
• Carbohydrate intolerance: difficulty tolerating sweet or starchy foods, fibre or certain supplements.
• Unexplained nutritional concerns: anaemia, weight loss or signs of malabsorption or maldigestion.
• Chronic fatigue: tiredness potentially considered in relation to digestive factors.
• IBS-type symptoms: fluctuating digestive patterns that resemble irritable bowel presentations.
• Hypochlorhydria: suspected low stomach acid associated with upper digestive symptoms, including in clients with long-term use of acid-blocking drugs.
• Osteoporosis or low bone density: under review where malabsorption is suspected.
• Unexplained abdominal symptoms: discomfort with no clear cause, especially when linked with bloating.

The Bacterial Overgrowth of the Small Intestine (SIBO) test uses timed breath sampling following ingestion of lactulose to evaluate hydrogen and methane production. These gases are produced when microbes ferment the lactulose substrate, and their concentrations over time can help illustrate fermentation patterns within the small intestine.

This assessment may be clinically useful for practitioners exploring bloating, distension, altered bowel habits, carbohydrate intolerance, suspected malabsorption or upper digestive discomfort. Because gas production patterns can vary over a short time window, a structured 2-hour collection allows practitioners to observe whether fermentation appears to be occurring earlier or more prominently than expected.

SIBO results are typically reviewed alongside symptom timelines, dietary intake, digestive history and other functional assessments. Used in this context, the profile may help guide further discussion around digestive function, contributing factors and practical next steps in a client’s care.

Drinking solution:

Lactulose

3 hour collection

Specimen requirements:

Eight fasting breath samples, taken at baseline, and timed intervals

Average processing time:

10 ±3 days (Confidence: applies to 90% of tests)

Research

• Bures J, Cyrany J, Kohoutova D, et al. Small intestinal bacterial overgrowth syndrome. 2010;16(24).

• Chedid V, Dhalla S, Clarke JO, et al. Herbal therapy is equivalent to Rifaximin for the treatment of small intestinal bacterial Overgrowth. Global Advances in Health and Medicine. 2014;3(3):16–24.

• Dukowicz AC, Lacy BE, Levine GM. Small intestinal bacterial Overgrowth. 2007;3(2).

• Erdogan A, Rao SSC. Small Intestinal Fungal Overgrowth. Current Gastroenterology Reports. 2015;17(4).

• Fasano A. Leaky gut and autoimmune diseases. Clinical reviews in allergy & immunology. 2011;42(1):71–8.

• Gabbard S, Lacy B, Levine G, Crowell M. The impact of alcohol consumption and cholecystectomy on small intestinal bacterial overgrowth. Digestive diseases and sciences. 2013;59(3):638–44.

• Ghoshal UC, Srivastava D, Ghoshal U, Misra A. Breath tests in the diagnosis of small intestinal bacterial overgrowth in patients with irritable bowel syndrome in comparison with quantitative upper gut aspirate culture. European Journal of Gastroenterology & Hepatology. 2014;26(7):753-760.

• Ghoshal UC. How to Interpret Hydrogen Breath Tests. Journal of Neurogastroenterology and Motility. 2011;17(3):312-317.

• Hauge T, Persson J, Danielsson D. Mucosal bacterial growth in the upper gastrointestinal tract in alcoholics (heavy drinkers). Digestion. 2009;58(6):591–595.

• Lauritano E, Gabrielli M, Scarpellini E, et al. Small intestinal bacterial overgrowth recurrence after antibiotic therapy. The American journal of gastroenterology. 2008;103(8):2031–5.

• Levitt MD. Volume and Composition of Human Intestinal Gas Determined by Means of an Intestinal Washout Technic. New England Journal of Medicine. 1971;284(25):1394-1398.

• Lloyd-Still JD, Shwachman H. Duodenal microflora. The American Journal of Digestive Diseases. 1975;20(8):708-715.

• Methodology and Indications of H2-Breath Testing in Gastrointestinal Diseases: the Rome Consensus Conference. Alimentary Pharmacology & Therapeutics. 2009;29:1-49.

• Newberry C, Tierney A, Pickett-Blakely O. Lactulose Hydrogen Breath Test Result Is Associated with Age and Gender. BioMed Research International. 2016;2016:1-5.

• Rana S, Sharma S, Kaur J, Sinha S, Singh K. Comparison of Lactulose and Glucose Breath Test for Diagnosis of Small Intestinal Bacterial Overgrowth in Patients with Irritable Bowel Syndrome. Digestion. 2012;85(3):243-247.

• Rana SV, Bhardwaj SB. Small intestinal bacterial overgrowth. Scandinavian Journal of Gastroenterology. 2008;43(9):1030-1037.

• Roland B, Ciarleglio M, Clarke J, et al. Small intestinal transit time is delayed in small intestinal bacterial Overgrowth. Journal of clinical gastroenterology. 2014;49(7):571–6.

• Saad RJ, Chey WD. Breath Testing for Small Intestinal Bacterial Overgrowth: Maximizing Test Accuracy. Clinical Gastroenterology and Hepatology. 2014;12(12):1964-1972.