SIBO Diagnosis: Positive Breath Test

1. Introduction to the SIBO Breath Test
2. What is SIBO und how is it diagnosed?
3. Preparation for the SIBO Breath Test
4. Conducting the SIBO Breath Test
5. Types of Sugars for SIBO Testing
6. Interpretating the Test Results
7. Special Case: Hydrogen Sulfide SIBO
8. Sources of Error in the SIBO Breath Test
9. Treatment Options for a Positive SIBO Breath Test
10. Conclusion: Key Information About the SIBO Breath Test for Patients and Professionals

The SIBO breath test is an essential tool for identifying conditions such as Small Intestinal Bacterial Overgrowth (SIBO), especially in patients showing symptoms similar to IBS, like bloating, abdominal pain, gas, diarrhea, or constipation. Bacteria in the small intestine can produce hydrogen or methane or hydrogen sulfide which can cause those symptoms.

1. Introduction to the SIBO Breath Test

The SIBO breath test is a crucial tool for diagnosing small intestinal bacterial overgrowth. The test detects elevated levels of hydrogen or methane in the breath, which are produced by bacteria fermenting specific foods in the small intestine. As a simple, non-invasive testing method, it is a valuable approach to assess gut health. By measuring hydrogen and methane levels in the breath after the intake of different sugars, bacteria in the small intestine can be identified. The simple administration of the test, without blood sampling or invasive procedures, makes it a well-tolerated option. The laboratory carefully analyzes the breath samples to ensure accurate results. In the case of a positive result, targeted therapeutic measures are important to restore balance in the gut. The insights gained from a SIBO breath test can help tailor individual treatment plans in the context of irritable bowel symptoms.

2. What is SIBO und how is it diagnosed?

SIBO refers to an overgrowth of bacteria in the small intestine. It is one of the most commonly overlooked conditions, often mistaken for IBS. The breath test is the primary diagnostic method. After ingesting test sugars such as lactulose, glucose, or fructose, patients exhale into collection tubes. If bacteria are present, they produce hydrogen, methane, or hydrogen sulfide, which appear in the breath. A positive result—typically an increase of 20 ppm hydrogen or 10-12 ppm methane—suggests SIBO.

3. Preparation for the SIBO Breath Test

Accurate breath testing requires proper preparation to avoid false positives or misleading results. Patients must avoid antibiotics for 4 weeks and gas-producing foods for at least 24–72 hours. A low-FODMAP diet is recommended the day before testing to minimize fermentation. Fasting for 8–12 hours before the test is mandatory. Following these instructions ensures reliable levels of gas are recorded and avoids negative effects on diagnostic accuracy.

To ensure the most accurate results from a SIBO breath test and identify the dominant bacteria in the small intestine, several key precautions should be followed before the test by the patient. These include:

• No antibiotic use for 4 weeks before the test (1,2),
• No prokinetics or laxatives for at least 1 week before the test,
• Avoiding gas-producing foods for 3 days before the test,
• No prebiotics or probiotics for 1 day before the test (1),
• No fermentable complex carbohydrates (e.g., lentils, beans, cabbage, whole grains, etc.) for 1 day before the test (3)
• Following a low-FODMAP diet (fermentable oligo-, di-, monosaccharides, and polyols) and easily digestible diet the day before the test,
• Avoiding smoking (3), chewing gum, and alcohol consumption the day before the test,
• Fasting for 8–12 hours before the test (1,2,3),
• Brushing teeth on the morning of the test with sorbitol-free toothpaste or without toothpaste,
• Avoiding the use of denture adhesives on the test morning,
• Refraining from smoking, eating, and engaging in excessive physical activity during the test (1,2),
• Drinking only small amounts of water during the test.

Failure to follow these guidelines may lead to inaccurate test results. Permitted foods include eggs, white rice, chicken, lean beef & pork, white bread, unsweetened coffee or tea, and still water. Summary of the presented points:

4. Conducting the SIBO Breath Test

Once the preparations are complete, the SIBO breath test is conducted. The test itself is done in the morning on an empty stomach. Teeth should only be brushed with water, not toothpaste. After taking Lactulose or Glucose, breath samples are collected at regular intervals to analyze fermentation processes in the small intestine. The measured levels of hydrogen and methane provide insight into possible bacteria in the small intestine and their activity. The test usually lasts 3 hours, during which the patient should remain relaxed and avoid physical exertion.

5. Types of Sugars for SIBO Testing

The most common sugars used in testing are glucose and lactulose. Lactulose typically reaches the large intestine after 120 minutes, leading to elevated hydrogen levels in healthy individuals. A rise in gases before this point suggests fermentation in the small intestine, indicative of SIBO. Fructose may also be used, though results can vary due to absorption differences and cases of fructose intolerance.

6. Interpretating the Test Results

After the SIBO breath test, the interpretation of the results is critical. A test is considered positive if hydrogen levels increase by over 20 ppm or methane by over 10 ppm within 90 minutes. These gases are produced by bacteria, not human cells. Interpretation should be done by experienced healthcare professionals. Symptoms reported during the test also provide valuable diagnostic contact points.

According to the North American consensus (4) and European guidelines (5), a breath test is considered positive if:

• Hydrogen rises by more than 20 ppm compared to the baseline within the first 90 minutes (4)
• Methane rises by more than 10 ppm compared to the baseline during the test (4,5)

This should occur after the intake of 75g of glucose (4), 25g of fructose(4), or 10g of Lactulose (4)

7. Special Case: Hydrogen Sulfide SIBO

Hydrogen sulfide SIBO is a unique subtype often missed by standard breath testing. In cases where expected gas increases are absent after 180 minutes, hydrogen sulfide–producing bacteria may be responsible. This form is harder to detect and often requires diagnosis based on symptoms and test pattern interpretation.

8. Sources of Error in the SIBO Breath Test

A high baseline level can indicate a faulty procedure and may require repeating the test.

Other sources of error include slow or fast intestinal transit, short bowel syndrome (e.g., after surgery), celiac disease, or non-responders. Such factors can lead to false-negative or false-positive results, making clinical context crucial.

9. Treatment Options for Positive SIBO Breath Test

A positive result opens the door to several treatment approaches, including targeted antibiotics, herbal antimicrobials, and a therapeutic diet. A structured low-FODMAP or Bi-Phasic diet can reduce symptoms and improve gut balance. Treatment should be adapted to the dominant gas type—hydrogen, methane (or IMO), or hydrogen sulfide.

10. Conclusion: Key Information About the SIBO Breath Test for Professionals and Patients

This article outlines how the breath test is a reliable, patient-friendly method to assess bacterial overgrowth in the small intestine. By analyzing elevated gas levels, identifying symptoms, and understanding the foods involved in fermentation, healthcare providers can create effective, individualized treatment plans. With the right contact and support, patients can restore a healthy balance in their gut.

References

1. Hammer HF, Fox MR, Keller J, Salvatore S, Basilisco G, Hammer J, Lopetuso L, Benninga M, Borrelli O, Dumitrascu D, Hauser B, Herszenyi L, Nakov R, Pohl D, Thapar N, Sonyi M; European H2-CH4-breath test group. European guideline on indications, performance, and clinical impact of hydrogen and methane breath tests in adult and pediatric patients: European Association for Gastroenterology, Endoscopy and Nutrition, European Society of Neurogastroenterology and Motility, and European Society for Paediatric Gastroenterology Hepatology and Nutrition consensus. United European Gastroenterol J. 2022 Feb;10(1):15-40. doi: 10.1002/ueg2.12133. Epub 2021 Aug 25. PMID: 34431620; PMCID: PMC8830282.
2. Rezaie A, Buresi M, Lembo A, Lin H, McCallum R, Rao S, Schmulson M, Valdovinos M, Zakko S, Pimentel M. Hydrogen and Methane-Based Breath Testing in Gastrointestinal Disorders: The North American Consensus. Am J Gastroenterol. 2017 May;112(5):775-784. doi: 10.1038/ajg.2017.46. Epub 2017 Mar 21. PMID: 28323273; PMCID: PMC5418558.
3. Saad RJ, Chey WD. Breath testing for small intestinal bacterial overgrowth: maximizing test accuracy. Clin Gastroenterol Hepatol. 2014 Dec;12(12):1964-72; quiz e119-20. doi: 10.1016/j.cgh.2013.09.055. Epub 2013 Oct 1. PMID: 24095975.
4. Rezaie A, Buresi M, Lembo A, Lin H, McCallum R, Rao S, Schmulson M, Valdovinos M, Zakko S, Pimentel M. Hydrogen and Methane-Based Breath Testing in Gastrointestinal Disorders: The North American Consensus. Am J Gastroenterol. 2017 May;112(5):775-784. doi: 10.1038/ajg.2017.46. Epub 2017 Mar 21. PMID: 28323273; PMCID: PMC5418558.
5. Hammer HF, Fox MR, Keller J, Salvatore S, Basilisco G, Hammer J, Lopetuso L, Benninga M, Borrelli O, Dumitrascu D, Hauser B, Herszenyi L, Nakov R, Pohl D, Thapar N, Sonyi M; European H2-CH4-breath test group. European guideline on indications, performance, and clinical impact of hydrogen and methane breath tests in adult and pediatric patients: European Association for Gastroenterology, Endoscopy and Nutrition, European Society of Neurogastroenterology and Motility, and European Society for Paediatric Gastroenterology Hepatology and Nutrition consensus. United European Gastroenterol J. 2022 Feb;10(1):15-40. doi: 10.1002/ueg2.12133. Epub 2021 Aug 25. PMID: 34431620; PMCID: PMC8830282.