Tag: SIBO

Common Breath Test Results Part 1: SIBO

Posted on by Bradley Bush

SIBO (small intestinal bacterial overgrowth) breath testing measures the production of hydrogen and methane gases by bacteria in the gut. These breath test results offer important insights into bacterial overgrowth.  First, individuals ingest glucose or lactulose, which are fermented by bacteria in the small intestine. By assessing the changes in gas production during the breath test, SIBO can be diagnosed. This article is part one of a three-part series discussing common trends and diagnostic criteria for both glucose and lactulose breath testing.

Glucose Breath Test Results

Glucose is absorbed in the small intestine relatively quickly, making it an excellent substrate for detecting bacterial overgrowth in the upper part of the small intestine.

Positive Glucose SIBO Breath Test Results (Hydrogen or Methane Elevation within 120 minutes)

  • Hydrogen Rise: An increase in hydrogen gas of 12 ppm or more within the first 120 minutes meets the diagnostic criteria for SIBO (Figure 1). This indicates that bacteria in the small intestine are fermenting glucose before it can be fully absorbed.

    Graph showing positive SIBO results
    Figure 1: Hydrogen Rise: An increase in hydrogen gas. Glucose is mostly absorbed in the small intestines therefore the increase in gas is from bacteria.
  • Peak Methane Levels: A peak methane level of 10 ppm or more within 120 minutes suggests the presence of methane-producing bacteria in the small intestine, meeting the criteria for SIBO (Figures 2 & 3). Methane-producing bacteria are often associated with constipation.
    Graph showing increasing levels of methane on SIBO test
    Figure 2 Peak Methane Level: Methane gas activity achieves a level of more than 10 ppm from 60-180 minutes of the test. This indicates the presence of methane producing bacteria and SIBO.Graph showing elevated methane levels on a SIBO test

    Figure 3 Peak Methane Level: Methane gas activity elevated throughout test (baseline to 180 minutes).

  • Combined Hydrogen + Methane Rise: An increase in the combined total of hydrogen and methane gas of 12 ppm or more within the first 120 minutes meets the diagnostic criteria for SIBO (Figure 4). This indicates bacteria in the small intestine ferment the glucose before it can be fully absorbed.
    Graph showing positive SIBO results based on combined gas levels
    Figure 4 Combined Hydrogen + Methane Rise: A rise in the combined total of hydrogen and methane gas of 12 ppm (glucose)/ 15 ppm (lactulose) or more within the first 120 minutes meets the diagnostic criteria for SIBO. This is an example of a positive glucose breath test result.

     

Negative Glucose SIBO Breath Test Results

In healthy individuals, glucose absorbs before it reaches the large intestine, and there is no significant rise in hydrogen or methane within the first 120 minutes (Figure 5). Gas production occurring after 120 minutes reflects normal fermentation in the large intestine.

graph showing negative SIBO test
Figure 5 Negative SIBO: No significant increases in hydrogen gas, methane levels below 10 ppm, and insignificant levels of combined gases indicates negative breath test results.

 

Lactulose Breath Test Results 

Lactulose is not absorbed by the body and passes through both the small and large intestines, making it useful for detecting bacterial overgrowth in both regions. 

Lactulose Positive SIBO Breath Test Results (Early Hydrogen or Methane Rise within 120 minutes)

  • Hydrogen Rise: A hydrogen increase of 20 ppm or more within the first 120 minutes meets the diagnostic criteria for SIBO, indicating fermentation in the small intestine by bacteria (Figure 6).graph showing a positive lactulose breath test resultsFigure 6 Hydrogen Rise: An increase in hydrogen gas. Lactulose is not absorbed in the intestines. Therefore, large intestinal bacterial fermentation is observed (typically 140-180 minutes).
  • Peak Methane Levels: A peak methane level of 10 ppm or more within 120 minutes suggests the presence of methane-producing bacteria in the small intestine. This meets the criteria for SIBO (Figures 2 & 3). Methane-producing bacteria are often associated with constipation.
  • Combined Hydrogen + Methane Rise: An increase in the combined total of hydrogen and methane gas of 15 ppm or more within the first 120 minutes meets the diagnostic criteria for SIBO (Figure 4). This indicates bacteria in the small intestine ferment lactulose. 

Lactulose Negative SIBO Breath Test Results

In a negative test, there will be no significant gas rise in the first 120 minutes. Additionally, gas production typically rises after this period, reflecting normal lactulose  fermentation within the large intestine (Figure 5).

Common Trends in Hydrogen and Methane Gas Production

  • Hydrogen-Dominant SIBO: Patients with diarrhea-predominant symptoms (IBS-D) often show elevated hydrogen levels. A sharp rise in hydrogen gas, particularly early in the breath test, suggests bacterial fermentation of glucose or lactulose in the small intestine. (Figures 1 & 6)
  • Methane-Dominant SIBO: Patients with constipation-predominant symptoms (IBS-C) usually present with elevated methane levels. High methane gas, especially when peaking at 10 ppm or more within 120 minutes, indicates the presence of methanogenic archaea. The presence of these bacteria can slow intestinal transit. (Figures 2 & 3)
  • Mixed Hydrogen and Methane Production: Some patients may show elevated levels of both hydrogen and methane gases, leading to a mix of symptoms such as alternating diarrhea and constipation. This pattern can indicate the presence of both bacterial overgrowth and methanogens in the small intestine. (Figure 4)
  • Double Peak Patterns:  For lactulose, a double peak may be observed. If SIBO is present, the first peak occurs within 120 minutes due to small intestinal fermentation. As lactulose reaches the colon, fermentation by colonic bacteria cause the second peak (Figure 7). Double peak results used to be diagnostic for SIBO but are not anymore due to improvements in testing methodology. However, double peaks seen on testing can assist in differentiating between small and large intestine specimen assessments. 

    graph showing a double peak in a lactulose breath test result
    Figure 7: Classic double peak observed during a lactulose breath test. Two distinct rises in gas levels during the breath test are observed. The first peak occurs when bacteria in the small intestine ferment the lactulose. The second peak happens as lactulose reaches the colon where colonic bacteria begin their fermentation process.

Conclusion

Both glucose and lactulose are good substrates for SIBO breath testing. For glucose breath tests, a rise in hydrogen levels or combined gases of 12 ppm or more within 120 minutes meets the criteria for diagnosing SIBO. For lactulose breath tests, hydrogen levels rising by 20 ppm or more or 15 ppm (combined gases) within 120 minutes also indicate SIBO. Peak methane levels of 10 ppm or more indicate methane-dominant SIBO. These tests help clinicians distinguish between hydrogen-dominant and methane-dominant SIBO, leading to more targeted treatment plans.

This is the first blog in a three-part series. Part 2 discusses fructose, lactose, and sucrose sugar malabsorption patterns. In part 3, learn about atypical breath test patterns.

New Clinical Tool: Total SIBO Bacterial Load Measurement

Posted on by Melissa Zinda

Breath testing is a non-invasive diagnostic tool shown to be effective for diagnosing a number of conditions including Small Intestinal Bacterial Overgrowth (SIBO). Gas produced by intestinal bacteria diffuses into the bloodstream, passes through the lungs, and is excreted in the breath where it can be measured. SIBO is characterized by an excessive amount of bacteria in the small intestines, primarily anaerobic fermenting bacteria, that produce measurable gasses such as hydrogen and methane.

 

In the human gastrointestinal (GI) tract, hydrogen and methane gasses are produced by fermenting bacteria as a byproduct of breaking down carbohydrates that have not been fully digested. Bacteria in the gut ferment undigested carbohydrates, releasing atomic hydrogen (H) as a byproduct, which then combines to form molecular hydrogen (H₂). In certain cases, methane gas (CH₄) is produced when methanogenic archaea in the gut utilize hydrogen (H) as a substrate, combining it with carbon dioxide (CO₂) to create methane (CH₄). This process requires atomic hydrogen to first be released during fermentation, making atomic hydrogen a critical precursor for the creation of both hydrogen and methane gasses in the body. 

 

The amount of hydrogen produced in the gut and measured in breath testing, in the forms of H₂ and CH₄, provides data on a person’s bacterial activity. Although there are no published diagnostic criteria using total molecular hydrogen levels to date, it is relevant clinical data that increases the overall functionality of breath test results.

New Clinical Tool for Determining the Total SIBO Bacterial Load

After thousands of SIBO tests, Neurovanna has come to understand the clinical relevance of measuring the total amount of molecular hydrogen produced in both the small and large intestine. The Total SIBO Bacterial Load was developed to help healthcare providers visualize this data and develop more personalized diagnostics and treatment. This unique assessment:

  • Allows for comparisons between optimal and elevated SIBO populations
  • Provides insight into bacterial activity within the large intestine
  • May help predict the potential for die-off reactions to treatments

 

Optimal vs Elevated SIBO Populations

Image showing Total SIBO Bacterial Load graph found on a report

In order to provide clinical value, it is necessary to have ranges with which to compare patient values. Neurovanna generated both optimal and elevated ranges for molecular

 hydrogen from 200 randomly selected breath tests from each diagnostic criteria: glucose SIBO positive, glucose SIBO negative, lactulose SIBO positive and lactulose SIBO negative. As a result, the SIBO breath test reports for both lactulose and glucose include an assessment of the Total SIBO Bacterial Load. Each assessment plots the patient values representing the total molecular hydrogen (H₂) measured for each breath sample against the ranges for the optimal and elevated hydrogen activity over time allowing for comparison between populations. See figure 1.

By comparing the timing and concentration of hydrogen gas in individuals versus a normal population, clinicians can detect fermentation patterns indicative of gastrointestinal abnormalities.

Elevated Bacterial Load in the Large Intestine Indicates Gastrointestinal Abnormalities 

Total hydrogen gas activity can be elevated in the large intestine due to various gastrointestinal abnormalities including: microflora dysbiosis (natural or post-antibiotic), parasitic infections, food maldigestion, food allergies, sugar malabsorption (e.g. lactose intolerance), and disturbances like post-food poisoning or traveler’s diarrhea. Figures 1-5 provide examples commonly seen in SIBO and/or large intestinal bacterial overgrowth (LIBO) positive individuals. Here’s how each of these factors contributes to elevated hydrogen gas.

Dysbiosis and Microflora Imbalances: Dysbiosis, an imbalance of gut bacteria, can cause excessive fermentation of undigested carbohydrates in the large intestine, leading to increased hydrogen gas production. This occurs when harmful bacteria overgrow or beneficial bacteria are reduced, causing disruptions in normal digestion.

Parasitic Infections: Infections from parasites like Giardia can disrupt digestion, causing malabsorption of nutrients. This undigested food reaches the large intestine, where bacteria ferment it, resulting in elevated hydrogen gas levels.

Food Maldigestion: Insufficient production of digestive enzymes (e.g., from pancreatic insufficiency) can lead to undigested carbohydrates entering the colon, where bacteria ferment them, increasing hydrogen gas production.

Food Allergies: Food allergies can cause inflammation in the gut, impairing digestion and leading to malabsorption. As undigested food reaches the large intestine, fermentation by gut bacteria increases hydrogen gas levels.

Lactose Intolerance: In individuals with lactose intolerance, the inability to properly digest lactose results in it reaching the colon undigested. Colonic bacteria ferment lactose, leading to excessive production of hydrogen gas, often causing bloating and discomfort.

Post-Food Poisoning or Traveler’s Diarrhea: Following food poisoning or traveler’s diarrhea, the gut microbiome may be disrupted, leading to malabsorption and bacterial overgrowth. This can result in increased fermentation of carbohydrates in either the small and/or large intestine and elevated hydrogen gas levels.

Graph showing a late rise, positive SIBO result Graph showing a negative SIBO, positive LIBO result

Bacterial Load Predicts Bacterial Die-Off Reactions

 

Hydrogen gas levels can provide insights into the severity of bacterial overgrowth (bacterial load) in SIBO/LIBO and may also be predictive of die-off (Herxheimer) reactions during treatment. 

Hydrogen Gas Levels and Overgrowth Severity

Higher hydrogen gas levels during a breath test can indicate a greater bacterial load in the small intestine. The more bacteria present in the gut, the more fermentation of carbohydrates takes place, resulting in the release of hydrogen gas. In this way, elevated hydrogen levels can reflect the extent of bacterial overgrowth, with higher levels generally suggesting more severe overgrowth.

 

For instance, a rapid and significant rise in hydrogen gas levels shortly after consuming a fermentable substrate (like glucose or lactulose) is often associated with a larger population of hydrogen-producing bacteria, particularly in the small intestine.

 

Predictive of Die-Off (Herxheimer) Reactions

Graph showing a high positive SIBO & LIBO resultHerxheimer reactions or die-off occur when large numbers of bacteria are killed rapidly during treatment (such as with antibiotics or herbal antimicrobials). Patients with higher molecular hydrogen levels, indicating a higher bacterial load, may be at greater risk of experiencing more pronounced die-off reactions during treatment. As more bacteria are killed off in a short period, there is an increased likelihood of releasing toxins into the body, triggering inflammatory responses and worsening symptoms like fatigue, headaches, bloating, and body aches (Figures 1, 3 & 4). 

 

Monitoring hydrogen gas levels before treatment can help predict the intensity of these reactions. Patients with very high hydrogen levels may need a slower introduction to treatment or supportive measures such as detox protocols or liver support, to manage die-off symptoms.

 

While it is difficult to predict exactly how patients will respond to treatment, the total bacterial load can provide some guidance. A general rule is that the higher the total bacterial load, the greater the likelihood of experiencing bacterial die-off (Herxheimer) reactions (Figures 1, 3, & 4). Alternatively, the lower the bacterial load the less likelihood there is of experiencing bacterial die-off (Herxheimer) reactions. For example, the lack of colonic activity shown in figures 2 and 5 suggest a less complicated clinical presentation and greater chance of successful SIBO treatment with lower chance of SIBO recurrence. 

Graph showing a low positive SIBO & LIBO result

Summary

In conclusion, elevated hydrogen gas activity throughout the gastrointestinal tract can result from a variety of factors, including digestion issues, malabsorption, bacterial imbalances, colon diseases, and parasitic infections. Measuring hydrogen gas levels provides valuable insight into the severity of bacterial overgrowth in the small and large intestines and can serve as a predictive tool for treatment-related reactions such as Herxheimer (die-off) responses. Patients with higher hydrogen levels often have a larger bacterial load, which can increase the likelihood of more intense die-off reactions during treatment, underscoring the importance of personalized care to manage symptoms.

Hydrogen gas measurement not only aids in diagnosing SIBO but can also help identify other underlying gut conditions, such as dysbiosis in the large intestine, parasitic infections, or sugar malabsorption disorders like lactose intolerance. Monitoring hydrogen levels can guide healthcare providers in creating a more tailored and holistic treatment plan, which may include additional testing for colon infections, additional support for patients undergoing SIBO treatments, targeted therapies for imbalances, or adjustments to manage food malabsorption. Ultimately, the integration of tools like the Neurovanna Total Bacterial Load provides a deeper understanding of gut health, improving outcomes for patients with SIBO, LIBO, and related gastrointestinal disorders.

The Total SIBO Bacterial Load is unique to Neurovanna. If you are a healthcare provider interested in using non-invasive breath testing to assess SIBO and/or LIBO, set up a Neurovanna account. If you are a patient interested in testing with Neurovanna, ask your doctor to complete this referral form or contact us to find a doctor near you.