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Understanding Double Peak Patterns in Lactulose SIBO Breath Testing

Posted on by Melissa Zinda

When it comes to lactulose breath testing for Small Intestinal Bacterial Overgrowth (SIBO), one of the patterns that may emerge is the double peak. This refers to two distinct rises in gas levels during the breath test. The first peak occurs when bacteria in the small intestine ferment the lactulose. The second peak happens as the lactulose reaches the colon. At this point, colonic bacteria begin their fermentation process. Although this double peak pattern was part of the diagnostic criterion for SIBO, improvements in testing methodology changed how these results are interpreted. While no longer considered definitive for diagnosing SIBO, the double peak still provides valuable insights into the overall health of the digestive system.

The Lactulose Breath Test Double Peak Explained

In a positive SIBO test, lactulose (a non-absorbable sugar) is fermented by bacteria in the small intestine. Within the first 120 minutes of testing, the fermentation causes the first rise or “peak” in hydrogen (H₂) or methane (CH₄) gases. This early gas production indicates excessive bacterial fermentation in the small intestine. As this area typically harbors fewer bacteria than the colon, this peak is considered abnormal. The second peak occurs when the remaining lactulose moves into the large intestine (colon). It is a normal result, reflecting healthy bacterial activity in the colon. However, extreme spikes in activity in the large intestines may indicate overgrowth/ abnormal activity. (See figure 1)

Classic double peak lactulose sibo breath test result
Figure 1: Classic double peak observed during a lactulose breath test. Two distinct rises in gas levels during the breath test are observed. Peak one occurs when bacteria in the small intestine ferment the lactulose. The second peak happens as the lactulose reaches the colon, where colonic bacteria begin their fermentation process.

Double Peak Results: Transition from Diagnostic Use

Historically, a double peak was considered a clear indicator of SIBO. The idea was that if lactulose caused gas levels to rise in both the small and large intestines, bacterial overgrowth was present in the small intestine. However, with advancements in understanding SIBO and improved breath testing techniques, the double peak is no longer used as a primary diagnostic criterion. Now, research shows that the timing and levels of gas production can be influenced by multiple factors including gut motility and variations in the transit time of lactulose through the intestines.

Despite this, a double peak is still a common finding in breath testing. It can offer useful clinical information, especially for differentiating between small intestinal fermentation (indicative of SIBO) and colonic fermentation.

The Transition Period: 100-120 Minutes

One crucial aspect of lactulose breath testing is the transition period between 100 and 120 minutes. During this time, lactulose moves from the small intestine into the large intestine. This may result in a temporary drop in measurable gas activity often seen on breath test results. Levels drop because lactulose has finished fermenting in the small intestine but hasn’t yet begun in the colon.

This transition phase can be helpful for clinicians in interpreting results. For example, if a significant gas rise occurs before 120 minutes, it suggests bacteria in the small intestine are producing those gases. This rise is diagnostic for SIBO. However, if gas levels stay low or drop during the transition, then rise sharply after 120 minutes, it indicates fermentation in the large intestine. Fermentation in the large intestine is normal and expected. However, extreme increases may suggest irregularities.  Delayed transition periods can occur especially in patients with slow gut motility, constipation and gastroparesis (see Figure 2). 

Example of delayed double peak in SIBO breath test results
Figure 2: Double peak observed during a lactulose breath test. Baseline elevated hydrogen gas activity and transition period at 140 minutes suggest slow gut motility.

Importance of Differentiating Small vs. Large Intestinal Activity

Although the double peak is no longer a diagnostic requirement for SIBO, it remains valuable for assessing bacterial activity throughout the digestive tract. By analyzing both the early (small intestine) and late (large intestine) fermentation patterns, clinicians determine if bacterial overgrowth is confined to the small intestine or if other digestive issues, such as colonic dysbiosis, might also be present. The transition period between 100 and 120 minutes offers further insight. It helps pinpoint where gas production is happening—information that can guide diagnostic and treatment decisions.

Double Peak Case Study

Presentation: A 42 year old male with sudden onset of severe constipation, bloating, flatus and lower diffuse abdominal pain since food poisoning in the summer of 2023. 

After the first positive SIBO breath test, he was treated with a combination of herbal and prescriptive antibiotics and an herbal prokinetic. The patient reported initial symptom improvement and then progressively worsening constipation and bloating.                         

Retesting indicated lower gas activity from the previous breath test. However, an “elevated” baseline and late double peak indicate reduced gut motility and delayed intestinal emptying. Prescriptive prokinetic was begun with frequent monitoring (every 2-4 weeks) until motility improved without bloating. The goal is to eventually titrate off motility support over time. 

Prolonged double peak case study
Case Study Image 1: First breath test was a strong positive. Baseline levels are elevated.  Delayed emptying into the colon is indicated.
Double peak results indicating delayed colonic emptying
Case Study Image 2: Second breath test was negative. Baseline levels are elevated. Results indicate delayed emptying into the colon.

Conclusion

The double peak pattern in lactulose breath testing provides important clues about how bacterial fermentation occurs in both the small and large intestines. While no longer considered diagnostic for SIBO on its own, observing the timing and levels of gas production in relation to the transition period differentiates between small intestinal overgrowth and normal colonic fermentation. For patients with unexplained digestive symptoms, understanding these patterns guides effective treatment strategies, ensuring a more tailored approach to gut health management. Learn more about abnormal breath test patterns.

Common Breath Test Results Part 3: Atypical Breath Test Results

Posted on by Bradley Bush

Atypical breath test patterns provide unique insights into digestive health and treatment direction. Consequently, interpret results within the clinical context. In general, despite expert and research-based guidelines for diagnostic breath testing, the interpretation of results lacks a clear, universally accepted consensus. This leaves room for broad, sometimes varied clinical interpretation, making results more functional and insightful. As hydrogen and methane breath test markers signal different underlying conditions based on timing, peak patterns, and gas fluctuations, clinicians rely on experience and understanding of individual patient patterns.

Atypical Breath Testing Patterns

Breath tests are essential for diagnosing digestive issues such as small/large intestinal bacterial overgrowth (SIBO and LIBO). However, some results fall into atypical patterns, giving unique insights. Here’s an overview of six atypical breath test result patterns.

Flat Methane

In this case of atypical breath results, methane (CH₄) levels are elevated, but flat, throughout the small intestine (0–120 min) (Figure 1). Elevated methane gas levels throughout test results suggest increased bacterial activity throughout the intestines or elevated colonic activity combined with reduced gut motility.

Test results showing an atypical breath test pattern: elevated flat methane
Figure 1: This is a lactulose breath test example of an atypical breath test result for a flat-line, elevated methane SIBO positive results.

Baseline Elevated Hydrogen

Initially high hydrogen (H₂) that either dips or remains high across the small intestine reflects potential pre-existing fermentation (Figures 2a, 2b). 

Atypical breath test results showing elevated baseline hydrogen
Figure 2a: This is an example of an elevated baseline hydrogen breath test. Elevated baseline (34 ppm) gas activity quickly cleared out with a significant reduction in activity. Possible causes of elevated hydrogen baselines include, but are not limited to, not following preparation diet guidelines, reduced gut motility, oral microbial imbalance, or significant colon gas activity.

 

Atypical breath test pattern showing baseline elevated hydrogen
Figure 2b: This is an example of an elevated baseline hydrogen breath test. An elevated baseline (34 ppm), followed by continued elevation in hydrogen gas activity does not meet diagnostic criteria for SIBO. Possible causes of continually elevated hydrogen gas activity include, but are not limited to, reduced gut motility, sugar malabsorption syndrome, and/or yeast overgrowth.

Flat Negative

Low hydrogen and methane (<3ppm) suggest low fermentative activity or microbial population (Figure 3).

atypical pattern for breath test showing flat methane and hydrogen levels in a negative SIBO result
Figure 3: This lactulose breath test result shows little to no measurable gas activity (hydrogen and methane). Common causes for a “flat-line” result include: testing too soon after antimicrobials (antibiotics, anti-fungals, herbal antimicrobials) or the presence of dominant hydrogen sulfide (H2S) SIBO.

Delayed Gut Motility

A hydrogen spike after 120 min with a second increase (double peak) shows slowed motility (Figure 4). Normally, a classic looking “double peak” of gas activity shows an initial spike in gas activity just prior to and after the intestinal transition zone (commonly around 100-120 min). The pattern becomes atypical when the double peak occurs outside of that time frame.

results showing delayed gut motility which is an atypical breath test pattern
Figure 4: These results show delayed emptying of lactulose from the small to large intestines. Reduced gut motility and delayed emptying may be identified with a transition zone occurring in the 140-160 minutes specimens.

Multiple Peaks and Valleys

Fluctuating H₂/CH₄ peaks may result from uneven microbial distribution (Figure 5).  Causes include segmental delays in motility, uneven transit times with pockets of microbes at different points, and SIBO. Additionally, different bacterial species producing gas at varying rates can fluctuate gas levels. Finally, physiological gut responses with normal motility patterns or minor motility disorders may influence gas patterns in the intestines.

multiple peaks and valleys in hydrogen methane breath tests are atypical
Figure 5: Multiple peaks and valleys in gas activity may be due to a variety of conditions.

Atypical Colon

A notable hydrogen and/or methane spike in the colon indicates possible microbial imbalance in the large intestines (Figures 6a, 6b).

Atypical colon breath test result
Figure 6a: This is atypical breath test example shows a slightly elevated SIBO (combined H₂ & CH₄) result with significant colon gas activity at 140-180 minutes. Additionally, the total hydrogen activity (Total Bacterial Load) of these results strongly suggests irregular colon fermentation/ microbial activity.

 

Atypical colon total bacterial load breath test results
Figure 6b: These breath test results show the total hydrogen gas activity (Total Bacterial Load) for the results in Figure 6a. Note high colon activity at 140-180 min.

Conclusion

Each atypical breath test pattern reveals distinct physiological and microbial dynamics. By combining the results with the clinical presentation, healthcare providers can create highly targeted and personalized treatment plans for various GI concerns. In some cases, these trends can be difficult to interpret. Neurovanna offers healthcare providers using our breath tests free consults with our SIBO expert Dr. Bradley Bush. Become a Neurovanna healthcare provider for quality and exclusive test results as well as skilled clinical support.

This is part 3 of a three part series on common breath test trends. Read part 1 to learn about common trends for lactulose and glucose SIBO breath tests. Part 2 discusses common trends in fructose, sucrose, and lactose sugar malabsorption breath test results.

Common Breath Test Results Part 2: Sugar Malabsorption Testing for Lactose, Fructose, and Sucrose 

Posted on by Bradley Bush

Sugar malabsorption affects many individuals, causing symptoms like bloating, gas, diarrhea, and abdominal discomfort. When the body cannot properly absorb sugars such as lactose, fructose, or sucrose, they pass into the large intestine. Once in the large intestine, gut bacteria fermented the sugars producing hydrogen and/or methane gas. Measuring the levels of hydrogen and methane gas through breath tests provides important insights into how well the body is digesting these sugars.

How Sugar Malabsorption Breath Tests Work

During a sugar malabsorption breath test, the patient consumes a specific sugar (either lactose, fructose, or sucrose). If the sugar is not properly absorbed in the small intestine, it reaches the colon. In the colon, bacteria ferment it producing hydrogen (H₂) and methane (CH₄) gas. Then, hydrogen gas absorbs into the bloodstream which carries it to the lungs. When the patient exhales into the collection tube, the gas is collected and measured using gas chromatography.

By analyzing the rise in hydrogen gas levels during the breath test, clinicians determine whether malabsorption is occurring and to what extent. The greater the rise in hydrogen, the more significant the sugar malabsorption.

Diagnostic Criteria for Sugar Malabsorption

The following diagnostic thresholds are used to interpret malabsorption breath tests for lactose, fructose, and sucrose:

  1. Hydrogen: A rise > 20 ppm above baseline during the breath test is diagnostic of malabsorption.
  2. Combined Hydrogen and Methane: A rise > 15 ppm above baseline during the breath test is diagnostic of malabsorption 
  3. Methane: A rise > 12 ppm above baseline during the breath test is diagnostic of malabsorption.

Common Trends for Each Sugar Malabsorption Test

Lactose Malabsorption (see Figure 1)

  • Hydrogen Gas Trend: For individuals with lactose intolerance, a significant rise in hydrogen levels commonly occurs within 60 to 90 minutes after ingesting lactose.
  • Diagnostic Interpretation:
    • A rise of 20 ppm or more indicates severe lactose malabsorption where the the small intestine absorbs little to no lactose.
    • An increase of 15 ppm or more indicates moderate malabsorption suggesting partial lactase deficiency.
    • A rise of 12 ppm or more indicates mild malabsorption. In this case, some lactose is absorbed, but not enough to prevent symptoms like gas and bloating.
  • Symptoms: Common symptoms include bloating, diarrhea, and abdominal pain after consuming dairy products.
Sugar malabsorption breath test results showing a negative results for lactose malabsorption
Figure 1: Example of lactose malabsorption breath test report. This breath test did not meet diagnostic criteria for malabsorption.

Fructose Sugar Malabsorption (see Figure 2)

  • Hydrogen Gas Trend: In cases of fructose malabsorption, hydrogen levels typically rise 30 to 60 minutes after consuming fructose.
  • Diagnostic Interpretation:
    • A rise of 20 ppm or more indicates severe fructose malabsorption, often causing significant digestive distress.
    • An increase of 15 ppm or more indicates moderate malabsorption, with symptoms occurring after consuming high amounts of fructose.
    • A rise of 12 ppm or more indicates mild malabsorption, where smaller quantities of fructose may still cause discomfort.
  • Symptoms: Fructose malabsorption can lead to bloating, gas, diarrhea, and cramping after consuming fructose-rich foods like apples, honey, or high-fructose corn syrup.
Test result showing positive fructose sugar malabsoprtion based on a breath test
Figure 2: Example of fructose malabsorption breath test report. Baseline measurement showed very little gas activity and then a significant increase was seen at 120 minutes. This breath test met diagnostic criteria for both an increase in hydrogen and combined (hydrogen + methane) gases.

Sucrose Malabsorption (see Figure 3)

  • Hydrogen Gas Trend: For those with sucrose malabsorption, hydrogen levels typically  rise 30 to 60 minutes after ingesting sucrose.
  • Diagnostic Interpretation:
    • A rise of 20 ppm or more suggests severe sucrose malabsorption, indicating a deficiency in the enzyme sucrase.
    • An increase of 15 ppm or more indicates moderate malabsorption, with symptoms occurring after consuming moderate amounts of sucrose.
    • A rise of 12 ppm or more indicates mild malabsorption, where some sucrose is absorbed, but not enough to prevent symptoms like bloating and gas.
  • Symptoms: People with sucrose malabsorption often experience digestive discomfort after consuming sugary foods like candy, baked goods, and sweetened beverages.
Breath test report showing positive for sucrose sugar malabsoprtion
Figure 3: Example of sucrose malabsorption breath test report. Even with an elevated baseline, this patient met diagnostic criteria for both an increase in hydrogen and combined (hydrogen + methane) gases.

What Do These Trends Mean?

The trends in hydrogen gas production during sugar malabsorption breath tests provide valuable insight into how well the body is absorbing specific sugars. A sharp increase in hydrogen levels, especially within the first 90 minutes, indicates a significant amount of undigested sugar is reaching the colon, where it is fermented by bacteria. The higher the hydrogen gas levels, the more severe the sugar malabsorption.

Understanding these hydrogen gas trends helps clinicians tailor dietary recommendations and treatment plans for individuals struggling with lactose, fructose, or sucrose malabsorption. For patients experiencing significant rises in hydrogen gas levels, reducing or eliminating the offending sugar from the diet can help manage symptoms and improve digestive health.

Prevent False Positives: Rule Out SIBO Before Sugar Malabsorption Breath Testing

SIBO can interfere with the accuracy of sugar malabsorption test results. Therefore, the North American Consensus for Breath Testing recommends ruling out Small Intestinal Bacterial Overgrowth (SIBO) with a glucose or lactulose breath test before testing for sugar malabsorption (such as lactose, fructose, or sucrose). If SIBO is present, bacteria in the small intestine may ferment sugars prematurely causing false positives during sugar malabsorption testing. By addressing SIBO first, clinicians can ensure that any malabsorption detected is due to enzyme deficiencies or transport issues rather than bacterial overgrowth.

This is part 2 of a three part series on common breath test trends. Read part 1 to learn about common trends for lactulose and glucose SIBO breath tests.

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.

The Case for Large Intestine Bacterial Overgrowth (LIBO)

Posted on by Bradley Bush

Breath testing is commonly used to diagnose Small Intestinal Bacterial Overgrowth (SIBO), but it could also be used to identify Large Intestine Bacterial Overgrowth (LIBO). The SIBO breath test measures amounts of the gasses hydrogen and methane produced by bacteria in the small intestine when they ferment carbohydrates. However, these breath tests also assess the hydrogen and methane gas activity in the large intestines. In most cases, this data is ignored, but this oversight may prevent proper diagnosis and treatment.

SIBO vs LIBO

In a healthy digestive system, the small intestine has relatively few bacteria compared to the large intestine. However, in SIBO, an overgrowth of bacteria in the small intestine ferments carbohydrates prematurely. This fermentation produces gasses, primarily hydrogen, methane, or hydrogen sulfide, which are absorbed into the bloodstream and then exhaled through the lungs. After a patient ingests a specific carbohydrate substrate, like lactulose or glucose, the breath test detects the levels of these gasses. Abnormally high levels indicate bacterial overgrowth in the small intestine.

The large intestine, or colon, is naturally populated with a vast number of bacteria responsible for fermenting undigested carbohydrates. This fermentation produces gasses like hydrogen, methane, and carbon dioxide as a normal part of digestion. Because this process is a normal function of the large intestine, the conventional medical community believes that assessing gas activity of the colon has no diagnostic value. In other words, elevated gas levels detected later in the breath test are expected, to some degree, and therefore do not specifically indicate pathology.

Large Intestinal Bacterial Overgrowth (LIBO) is a condition where there is an abnormal increase in the number and/or types of bacteria in the large intestine (colon). While the colon normally contains a vast and diverse population of bacteria that play essential roles in digestion, immunity, and overall health, an imbalance or overgrowth of certain bacterial species can lead to digestive issues and other health problems.

Key Aspects of Large Intestinal Bacterial Overgrowth (LIBO)

Causes of LIBO

  • Dietary Factors: A diet high in refined carbohydrates or sugars and low in fiber can promote bacterial overgrowth in the large intestine.
  • Dysbiosis: An imbalance in the gut microbiota, often caused by factors like antibiotics, poor diet, chronic stress, or other medications, can lead to LIBO.
  • Slow Transit Time: Conditions that slow down the movement of food through the colon, such as constipation, can lead to bacterial overgrowth as bacteria have more time to ferment undigested food.
  • Immune System Dysfunction: A weakened immune system, which fails to keep bacterial populations in check, can contribute to LIBO.

Symptoms of LIBO

  • Abdominal Bloating and Gas: Excess fermentation of undigested carbohydrates by bacteria can produce large amounts of gas, leading to bloating and discomfort.
  • Diarrhea or Constipation: LIBO can cause changes in bowel habits, leading to either diarrhea (due to rapid fermentation and irritation) or constipation (due to slower transit and hard stools).
  • Abdominal Pain: The buildup of gas and changes in motility can cause cramping and discomfort in the abdomen.
  • Fatigue and Malaise: Chronic LIBO can lead to malabsorption of nutrients, resulting in fatigue, nutrient deficiencies, and general feelings of unwellness.

Hydrogen Gas Production in the Large Intestine

The large intestine is home to a vast and diverse community of bacteria, many of which play a key role in digesting food components that were not fully broken down in the small intestine. These bacteria ferment undigested carbohydrates, fibers, and other nutrients, producing gasses as byproducts. Hydrogen gas (H₂) is one of the primary gasses produced during this fermentation process.

When carbohydrates, especially complex carbohydrates and fibers, reach the large intestine, they become substrates for bacterial fermentation. The bacteria break down these carbohydrates to obtain energy, and in the process, hydrogen gas is released along with other gasses like carbon dioxide (CO₂) and methane (CH₄).

Fate of Hydrogen Gas in the Large Intestine

  • Hydrogen-Consuming Microbes: In a healthy gut, hydrogen gas produced by one group of bacteria is often consumed by other microbes. For example:
      • Methanogenic Archaea: These microbes convert hydrogen gas into methane, which is another gas commonly found in the colon.
      • Sulfate-Reducing Bacteria: These bacteria use hydrogen to reduce sulfate to hydrogen sulfide (H₂S).
      • Acetogens: These microbes can convert hydrogen gas into acetate, which is a short-chain fatty acid beneficial for gut health.
  • Exhalation and Flatulence: Some of the hydrogen gas is absorbed into the bloodstream and then exhaled through the lungs, which is why hydrogen breath tests are used to diagnose certain gastrointestinal conditions. The remaining hydrogen gas, along with other gasses produced in the colon, can be expelled as flatulence.

Conditions Influencing Hydrogen Production in the Large Intestine

  • Dietary Composition: Diets high in fermentable fibers, sugars, and complex carbohydrates can increase hydrogen gas production in the large intestine because they provide more material for bacterial fermentation.
  • Gut Microbiome Balance: The balance of different types of bacteria in the large intestine influences hydrogen production. A healthy balance means that hydrogen production and consumption are balanced, minimizing excess gas.
  • Digestive Disorders: Conditions like irritable bowel syndrome (IBS), small intestinal bacterial overgrowth (SIBO), or malabsorption syndromes can lead to increased hydrogen production, contributing to symptoms like bloating, discomfort, and gas.

Summary

Hydrogen gas is indeed produced in the large intestine as a result of bacterial fermentation of undigested carbohydrates and fibers. The gas is either consumed by other gut microbes, absorbed into the bloodstream and exhaled, or expelled as flatulence. The production of hydrogen gas in the colon is a normal part of digestion, but excessive production may contribute to digestive discomfort, bloating, excessive flatus, irritable bowel symptoms and may suggest the presence of LIBO. Total hydrogen activity assessed during breath tests, e.g. the Neurovanna Total SIBO Bacterial Load, offer another functional diagnostic tool for assessing the presence and extent of LIBO. 

Start testing with Neurovanna or contact us for more information.

Learn more about the author, Dr. Bradley Bush.

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.

A Review of Breath Testing

Posted on by Bradley Bush

Small Intestinal Bacterial Overgrowth (SIBO) is a condition characterized by an excessive growth of bacteria in the small intestine. Diagnosing SIBO accurately is crucial for effective treatment, and one of the primary diagnostic tools is breath testing. Breath tests typically use either lactulose or glucose as substrates.

Breath Testing for SIBO Breath testing measures the amount of hydrogen and methane gasses produced by bacteria in the small intestine. These gasses are not produced in significant quantities by human cells but are byproducts of bacterial metabolism. The presence and levels of these gasses in the breath can indicate bacterial overgrowth.

Types of Breath Tests

  1. Lactulose Breath Test (LBT)
  2. Glucose Breath Test (GBT)

Lactulose Breath Test (LBT) Lactulose is a non-absorbable sugar that passes through the small intestine into the colon. When lactulose is fermented by bacteria in the small intestine, it produces hydrogen and methane, which are absorbed into the bloodstream and exhaled in the breath.

Procedure

  1. Preparation: Patients fast for at least 12 hours before the test.
  2. Baseline Breath Sample: A baseline breath sample is collected to measure hydrogen and methane levels.
  3. Ingestion: The patient drinks a lactulose solution.
  4. Sampling: Breath samples are collected at regular intervals (usually every 15-20 minutes) for about 2-3 hours.

Interpretation There are a variety of published diagnostic criteria for lactulose breath tests. These are the most clinically relevant SIBO diagnostic criteria:

  • A rise over lowest preceding value in hydrogen production of 20 parts per million (ppm) or greater within 120 minutes after ingesting lactulose
  • A rise over lowest preceding value in methane production of 10 ppm or greater within 120 minutes after ingesting lactulose
  • A rise over lowest preceding value in the combined sum of hydrogen and methane production of 15 ppm or greater within 120 minutes after ingesting lactulose.

Advantage

  • Can detect overgrowth throughout the entire small intestine.

Disadvantage

  • Potential for false positives due to rapid transit time or colonic fermentation are possible, but most experienced practitioners can reduce false positives by combining clinical presentation with the tests results.

Glucose Breath Test (GBT) Glucose is a sugar that is absorbed in the proximal small intestine (the first part of the small intestine). If bacteria are present in this region, they will ferment glucose, producing hydrogen and methane.

Procedure

  1. Preparation: Similar to the lactulose breath test, patients fast before the test.
  2. Baseline Breath Sample: A baseline breath sample is collected.
  3. Ingestion: The patient drinks a glucose solution.
  4. Sampling: Breath samples are collected at regular intervals for up to 2-3 hours.

Interpretation There are a variety of published diagnostic criteria for glucose breath tests. Below are the most clinically relevant SIBO diagnostic criteria:

  • A rise over lowest preceding value in hydrogen production of 12 parts per million (ppm) or greater within 120 minutes after ingesting glucose.
  • A rise over lowest preceding value in methane production of 10 ppm or greater within 120 minutes after ingesting glucose.
  • A rise over lowest preceding value in the combined sum of hydrogen and methane production of 12 ppm or greater within 120 minutes after ingesting glucose.

Advantages

  • Higher published specificity and lower false positive rate compared to lactulose, although this is less of an issue with an experienced practitioner.
  • Less likely to be influenced by colonic bacteria since glucose is usually absorbed before reaching the colon.

Disadvantages

  • May miss bacterial overgrowth in the distal (farther) parts of the small intestine.
  • Does not provide additional information on colonic bacterial activity.

Comparison of Lactulose and Glucose Breath Tests

Lactulose Breath Test

  • Pros: Can assess the entire small intestine
  • Cons: Higher rate of false positives due to colonic fermentation; influenced by intestinal transit time

Glucose Breath Test

  • Pros: Higher specificity; less influenced by colonic bacteria
  • Cons: May not detect overgrowth in the distal small intestine

Clinical Considerations Test Selection

  • The choice between lactulose and glucose breath tests depends on clinical judgment and specific patient circumstances.
  • Some practitioners may prefer one test over the other based on their familiarity and the patient’s symptoms.

Results Interpretation

  • Both tests require careful interpretation by experienced clinicians to avoid misdiagnosis.
  • False positives and negatives can occur, so results should be considered alongside clinical symptoms and other diagnostic information.

Summary

Breath testing with lactulose and glucose provides a non-invasive and relatively simple method for diagnosing SIBO. Each test has its advantages and limitations, and the choice of test should be tailored to the patient’s needs and clinical presentation. Accurate interpretation of these tests is crucial for effective diagnosis and management of SIBO.   for the diagnosis of SIBO are available and have their own pros and cons.

For further detailed information, consult sources such as:

  • Pimentel, M., et al. “Hydrogen and Methane-Based Breath Testing in Gastrointestinal Disorders: The North American Consensus.” The American Journal of Gastroenterology.
  • Lauritano, E. C., et al. “Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome.” Gut.

What is SIBO?

Posted on by Bradley Bush

Small Intestinal Bacterial Overgrowth (SIBO) is a condition where an excessive number of bacteria grow in the small intestine. While the large intestine is home to a rich bacterial population, the small intestine typically contains far fewer bacteria. When these bacteria overgrow in the small intestine, they interfere with digestion and nutrient absorption, leading to a variety of symptoms and health complications.

Common Symptoms of SIBO

  • Abdominal Bloating and Distention: Excess gas production by the bacteria leads to bloating and a sensation of fullness
  • Diarrhea: Bacterial overgrowth can disturb normal digestion, leading to frequent, loose stools
  • Constipation: Certain types of SIBO slow down intestinal motility, resulting in constipation
  • Abdominal Pain and Discomfort: Gas buildup and inflammation cause cramping and discomfort
  • Flatulence: Increased gas production by the bacteria leads to excessive passing of gas
  • Nausea: Disrupted digestion and bacterial byproducts can cause nausea
  • Fatigue: Nutrient malabsorption depletes energy, contributing to fatigue
  • Weight Loss: Persistent malabsorption and reduced appetite can lead to unintentional weight loss

Less Commonly Discussed Symptoms of SIBO

  • Gastroesophageal Reflux Disease (GERD) and Hiatal Hernias: SIBO can exacerbate GERD and sliding hiatal hernias due to increased intra-abdominal pressure from gas, impaired gut motility, and chronic inflammation.
  • Electrolyte Imbalance: SIBO can lead to diarrhea and malabsorption, causing imbalances in electrolytes like sodium and potassium.
  • Adrenal Fatigue: Chronic gastrointestinal distress from SIBO can strain the adrenal glands, leading to adrenal fatigue, which may affect hormone levels such as cortisol, DHEA, and aldosterone.
  • Nonalcoholic Fatty Liver Disease (NAFLD): SIBO can contribute to the development of NAFLD through chronic inflammation, increased intestinal permeability, and metabolic dysfunction.

Complications Caused by SIBO

  • Nutritional Malabsorption: Bacterial overgrowth disrupts nutrient absorption, leading to deficiencies.
  • Vitamin Deficiencies: Particularly of fat-soluble vitamins (A, D, E, K) and vitamin B12
  • Mineral Deficiencies: Poor absorption can lead to deficiencies in iron and calcium
  • Intestinal Permeability (Leaky Gut): Bacterial toxins and inflammation damage the gut lining, allowing larger molecules to pass through.
  • Chronic Inflammation: Persistent bacterial overgrowth triggers ongoing inflammation in the gut.
  • Blood-Brain Barrier Permeability: Lipopolysaccharides (LPS) from bacteria can increase permeability of the blood-brain barrier, allowing inflammatory molecules to reach the brain and affect the hypothalamus.
  • Neuroinflammation: Inflammation in the brain can disrupt hormone regulation, including cortisol production, by affecting the hypothalamus and pituitary gland.

Nutritional Malabsorption and Clinical Side Effects

  • Vitamin B12 Deficiency: Can cause anemia, fatigue, weakness, and neurological symptoms like tingling or numbness
  • Fat-Soluble Vitamin Deficiencies (A, D, E, K): 
    • Vitamin A: Leads to poor vision in low light and immune dysfunction
    • Vitamin D: Results in bone pain, muscle weakness, and a higher risk of fractures
    • Vitamin E: Can cause neurological issues and impaired immune response
    • Vitamin K: May lead to an increased tendency for bleeding and easy bruising
  • Iron Deficiency: Causes anemia, leading to fatigue, weakness, and pale skin
  • Calcium Deficiency: Results in weakened bones, increased fracture risk, and potentially osteopenia or osteoporosis
  • Protein Malabsorption: Can cause muscle wasting, edema, and overall weakness

 

Condition

SIBO Prevalence Rate

Health Study Controls

0-20%

Celiac disease

up to 67%

Crohn’s disease

up to 88%

Ulcerative Colitis

81%

Chronic Fatigue Syndrome

81%

Fibromyalgia

93%

Irritable Bowel Syndrome

up to 78%

Gastrectomy

63-78%

Connect Tissue Disease (e.g. Scleroderma)

43-55%

Diabetes Type II

up to 44%

Hypothyroidism

54%

Obesity

up to 41%

Rosacea

46%

Hypochlorhydria (drug-induced)

up to 78%

Summary

SIBO is characterized by excessive bacterial growth in the small intestine, leading to digestive discomfort, nutrient malabsorption, and a wide range of symptoms. The bacteria produce gasses and toxins that not only cause gastrointestinal issues but also contribute to more serious complications such as vitamin and mineral deficiencies, inflammation, and even neurological disturbances. Addressing SIBO is critical to restoring digestive health and preventing these long-term effects.