Author: Bradley Bush

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.

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.