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Ah! My Gut. Is it SIBO? (Small Intestinal Bacterial Overgrowth)

Introduction: Small Intestinal Bacterial Overgrowth (SIBO) is a condition characterized by an excessive growth of bacteria in the small intestine. This overgrowth can disrupt the normal digestive processes, leading to various uncomfortable symptoms and potential nutrient malabsorption. In this blog post, we will delve into the definition of SIBO, its development, common risk factors/causes, and provide four effective recommendations that may be considered when treating this condition.

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What is Small Intestinal Bacterial Overgrowth (SIBO)?

SIBO occurs when the balance of bacteria in the small intestine is disrupted, resulting in an abnormal increase in bacterial populations. Normally, the small intestine has relatively fewer bacteria compared to the large intestine. However, when bacteria from the large intestine migrate upward into the small intestine, or when the small intestine fails to clear bacteria effectively, SIBO can develop.

Types of SIBO:

  1. Hydrogen-Dominant SIBO (H-SIBO): H-SIBO is characterized by an overgrowth of bacteria that produce high levels of hydrogen gas as a byproduct of their metabolism. These bacteria, including Escherichia coli (E. coli) and Klebsiella pneumoniae, ferment carbohydrates in the small intestine, leading to excessive hydrogen gas production. H-SIBO is commonly associated with symptoms such as bloating, flatulence, abdominal pain, and diarrhea.

  2. Methane-Dominant SIBO (M-SIBO): M-SIBO occurs when there is an overgrowth of bacteria, primarily Methanobrevibacter smithii, that produce high levels of methane gas. Methane gas slows down gut motility, impairing the movement of food through the digestive system. This can lead to symptoms like constipation, bloating, and abdominal discomfort. M-SIBO is often associated with a delayed transit time in the small intestine.

  3. Hydrogen Sulfide SIBO (HS-SIBO): Hydrogen Sulfide SIBO is characterized by an overgrowth of bacteria that produce high levels of hydrogen sulfide gas as a metabolic byproduct. The primary bacteria involved in HS-SIBO are Desulfovibrio species. Hydrogen sulfide gas can cause various symptoms such as bloating, flatulence, abdominal pain, and diarrhea. However, it is important to note that HS-SIBO is a relatively newer area of research, and further investigation is needed to fully understand its clinical significance and optimal treatment approaches.

It's important to note that some individuals may have a combination of hydrogen-dominant and methane-dominant SIBO, referred to as mixed SIBO. In mixed SIBO, both hydrogen and methane gases are produced, and symptoms can vary depending on the balance of these gases.

Determining the specific type of SIBO requires diagnostic testing, such as a breath test, which measures the gases produced by bacteria in the small intestine after consuming a substrate like lactulose or glucose. Keep reading below for additional testing options.

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Causes and Risk Factors of SIBO:

  1. Impaired Gut Motility: Conditions such as intestinal adhesions, irritable bowel syndrome (IBS), or structural abnormalities in the digestive tract can slow down the movement of food through the small intestine, promoting bacterial overgrowth. An impaired ileocecal valve may contribute (the location where the small intestine, specifically the ileum, connects to the colon).

  2. Digestive Disorders: Underlying conditions such as celiac disease, Crohn's disease, and gastric surgery can disrupt the normal functioning of the small intestine, increasing the risk of SIBO.

  3. Low Stomach Acid: Insufficient production of stomach acid, often seen in conditions like chronic acid suppression or gastric surgery, can impair the sterilization of bacteria entering the small intestine, contributing to SIBO.

  4. Medications: The use of certain medications, such as proton pump inhibitors (PPIs), opioids, NSAIDs, or immunosuppressants, can disrupt the balance of gut bacteria and promote the development of SIBO.


Effective Recommendations for Treating SIBO:

  1. Antibiotic Therapy: Antibiotics specifically targeting bacterial overgrowth in the small intestine are often prescribed to treat SIBO. Rifaximin is a commonly used antibiotic with minimal absorption, allowing it to target the bacteria in the small intestine effectively. Consult with a healthcare professional for appropriate antibiotic treatment. Herbal remedies are also use to rebalance the gut. Check out our eBook for additional supplement recommendations. Atrantil, shown below, is one product that helps with hydrogen dominant SIBO and consequently archaebacteria that use hydrogen as a food source.

  2. Probiotics and Prokinetics: Probiotics containing strains like Bifidobacterium and Lactobacillus have shown promise in restoring gut microbial balance. Additionally, prokinetic agents, such as herbal supplements or medications, can improve gut motility and aid in clearing bacteria from the small intestine.

  3. Dietary Modifications: Following a specific diet, such as the low FODMAP (Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols) or Specific Carbohydrate Diet (SCD), may help alleviate symptoms and reduce bacterial overgrowth. These diets restrict certain carbohydrates that are fermentable by gut bacteria. Caution when adding FODMAP foods back as symptoms can worsen.

  4. Address Underlying Causes: Treating the underlying conditions contributing to SIBO, such as celiac disease or gastric motility disorders, is crucial for long-term management. Collaborate with a healthcare professional to identify and address any root causes.

  5. Comprehensive gut testing can help elucidate what is going on in your individual gut along with organic acid testing to look at the byproducts of microbial metabolism. If you are interested investigating, check out our functional medicine packages here. And schedule a free 20-minute consult here.


Small Intestinal Bacterial Overgrowth (SIBO) is a condition characterized by an abnormal increase in bacteria in the small intestine. It can cause digestive symptoms and nutrient malabsorption. By understanding the causes and risk factors associated with SIBO and implementing effective treatment approaches, such as antibiotic therapy, probiotics, dietary modifications, and addressing underlying conditions, individuals can find relief and restore a healthy balance in their gut.

Disclaimer: The information provided in this blog post is for informational purposes only and should not be considered as medical advice. Always consult with a qualified healthcare professional for personalized recommendations and treatment options for SIBO or any other health condition.

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