Small Intestinal Bacterial Overgrowth (SIBO) leads to the production of various metabolic waste products by the overgrown bacteria. These waste products can cause a range of symptoms and side effects. The list below shares the main metabolic waste products produced by SIBO bacteria and the associated side effects.

1. Hydrogen Gas

Produced by fermentation of carbohydrates by anaerobic bacteria.

Side Effects

• Bloating: Excess hydrogen gas causes abdominal distension and discomfort.
• Diarrhea: Hydrogen gas can increase gut motility, leading to loose stools.

2. Methane Gas

Produced by: Archaea, particularly Methanobrevibacter smithii, which consumes hydrogen.

Side Effects:

• Constipation: Methane gas slows intestinal transit time, leading to constipation.
• Bloating and Discomfort: Methane gas can also cause abdominal bloating and pain.

3. Hydrogen Sulfide Gas

Produced by: Sulfate-reducing bacteria such as Desulfovibrio.

Side Effects:

• Diarrhea: Hydrogen sulfide can irritate the gut lining, leading to diarrhea.
• Rotten Egg Smell: The gas has a characteristic foul odor, leading to malodorous flatulence.

4. Lactic Acid

Produced by: Fermentation of carbohydrates by lactic acid bacteria such as Lactobacillus.

Side Effects:

• Acidosis: Accumulation of lactic acid can contribute to an acidic environment in the gut, potentially causing pain and discomfort.
• Bloating and Gas: Excess lactic acid can lead to increased gas production and bloating.

5. Ammonia

Produced by: Breakdown of proteins and amino acids by bacteria

Side Effects:

• Neurotoxicity: High levels of ammonia can cross into the bloodstream and affect the brain, leading to symptoms like confusion and fatigue.
• Gut Irritation: Ammonia can damage the gut lining, contributing to inflammation and discomfort.

6. Short-Chain Fatty Acids (SCFAs)

Produced by: Fermentation of dietary fibers by gut bacteria.

Side Effects:

• Bloating and Gas: Excess SCFAs can lead to gas production, causing bloating and discomfort.
• Diarrhea: Some SCFAs can increase intestinal motility, leading to diarrhea.

7. Ethanol

Produced by: Fermentation of sugars by yeasts and some bacteria.

Side Effects:

• Intoxication: In severe cases, excess ethanol production can lead to symptoms similar to alcohol intoxication.
• Liver Stress: Chronic production of ethanol can stress the liver, potentially exacerbating liver-related conditions.

8. Succinate

Produced by: Fermentation processes of certain bacteria.

Side Effects:

• Metabolic Acidosis: Excess succinate can contribute to metabolic acidosis, leading to systemic symptoms like fatigue and muscle weakness.

9: Lipopolysaccharides (LPS)

LPS are large molecules found in the outer membrane of Gram-negative bacteria. They are released when these bacteria die and their cell walls break down. LPS are potent endotoxins and can trigger significant immune responses in the human body

Managing the Impacts of SIBO

In addition to the effects of metabolic waste, SIBO bacteria have clinical impacts beyond gas and bloating. They can exacerbate or even cause some autoimmune and inflammatory conditions.

Managing SIBO typically involves dietary modifications, probiotics, and in some cases, antibiotics or herbal antimicrobials to reduce bacterial overgrowth and alleviate these symptoms.

If you are a patient looking for a Neurovanna provider, contact us. Healthcare providers set up a Neurovanna account for access to gold-standard Quintron breath testing and SIBO experts.

 

References:

– Pimentel, M., et al. (2003). “Small Intestinal Bacterial Overgrowth: Associations With Irritable Bowel Syndrome and Gastrointestinal Motility Disorders.” Gastroenterology.

– Rezaie, A., et al. (2017). “Hydrogen and Methane-Based Breath Testing in Gastrointestinal Disorders: The North American Consensus.” The American Journal of Gastroenterology. https://pmc.ncbi.nlm.nih.gov/articles/PMC5418558/

– Lauritano, E. C., et al. (2008). “Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome.” Gut.

– Tana, C., et al. (2010). “Altered Profiles of Intestinal Microbiota and Organic Acids May Be the Origin of Symptoms in Irritable Bowel Syndrome.” Neurogastroenterology & Motility. https://pubmed.ncbi.nlm.nih.gov/19903265/

Small Intestinal Bacterial Overgrowth (SIBO) occurs when bacteria from the large intestine colonize the small intestine. The top 10 bacteria commonly associated with SIBO are responsible for many of the clinical side effects of SIBO. The list below shares the most common side effects for each of those 10 SIBO bacteria when overgrown, along with additional clinically relevant details regarding histamine production, autoimmune associations, and other health impacts:

Escherichia coli (E. coli)

• Side Effects: Bloating, abdominal pain, diarrhea, and gas. E. coli overgrowth can also increase the risk of leaky gut syndrome by causing inflammation in the gut lining, leading to a compromised intestinal barrier.
• Clinical Relevance: E. coli is known to release lipopolysaccharides (LPS), which can trigger systemic inflammation. LPS can contribute to autoimmune reactions and has been linked to conditions such as autoimmune thyroiditis (Hashimoto’s disease).

Streptococcus

• Side Effects: Diarrhea, gas, bloating, and abdominal discomfort. Streptococcus can lead to significant inflammation due to the release of bacterial toxins, contributing to digestive disturbances.
• Clinical Relevance: Streptococcus species have been implicated in promoting histamine production, which can exacerbate symptoms of histamine intolerance. Excessive histamine may worsen symptoms in people with Mast Cell Activation Syndrome (MCAS) and food sensitivities.

Lactobacillus

• Side Effects: Gas, bloating, diarrhea, and abdominal discomfort. While typically beneficial in the large intestine, Lactobacillus overgrowth in the small intestine can lead to excessive fermentation.
• Clinical Relevance: Certain strains of Lactobacillus can also produce D-lactate, which can lead to lactic acidosis and neurological symptoms, such as confusion and fatigue. This overgrowth may also contribute to histamine production in some cases, aggravating conditions like MCAS.

Bacteroides

• Side Effects: Abdominal pain, bloating, and diarrhea. Overgrowth of Bacteroides can disrupt the balance of the gut microbiota and contribute to chronic inflammation.
• Clinical Relevance: Bacteroides species are associated with increased production of thyroid antibodies, which can exacerbate autoimmune conditions like Hashimoto’s thyroiditis. They can also influence systemic inflammation and are linked to the development of non-alcoholic fatty liver disease (NAFLD).

Enterococcus

• Side Effects: Bloating, gas, diarrhea, and abdominal pain. Enterococcus overgrowth is associated with chronic gut inflammation and may interfere with normal gut motility.
• Clinical Relevance: Enterococcus is linked to the production of biofilms, which can protect bacterial colonies from both the immune system and antibiotics, making infections harder to treat. It has also been associated with urinary tract infections and is increasingly found to be resistant to antibiotics, including vancomycin-resistant Enterococcus (VRE).

Klebsiella

• Side Effects: Severe bloating, gas, and abdominal pain. Klebsiella species can produce significant amounts of gas and promote inflammation in the gut.
• Clinical Relevance: Klebsiella is strongly associated with autoimmune conditions, particularly ankylosing spondylitis and other spondyloarthropathies. It can trigger molecular mimicry, where the immune system attacks the body’s tissues, mistaking them for bacterial invaders.

Clostridium

• Side Effects: Diarrhea, abdominal cramping, and bloating. Certain species, such as Clostridium difficile, can cause severe inflammation in the gut and colitis.
• Clinical Relevance: Clostridium species, particularly C. difficile, can produce harmful toxins that lead to colitis and severe gut inflammation. Overgrowth of this bacteria is often linked to antibiotic use and can be difficult to treat. Some Clostridium species are associated with increased histamine production, exacerbating symptoms in histamine-sensitive individuals.

Proteus

• Side Effects: Bloating, gas, and diarrhea. Proteus overgrowth contributes to significant digestive disturbances and systemic toxin production.
• Clinical Relevance: Proteus is another biofilm-producing bacteria that can evade immune system attacks. It has been linked to urinary tract infections and can also contribute to kidney stones due to its ability to produce urease, which breaks down urea into ammonia, increasing alkalinity in the urine.

Methanobrevibacter smithii

• Side Effects: Constipation and bloating. This archaea produces methane, which slows intestinal transit time and contributes to constipation.
• Clinical Relevance: Methane production by Methanobrevibacter smithii is linked to constipation-predominant IBS (IBS-C). High methane levels can also correlate with slower motility, leading to a higher risk of SIBO recurrence. Some studies suggest it may also affect thyroid function by slowing gut motility and altering hormone metabolism.

Prevotella

• Side Effects: Bloating, diarrhea, and gas. Overgrowth of Prevotella can disrupt gut balance, leading to inflammation and digestive symptoms.
• Clinical Relevance: Prevotella is commonly linked to chronic inflammatory conditions such as rheumatoid arthritis and periodontitis. It may exacerbate autoimmune responses by triggering systemic inflammation. Prevotella overgrowth has also been observed in individuals with dysbiosis associated with Western diets high in refined carbohydrates.

 

Summary of Common Side Effects and Clinical Relevance:

• Bloating: Most of these bacteria produce excessive gas through fermentation, leading to bloating and abdominal discomfort.
• Diarrhea: Disruption of digestion can cause frequent, loose stools, often seen with bacteria like E. coli, Streptococcus, and Bacteroides.
• Constipation: Methanobrevibacter smithii is linked to methane production, which slows motility, causing constipation.
• Histamine Production: Bacteria like Streptococcus, Lactobacillus, and Clostridium can contribute to elevated histamine levels, which aggravate conditions like MCAS.
• Autoimmune Associations: Bacteria such as Klebsiella, Bacteroides, and Proteus have strong links to autoimmune conditions, including ankylosing spondylitis, Hashimoto’s thyroiditis, and rheumatoid arthritis.
• Systemic Inflammation: The overgrowth of these bacteria, through mechanisms like LPS release (E. coli) and biofilm production (Enterococcus), can trigger systemic inflammation, leading to conditions such as leaky gut, autoimmune flare-ups, and metabolic disorders.

Managing SIBO with Clinical Insight

Effectively managing SIBO requires not only addressing bacterial overgrowth but also understanding the broader clinical implications each bacterial strain has on the body. Whether through histamine management, addressing autoimmune triggers, or treating systemic inflammation, treating SIBO patients in a holistic manner requires an appreciation and understanding of bacteria’s impact on health.

Our SIBO experts are available to assist Neurovanna healthcare providers with understanding SIBO. Complete our new account form to become a Neurovanna healthcare provider. If you are a patient seeking SIBO care, contact us to find a Neurovanna practitioner near you.