Small Intestinal Bacterial Overgrowth

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Other names for Small Intestinal Bacterial Overgrowth

Small bowel bacterial overgrowth
Intestinal dysbiosis
Excess bacteria in the small intestine

Synopsis of Small Intestinal Bacterial Overgrowth

Small Intestinal Bacterial Overgrowth (SIBO) is a condition in which an abnormal number or type of bacteria colonize the small intestine, leading to fermentation, inflammation, and digestive dysfunction. Normally, the small intestine contains relatively low bacterial levels compared to the colon. In SIBO, these bacteria can interfere with nutrient absorption and cause bloating, gas, abdominal pain, diarrhea, or constipation. It is often linked to structural or functional gastrointestinal problems and may be chronic or recurring if the underlying cause is not addressed. SIBO can significantly impair quality of life and is frequently underdiagnosed.

Types:

  • Hydrogen-dominant SIBO: Leads to diarrhea; common with excess carbohydrate fermentation

  • Methane-dominant SIBO (IMO): Often causes constipation; linked to archaea rather than bacteria

  • Hydrogen sulfide SIBO: Associated with foul-smelling gas and diarrhea; harder to detect

  • Mixed SIBO: Involves more than one gas type and symptom profile

Common Causes:

  • Impaired motility (e.g., due to diabetes, hypothyroidism, scleroderma)

  • Structural abnormalities (adhesions, diverticula, post-surgery changes)

  • Chronic use of PPIs (proton pump inhibitors) or opioids

  • IBS (especially IBS with bloating)

  • Food poisoning or gastrointestinal infections

  • Low stomach acid or bile production

Severity Causes:

  • Untreated or recurrent infections

  • Damage to the migrating motor complex (MMC)

  • Autoimmune dysfunction or intestinal permeability

  • Nutrient malabsorption (especially B12, fat-soluble vitamins)

  • Coexisting conditions like celiac disease or Crohn’s

When to See a Doctor:

  • Persistent bloating, gas, or abdominal pain after meals

  • Chronic diarrhea or constipation without other explanation

  • Fatigue or weight loss with digestive symptoms

  • History of GI surgery or long-term reflux medication use

  • Symptoms of malabsorption (greasy stools, nutritional deficiencies)

Natural remedies for Small Intestinal Bacterial Overgrowth

Low-FODMAP diet: Reduces fermentable carbohydrates that feed bacterial overgrowth. May quickly reduce gas, bloating, and pain in SIBO patients.

Probiotics (specific strains): Can help rebalance gut flora and inhibit SIBO-promoting microbes. Lactobacillus and Bifidobacterium strains may support post-treatment maintenance.

Berberine (if part of herbal blends): Natural antimicrobial effective against pathogenic bacteria in the gut. Often used as an alternative to antibiotics.

Activated charcoal: Helps absorb bacterial toxins and reduce gas and bloating. Should be used short-term and away from other medications or supplements.

Magnesium: Relieves constipation and supports motility. Especially helpful in methane-dominant SIBO to encourage regular elimination.

Digestive bitters (from herbal blends): Stimulate stomach acid and bile flow, improving digestion and limiting bacterial overgrowth.

Vitamin B12: May be necessary in supplement form if malabsorption has occurred. Bacteria in SIBO can consume B12, leading to deficiency symptoms.

Stress management: Reduces impact on the gut-brain axis and supports healthy motility. Practices like breathwork, yoga, and meditation are helpful.