Small intestinal bacterial overgrowth (SIBO)

Bacterial overgrowth syndrome

SIBO is defined as presence of excessive bacteria in the small intestine.
Usually mainly lactobacilli and enterococci colonize the small bowel. In case of small intestinal bacterial overgrowth bacteria from the large intestine such as bifidobacteria or even pathogens overgrow the physiological flora of the small intestine.

Possible causes are:

  • Damage of the smalll intestine flora, for example through antibiotics or toxins
  • immunodeficiency
  • defect of the ileocaecal valve, which separates the small and the large intestine
  • pancreatic and liver diseases
  • lack of stomach acid
  • diverticula or small bowel stenosis, for example in case of Crohn's disease.

As part of small intestine bacterial overgrowth it often comes to increased sugar fermentation, therefore the H2 breath test is suitable for diagnosis. Already in fastening condition the hydrogen content is increased.

The bacterial overgroth syndrome can trigger flatulence, diarrhea and pain and cause deficiency symptoms.

For intestinal rehabilitation only preparations with lactobacilli and enterococci should be used, but no bacteria of the large intestine such as bifidobacteria or E. coli.

Related diagnostics


intelligent microbiome diagnostics with resilience index, functional groups and FODMAP type