SIBO is a condition where bacteria normally maintained at low levels in the small intestine overgrow and colonise where they should not. The small intestine is primarily a nutrient-absorption zone not a fermentation chamber. Bacterial overgrowth there causes immediate post-meal bloating, abdominal pain, chronic diarrhea or constipation, nutrient deficiencies, and fatigue. SIBO is estimated to affect up to 78% of IBS patients and is frequently misdiagnosed as IBS alone.
