Small Intestinal Bacterial Overgrowth (SIBO)

Definition

Small Intestinal Bacterial Overgrowth: excessive proliferation of bacteria (normally present in small numbers) in the small intestine, causing malabsorption and digestive symptoms.

How it works

SIBO results from abnormal bacterial proliferation in the small intestine, where few bacteria normally reside. This may be due to reduced intestinal motility, pancreatic insufficiency, incompetent ileocecal valve, or dysbiosis. Bacteria ferment dietary sugars, producing gas (hydrogen, methane, carbon dioxide) responsible for bloating, flatulence, diarrhea, or constipation. SIBO is diagnosed with a breath test and treated with targeted antibiotics followed by microbiome restoration with an adapted diet.

Role

Causes malabsorption, excessive fermentation, and debilitating digestive symptoms.

Examples

• Hydrogen-producing SIBO
• Methane-producing SIBO
• Mixed SIBO
• Associated with irritable bowel syndrome

Recommendations

Follow a low FODMAP diet during and after SIBO antibiotic treatment. Gradually reintroduce more complex foods and restore your microbiome with adapted probiotics and prebiotics.

Key takeaway

SIBO is treatable but requires a combined antibiotic-diet-microbiome restoration approach.

Related terms