Small intestinal bacterial overgrowth


Diagnosing small intestinal bacterial overgrowth (SIBO) can pose challenges due to symptom overlap with other digestive disorders. When symptoms and medical history suggest SIBO, multiple tests may be necessary to evaluate bacterial overgrowth, fat absorption problems, or other potential underlying causes of symptoms.

The commonly recommended tests include:

  • Blood and stool tests: To investigate potential causes and complications of SIBO, blood tests can check for vitamin and protein deficiencies and a stool test can help detect undigested fats or bile acids.
  • Imaging tests: Tests like X-rays, computed tomography (CT) scans, or Magnetic resonance imaging (MRI) may be used to identify structural intestinal abnormalities.
  • Breath testing: In this test, a glucose-water mixture is consumed. One will need to breathe on a special device to determine the hydrogen and/or methane levels in their breath, indicating the presence of gas-producing bacteria in their gut. Elevated levels suggest an overgrowth of bacteria.
  • Small intestine aspirate and fluid culture: During this test, a flexible tube called an endoscope is inserted through the mouth and down into the small intestine to collect a sample of fluid for bacterial growth analysis. This test is the most reliable way to diagnose bacterial overgrowth.


SIBO frequently arises as a complication of another health condition and can lead to its own set of complications. Treatment of SIBO involves healthcare providers targeting the overgrowth, managing associated complications, and addressing the root cause. In instances where a structural issue is identified, surgery may be recommended for correction.

Antibiotics are commonly prescribed to tackle bacterial overgrowth, followed by management of acute complications which may involve nutritional support and dietary changes to alleviate symptoms.

  • Antibiotic therapy: Antibiotics can greatly reduce abnormal bacteria, but they may return after treatment ends, requiring long-term therapy. Antibiotics are sometimes rotated to prevent bacterial resistance, but this can also cause issues like diarrhea due to wiping out both normal and abnormal bacteria.

Based on symptoms and medical history, even without conclusive tests, antibiotics is typically the primary treatment for bacterial overgrowth. Additional tests are often required if antibiotics fail to resolve the issue.

  • Nutritional support: Treatment may involve nutritional support and supplements to address deficiencies in vitamins and minerals. A short-term strict diet may be implemented to manage symptoms, followed by a modified long-term diet plan to restore nutrition, and regulate bacterial overgrowth.

Correcting nutritional deficiencies is vital in treating SIBO, especially in individuals experiencing severe weight loss, as the damage caused by malnutrition may not always be reversible.

    • Nutritional supplements: Intramuscular injections of vitamin B-12, along with oral vitamins, calcium, and iron supplements may be prescribed.
    • Lactose-free diet: Avoiding most lactose-containing products or using lactase supplements may be recommended. Some may tolerate yogurt due to bacteria breaking down lactose during culturing. Adopting a lactose-free diet is advised to manage digestive distress caused by damage to the small intestine, as lactose intolerance may develop.