Small intestine bacterial overgrowth (SIBO) is a condition in which there is an abnormal overgrowth of bacteria in the small intestine. The small intestine is typically relatively free of bacteria, but in SIBO, bacteria that are normally found in the large intestine migrate into the small intestine, where they can ferment carbohydrates and cause symptoms.

Common symptoms of SIBO include abdominal pain, bloating, diarrhea, constipation, and malnutrition. SIBO can also lead to nutrient deficiencies, as the bacteria in the small intestine can interfere with the normal absorption of nutrients.

SIBO is often caused by a dysfunction in the mechanisms that normally control the growth of bacteria in the small intestine, such as the ileocecal valve, which separates the small and large intestines, or the migrating motor complex (MMC), which helps to clear bacteria from the small intestine.

Risk factors for SIBO include conditions that slow down gut motility, such as diabetes and hypothyroidism, and the use of certain medications, such as proton pump inhibitors (PPIs), which reduce stomach acid.

The diagnosis of SIBO involves a breath test, in which the individual is asked to ingest a sugar solution and then breathe into a bag at intervals. The presence of elevated levels of certain gases in the breath indicates the presence of SIBO.

Treatment for SIBO typically involves a combination of dietary changes, antibiotics, and probiotics. It is important to work with a healthcare provider to develop a comprehensive treatment plan, as SIBO can be a complex and persistent condition.