Condition: Small Intestinal Bacterial Overgrowth (SIBO)

Small intestinal bacterial overgrowth (SIBO) occurs when the bacteria that normally live within the large intestine start to grow into the small intestine. This increase in the bacterial population in the small intestine results in problems with the digestive system such as poor absorption of nutrients.

SIBO is most common in people who have pre-existing gut-related health issues such as inflammatory bowel disease or coeliac disease and less common in patients with bowel symptoms but healthy bowels such as food intolerances or irritable bowel syndrome (IBS) but can affect anyone.

Normally, the bacteria in the small intestine are controlled by chemicals like gastric acid, bile, enzymes and immunoglobulins and also the normal movement of food contents to the large intestine. SIBO occurs when the normal chemical functions and the movement of the gut are altered allowing bacteria to overgrow from the large bowel into the small bowel

A number of factors can cause this to happen including:

• Complications of abdominal surgery
• Structural problems in and around the small intestine
• Certain medical conditions, including Crohn's disease, radiation enteritis, scleroderma, coeliac disease and diabetes
• Overuse of certain medications
• A weakened immune system

Many SIBO symptoms are the same as those of other gastrointestinal conditions. Depending on the severity of the condition symptoms can include:

• Abdominal pain
• Abdominal swelling
• Nausea
• Bloating
• Indigestion
• Flatulence
• Diarrhoea
• Constipation
• Loss of appetite
• An uncomfortable feeling of fullness after eating
• Unintentional weight loss
• Fatigue

Diagnosing SIBO based on the symptoms alone is difficult due to the overlap with other conditions. A simple breath test can measure the levels of hydrogen in the breath. A change in hydrogen levels after drinking a sugary drink can indicate  an overgrowth of bacteria.

If possible, the underlying cause of SIBO should be treated. The initial treatment for SIBO is a course of antibiotics to reduce the abnormal bacteria. In patients with underlying health conditions, the bacteria may return so long-term treatment may be needed.