Small Intestinal Bacterial Overgrowth

Small Intestinal Bacterial Overgrowth (SIBO) – Abnormal number of bacteria present in the small intestine.

These are normal bacteria that are usually found in the large intestine (colon), and are pathobionts, not pathogens. These bacteria ferment starches and fibres into gases which damage the small intestine and cause symptoms such as:



Alternating constipation and diarrhoea


Abdominal cramping

Bloating and/or wind

Burping and Acid Reflux/GORD


Food sensitivities

Joint pain

Skin rashes

Fatigue, anaemia – Iron and B12 deficiency

Respiratory symptoms such as asthma

SIBO can occur when there is damage to the migrating motor complex (MMC) and enteric nervous system. Thus, preventing bacteria from being cleared/swept out of the small intestine. Impaired flow through the intestine via ileocecal valve dysfunction and adhesions may result in SIBO. As well as impaired digestion due to microbiome dysfunction, chronic stress, secretory IgA, pancreatic and/or brush border enzyme deficiency, poor bile flow and low stomach acid. Certain medications and health conditions can also cause SIBO.

SIBO causes damage to the absorptive surface of the small intestine, subsequently, impairing the absorption of nutrients from food. In addition to causing gut permeability, which allows larger particles to pass through the damaged gut lining, resulting in an immune/inflammatory response.

The breath test is a simple, non-invasive test. After a 24-hour preparatory diet, the lactulose, glucose or fructose test substrate is swallowed. Breath samples are collected every 20 minutes for 3 hours.