Is SIBO the cause of your Irritable bowel?


Small intestinal bacterial overgrowth is otherwise known as SIBO and may be an underlying factor in many people suffering from irritable bowel symptoms. This condition is characterised by an overgrowth of bacteria in the small intestine which can interfere with the healthy structure and function of the small intestine.
The large colon has many bacteria inhabiting it but the small intestine has relatively few bacteria in comparison. An overgrowth of bacteria in the small intestine means that bacteria can break down certain foods faster than they should resulting in excess bloating and abdominal discomfort.

The small intestine is responsible for the absorption of food and nutrients and also helps in part to regulate our immune system. It is no surprise then that an overgrowth of bacteria in the small intestine can cause malabsorption of nutrients such as B12 among others as well as deficiencies in the essential fat-soluble vitamins such as E, D, A and K.

An overgrowth in bacteria can damage the absorptive villi structures that line the small intestine which not only reduces the absorption of foods but also sets the stage for food allergies and intolerance’s. Long term issues may result in a ‘leaky gut’ whereby the intestinal barrier becomes permeable which then allows undigested food molecules to pass through the gut barrier into the blood stream causing further immune dysfunction and possibly autoimmune issues.

Most patients with SIBO have been told that they have IBS from their doctor. Probiotics or prebiotics will not provide relief for these patients.

The five most common symptoms patients with SIBO complain about are-
1/ Bloating and abdominal discomfort
2/ Diarrhoea (usually hydrogen-based SIBO)
3/ Constipation (methane-based SIBO)
4/ Reflux, gas and burping
5/ In more severe cases there may be fatigue, weight loss and symptoms related to vitamin deficiencies.


Firstly, SIBO is a secondary condition which means it doesn’t occur naturally without certain factors being present.
One of the main issues causing SIBO is a dysfunctional migrating motor complex.
A healthy small intestine has a MMC (Migrating motor complex) which stimulates a peristaltic ‘wave’ every 1.5 hours in order to cleanse the small intestine from bacteria and food. Many people have issues with motility for a number of reasons and this peristaltic motion doesn’t happen as regularly which means bacteria can build up to unhealthy levels in the small intestine.

Bad food poisoning or severe gastro-enteritis can damage the MMC.

Many people have gallbladder issues which can also lead to an increase of bacteria in the small intestine. Bile naturally helps with motility and is in itself, a good anti-bacterial which can keep bacteria levels in check.

Low stomach acid is a another issue that SIBO sufferers often have. A good amount of acid is released from the stomach when we eat and this also kills off bacteria and parasites in our food before they reach the small intestine. Acid released from the stomach also kicks off a healthy digestive cascade which results in bile and pancreatic enzymes being released further down in the small intestine. These secretions are all essential for the proper breakdown and absorption of nutrients.

Certain bowel surgeries or repeated antibiotic courses are also risk factors for the development of SIBO .

There are multiple risk factors for SIBO but the above are the most common we see in clinical practice.


Treating SIBO effectively means reducing the amount of bacteria living in the small intestine with the administration of specific anti-bacterials in conjunction with a specific diet. For long-term resolvement of SIBO, the practitioner needs to identify and correct the primary issues that were the catalyst for SIBO to occur in the first place. After SIBO has been treated, it is important for the patient to be monitored and educated to prevent relapse as it is likely that relapse will occur again if the patient is treated with anti-bacterials alone without addressing root causative factors.