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You may be one of many patients suffering with bloating, abdominal pain, constipation, or diarrhoea and your GP has diagnosed you with irritable bowel syndrome (IBS) and your symptoms have not responded to treatment. Alternative you have given no diagnosis at all for your suffering.

My experience is that many of those perplexing symptoms are related to small intestinal bacterial overgrowth (SIBO).

What is Small Intestinal Bacterial Overgrowth? (SIBO)

Small intestine bacterial overgrowth (SIBO) is a condition in which abnormally large numbers of commensal bacteria (or other microorganisms) are present in the small intestine.

The gastrointestinal (GI) tract normally contains many species of bacteria and other micro-organisms (collectively known as the gut microbiome), with the largest numbers of bacteria found in the colon (end part of the large intestine) and lower amounts in the small intestine.

What are the symptoms of SIBO?

Some people with SIBO may not have any symptoms at all whilst, others will experience symptoms similar to irritable bowel syndrome. SIBO is involved in over half the cases of IBS and as high as 84% in one study using breath testing as the diagnostic marker.

Eradication of this overgrowth leads to a 75% reduction in IBS symptoms. Either bacterial overgrowth or the overgrowth of methanogenic archaea leads to impairment of digestion and absorption and produces excess quantities of hydrogen, hydrogen sulphide, or methane gas.

The most common symptoms of SIBO are:



Tummy pain





Reflux – heart burn

Malabsorption of food and nutrients – especially fats

Weight gain, weight loss

Other symptoms maybe include:

Rash (rosacea)


Body pain




Brain Fog

Tingling and numbness in arms and legs


B12 deficiency

How SIBO Causes the Symptoms of IBS

There are two main pathophysiological issues involved in SIBO.

First, bacteria can ferment carbohydrates and consume other nutrients ingested by the host simply by their inappropriate location in the small intestine. This allows them premature exposure to host nutrition before there is time for absorption.

Bacterial fermentation produces hydrogen and/or hydrogen sulphide gas. In addition, M. smithii produces methane. M. smithii may be present in the intestinal tracts of up to 95.7% of humans. Microbial gas leads to the IBS symptoms of bloating, pain, altered bowel movements.

How is SIBO being treated?

The most accepted treatment regimens for SIBO include antibiotics – specifically Rifaximin (Xifaxin). However, SIBO is extremely stubborn & difficult to treat. In fact, Rifaximin is only 40-80% effective in eradicating SIBO in patients with IBS-D, and it often recurs in patients within several months of treatment.

The Functional Medicine Approach to SIBO

When most people have not recovered from SIBO it is because their bacterial imbalance was only partially addressed by their treatment.

I use a multi facet functional medicine approach to treat my patients with SIBO.

The first step is to adequately assess the function of organs and systems that are integral to your ability to maintain a healthy microbiome.

Conducting functional tests (such as digestive tests/vitamin deficiencies/metabolic imbalances etc.) helps us uncover the possible root cause of your symptoms and enable me to create targeted, more personalized recommendations.

If you suffer from SIBO or IBS get in touch to find out how I can help you to return to normal.