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Diagnosing Small Instestinal Bacterial Overgrowth (SIBO) and Intestinal Methane Overgrowth (IMO) requires skill and expertise. Many clinicians, including dietitians, can find the management of these conditions difficult to figure out. Current breath tests are misdiagnosing people with IBS symptoms (such as bloating, gas, constipation and diarrhoea), being incorrectly interpreted as a FODMAP intolerance. While a low FODMAP diet may initially help ease symptoms, it is often a ‘band-aid’ solution, leaving the underlying cause of SIBO and IMO undiagnosed and ultimately the cause of symptoms untreated so they reoccur.

While hydrogen breath testing can be a useful clinical tool, interpreting the results can be difficult. Accredited Practising Dietitian Alison Stewart explains that the current healthcare model and testing pathways for SIBO can be inaccurate, using lactulose (which is 73% effective) and/or glucose solutions on hydrogen breath testing, rather than fructose (85% effective). Additionally, the timing of the rise in substrates used to test for malabsorption is not being accounted for in current recommended testing. Further to this, Alison explains how testing for hydrogen alone in breath tests, as opposed to also testing for methane and hydrogen sulphide (which are also produced by bacteria), can result in a misdiagnosis, resulting in unresolved symptoms.

In mananging a SIBO and IMO diagnosis, it is crucial that a holistic focus is maintained; the prescription of specific prebiotics (such as PHGG powder), certain strains of probiotics (where relevant), and natural treatment options (such as oregano oil for IMO, utilising iberogast as a prokinetic, or natural laxatives such as magnesium oxide), with antibiotics (such as rifaxamin for SIBO), can be useful. The treatment plan varies on a case-by-case basis and on the diagnosis, and may involve working in collaboration with general practitioners, gastroenterologists, or other experienced healthcare professionals in this sector to ensure that client symptoms are appropriately treated.

Summary:

• Current breath tests are misdiagnosing people with IBS symptoms (such as bloating, gas, constipation and diarrhoea), being incorrectly interpreted as a FODMAP intolerance.
• According to the North American Concensus Guidelines, a positive test for SIBO involves a rise of >20ppm of hydrogen before 90 minutes, a rise of 12ppm of methane before 90 minutes, or a combined rise of 15ppm before 90 minutes. A positive IMO test involves any test with >10ppm at any time.
• In interpreting breath tests, it is crucial that relevant tests are requested, including for methane and hydrogen sulphide, as hydrogen breath testing alone can result in misdiagnoses.
• A collaborative healthcare approach is key, and this may involve referring onto experienced practioners in this space (such as for antibiotic or natural therapeutic product prescriptions), or undertaking professional development.

Alison Stewart has been practising as a dietitian for 29 years. She has mostly worked in private practice, collaborating with GP’s, gastroenterologists, diabetes educators, aged care facilities, exercise physiologists and psychologists.

Alison found some of her clients diagnosed with FODMAP intolerances did not improve with conventional dietetic strategies. She has investigated the management of SIBO and begun incorporating treatments in her clients using a more functional medicine approach.

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