Key takeaways
  • SIBO often goes undiagnosed due to its overlapping symptoms with other conditions and the lack of awareness in traditional medical settings
  • Breath testing is the gold standard for diagnosing SIBO, measuring hydrogen and methane gases produced by bacteria in the small intestine
  • Managing SIBO requires a holistic approach involving dietary changes, lifestyle modifications, and potentially supplements or medications

During my three years as a lab technician, I analysed over 10,000 SIBO breath tests. I was surprised to learn just how prevalent SIBO is - and these are just the cases I knew about. I couldn't help but wonder how many people were walking around completely unaware they had a bacterial overgrowth in their small intestine. And importantly, had this condition been explored as a contributing factor in their health condition? 

So what are the symptoms to look for and how do you test for SIBO?

In this article I'll share why SIBO often goes undiagnosed or misdiagnosed in Western medical settings, the different types of SIBO testing methods, test interpretation - what you need to know, and the good news beyond your diagnosis - how you can manage your condition, holistically.

What is SIBO?

Small intestinal bacterial overgrowth (SIBO) is a condition where bacteria that normally live in the large intestine have relocated and overgrown in the small intestine. 

The top half of the small intestine (known as the proximal) typically contains relatively few bacteria due to the presence of stomach acid and the effects of peristalsis (the action of movement through the gastrointestinal tract). However, when these protective mechanisms against excessive bacterial growth fail, SIBO can manifest. These excess organisms result in multiple intestinal symptoms like:

The cause of SIBO can be singular or multifactorial. Some possible causes may include impaired motility (movement) through the gastrointestinal tract, impaired flow through the intestinal tract, or medications.

Even though SIBO was identified in 1939, research has developed exponentially in the last 25 years. SIBO can often go undiagnosed, misdiagnosed or not even considered as an association with a person’s ill health, as functional testing is not always discussed or offered by healthcare providers. 

How to test for SIBO

Stool tests are a valuable diagnostic tool for a wide range of digestive disorders, particularly those affecting the colon and lower gastrointestinal tract. However, it does not accurately reflect the bacterial population of the small intestine, where SIBO occurs. Therefore diagnosis of SIBO via stool analysis is not considered reliable or standard practice. 

Breath testing is the gold standard for SIBO diagnosis primarily due to its non-invasive nature, simplicity, cost-effectiveness, safety, and diagnostic effectiveness. These factors collectively make it a practical and reliable tool for practitioners to diagnose and manage SIBO.

The accuracy of diagnosis relies on the quality of the test, in particular the frequency at which the breath samples are taken, and the preparation guidelines. Therefore, sourcing a high-quality test through a healthcare professional is advised. 

Breath testing for SIBO should result in the identification of two gases being released by bacteria in the small intestine, either hydrogen or methane or both. Research has found it difficult to be precise with species of bacteria that are located in the small intestine, as this area of the gastrointestinal tract is difficult to access. Some of the most common bacteria identified in SIBO are Escerichia coli, Aeromonas, Klebsiella and Methanobrevibacter (which are actually archaea not bacteria). 

More relevant is understanding which gas/es are being produced, how much is being produced and where this is happening in the GIT. The best way to assess this is breath testing. That is, it can not be assessed by symptoms alone.

Testing and identifying the type of gases released by bacteria in the small intestine is crucial for several reasons:

  1. Diagnosis of SIBO: Different bacteria produce different gases. Hydrogen-producing bacteria and methane-producing archaea are typically involved in SIBO. A breath test that measures hydrogen and methane levels can help diagnose SIBO and indicate the presence and extent of bacterial overgrowth
  2. Understanding symptoms: The type of gas produced can correlate with specific symptoms. For example, methane production is often associated with constipation-predominant SIBO, while hydrogen production is more commonly linked to diarrhoea-predominant SIBO. Knowing the predominant gas can help tailor treatment to address specific symptoms more effectively
  3. Targeted treatment: Some people need no supplements, some need antimicrobials, some choose antibiotics, some need prebiotics, probiotics or herbal medicines to improve digestive enzyme functions or increase stomach acid to help reduce symptoms. Some people just need dietary modification
  4. Treatment monitoring: By measuring gas levels before and after treatment, practitioners can assess the effectiveness of the treatment. A decrease in the levels of hydrogen or methane indicates that the bacterial overgrowth is being successfully reduced
  5. Preventing recurrence: Identifying underlying conditions that might be causing SIBO, such as motility disorders or structural abnormalities in the intestines is important to prevent recurrence.

Which SIBO test kit should you do

There are three testing kits: lactulose, glucose or fructose - which can help determine the foods that you might be reacting to. Each of these sugars will help pinpoint foods that might be contributing to SIBO symptoms.

The lactulose test may identify bacterial overgrowth throughout the small and large intestines. If opting for a single substrate, lactulose is the best option.

Similar to the lactulose test, the glucose breath test involves drinking a glucose solution. Glucose is a simple sugar that is normally absorbed quickly in the small intestine. 

The fructose breath test may be useful if you have obvious symptoms when consuming fruit or other fructose-containing foods. 

How to prepare for a SIBO test

SIBO breath testing is a convenient test that can be done at home. 

To prepare for a SIBO breath test, your practitioner will provide you with clear preparation guidelines.

Procedures, medications and supplements

The guidelines will include information about any procedures, medications and supplements you will need to avoid or stop in the lead-up to your SIBO test.

  • One month before testing - avoid antibiotics, colonoscopy, colonic or barium investigation
  • One week before testing - avoid probiotic supplements, probiotic foods (yoghurt, Yakult, fermented foods), herbal antimicrobials
  • One day prior to testing, stop - laxatives, digestive aids (enzymes or hydrochloric acid), non-essential supplements

Preparation diet

A preparation diet must be followed the day prior to testing, with the aim of reducing fermentation in the small intestine. Preparation begins 24 hours prior to testing in 2 stages of 12 hours. If you’re chronically constipated, 2-3 days of prep diet is recommended. 

During the first 12 hours you'll follow a restricted meal plan. The last 12 hours will be fasting, and you’ll perform the test first thing in the morning. 

Performing the test

Testing involves collecting 10 breath samples every 20 minutes over  3 hours, using a breath collection device. 

Once breath sampling is completed, SIBO testing kits are forwarded back to the testing lab via express post.

Interpreting SIBO test results

SIBO breath testing is looking for evidence of two gases, either hydrogen or methane, being present in your breath samples.

Results are considered positive if there is a rise of either of these gases in the first 6 samples of testing. A rise of 20ppm equals a positive result for hydrogen. A rise of 12ppm equals a positive result for methane. However, it’s important to consult with your healthcare practitioner as the results of your SIBO breath test report will not always necessarily reflect your symptoms and health concerns.

Common pitfalls when interpreting SIBO test results

A common pitfall of test interpretation is not considering the incremental rise of these gases. Interpreting the severity and the location of the small intestinal bacterial overgrowth within the small intestine is extremely important. Working with a practitioner who is skilled in understanding your SIBO test result and able to interpret your results as mild, moderate or severe, not just positive or negative is fundamental in improving symptoms.

For example, a mild rise of hydrogen gas may suggest only small amounts of bacteria are present in the small intestine and therefore, only minor dietary modification and minimal or no supplementation may be recommended. Alternatively, a high rise in hydrogen throughout sampling may indicate large numbers of small intestine bacterial overgrowth and therefore require more extensive dietary modification, for longer periods. 

Dietary modification may include avoidance of foods such as gluten, dairy and sugar, but may also require minimising portions of foods consumed, especially those foods high in fibre. The main goal of dietary modification is to reduce and remove bacteria from the small intestine and begin to repair the small intestine environment, which untreated, can become inflamed, compromised in its ability to absorb nutrients and lead to a leaky gut. 

The type of dietary modification and length of time implementing these changes to your diet should be monitored and adjusted with the advice of your practitioner and according to changes or improvements in your symptoms.

SIBO case study

Susan was a 55-year-old woman who had been separated for 10 years, had raised four children and had recently been made redundant from her job. She was eating a diet based on processed foods, drinking alcohol every night, and had a lot of financial stressors and family pressures in her life.

Her symptoms included bloating, flatulence, brain fog, nausea, joint pain, extreme fatigue and constipation. 

SIBO breath testing was completed and confirmed the diagnosis of SIBO.

Susan’s treatment initially included strict dietary modification which was reviewed weekly, lifestyle behaviour changes such as avoiding alcohol, increasing physical activity and reducing stress with walks in nature, and supplementation with herbal antimicrobials, prebiotics and probiotics to help correct the microbial imbalance.

After only two weeks of treatment, Susan reported all her symptoms had reduced, and after four weeks she was feeling younger, more vital and healthier than she had in years. 

She was having daily bowel movements (which she’d never done before) and her friends and family were commenting on how well she was looking. 

This is not always the way things go though. For some, the journey through SIBO treatment and onwards can be slow and can take many months. The rate of relapse after treatment is high because many people do not address the original causes of their development of SIBO. Causes of SIBO should always be considered in preventing relapse. 

Beyond testing: a holistic approach to SIBO management

SIBO treatment tends to be varied due to several factors:

  • Diversity of symptoms: Different symptoms may require different treatment approaches
  • Underlying causes: SIBO can be caused by different underlying conditions (chronic stress, low stomach acid, repeated courses of antibiotics, poor diet, excessive alcohol consumption, a history of gastroenteritis lasting for longer than a few days, autoimmune disease, side effects of medications, traumatic brain injury, abdominal surgeries, etc.). Each underlying cause my necessitate a different treatment strategy
  • Microbial diversity: The types of bacteria that overgrow in SIBO can differ from person to person. Some people might have an overgrowth of methane-producing bacteria, while others have more hydrogen-producing bacteria, affecting which treatments are most effective
  • Recurrence rates: SIBO is known for high recurrence rates, which may require ongoing or repeated treatment. The choice of treatment might also evolve based on the effectiveness of previous interventions and the patient's tolerance to them

Natural treatment for SIBO may include:

  • Dietary modification for 6-12 weeks 
  • Supplementation in many circumstances, beyond 12 weeks, such as prebiotics and probiotics

Monitoring this process and modifying treatments according to a patient’s response is important in the functional medicine approach to treating SIBO.

If a patient feels 90% improvement in their symptoms by the time a treatment protocol has been completed, re-testing for SIBO is not always necessary. However, if symptoms are still experienced or have changed at this time, it is worth retesting to confirm the clearance of SIBO, or discuss the need for further investigation of ongoing causes of GIT dysfunction. 

People are often misinformed that this condition has a simple diagnosis and treatment - yet it is very nuanced. Managing and treating SIBO requires professional healthcare guidance due to the condition's often complex symptoms and test results. Symptoms like bloating, diarrhoea, and constipation can vary widely and overlap with other disorders, making accurate diagnosis challenging.

Breath test results need careful interpretation to avoid misdiagnosis and ensure targeted antibiotic therapy. Your healthcare practitioner can provide personalised SIBO natural treatment protocols while monitoring progress and adjusting treatments. Identifying and addressing underlying causes is crucial for preventing recurrence, highlighting the importance of a comprehensive, individualised approach to SIBO management.

So if you suspect SIBO, don’t guess - get tested. Our gut health experts can help you pinpoint if you have SIBO, or another digestive disorder, and provide support to get your gut health back on track. 

Curious to know more? Read our comprehensive overview of the functional medicine approach to SIBO.

lorraine cussen functional medicine practitioner pale blue coloured top standing smiling
Lorraine Cussen
For more than two decades, Lorraine has been supporting patients with a range of health concerns including digestive conditions (e.g. gastritis, SIBO, IBS, Crohn's disease, Ulcerative Colitis), women’s health concerns and fertility, cardiometabolic conditions (e.g. Cardiovascular disease, Diabetes), thyroid conditions, and overall well-being.
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{ "datePublished": "Jul 12, 2024" }