Small intestinal bacterial overgrowth (SIBO) is a condition characterised by excessive growth of bacteria in the small intestine.

Accurate diagnosis of small intestinal bacterial overgrowth (SIBO) plays a crucial role in effectively managing and treating SIBO.

Diagnostic testing, particularly the SIBO breath test, holds significant value in detecting and evaluating this condition.

We will discuss what SIBO is in more detail, how it is diagnosed, and the importance of the SIBO test.

What is Small Intestinal Bacterial Overgrowth?

SIBO occurs when there is an abnormal overgrowth of bacteria in the small intestine. These bacteria release either hydrogen or methane gases or both. You can predominantly present with having one gas or both. The causes of SIBO can vary, including factors such as impaired gut motility, low stomach acid, or anatomical abnormalities.

Certain medical conditions like irritable bowel syndrome (IBS), Crohn's disease, or a history of abdominal surgery may also contribute to its development.

Common symptoms of SIBO include abdominal pain, bloating, diarrhoea, constipation, nausea, uncomfortable feeling of fullness and flatulence.

Diarrhoea is associated with hydrogen dominant SIBO, whereas constipation is associated with methane dominant SIBO.

Diagnostic SIBO Test

Accurate diagnostic testing is essential to confirm the presence of SIBO and distinguish it from other gastrointestinal disorders. As well as identifying the type of SIBO - hydrogen or methane dominant SIBO.

One primary tool for SIBO diagnosis is the SIBO breath test.

This non-invasive test measures the gases produced by bacteria in the small intestine, providing valuable insights into the condition.

The SIBO Breath Test: The Process

The SIBO breath test involves collecting breath samples to analyse the gases produced in the small intestine. During the test, baseline breath samples are collected, followed by the ingestion of a sugar solution. The subsequent breath samples are collected at specific intervals to measure the levels of these gases.

The lactulose breath test uses the sugar substrate lactulose to measure how the hydrogen and methane gases respond. Lactulose is poorly absorbed by the intestine and if SIBO is present, the bacteria will begin to breakdown the lactulose before it reaches the large intestine, causing an early increase in gas production. The remaining lactulose will then reach the large intestine, causing a second increase in gas production. This test is ideally used alongside a glucose breath test to reduce the likelihood of a false-negative result.

In a glucose breath test the sugar substrate used is glucose. As it is absorbed in the first section of the small intestine it will therefore not cause a rise in gas, as it typically doesn’t reach the large intestine where bacteria breakdown carbohydrates. Due to its rapid absorption, glucose may not reach the distal section of the small intestine; therefore the glucose test is best used alongside lactulose to assess the entire small intestine. 

This is the gold standard for SIBO testing. 

Interpreting Test Results and Treatment Options

Interpreting SIBO test results is crucial for effective management.

A positive result indicates the presence of SIBO and identifies whether it is predominantly hydrogen or methane gas present, guiding your healthcare provider in tailoring treatment plans. 

Treatment and management options for SIBO include antibiotic treatment or herbal antimicrobials to reduce bacterial overgrowth, dietary changes to limit the intake of fermentable carbohydrates, or the use of an elemental diet to starve the bacteria in the small intestine.

A multidisciplinary approach, considering individual patient factors and medical history, is essential for successful SIBO management.

Other Conditions Usually Accompanying SIBO

SIBO can be associated with other conditions and factors. Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is commonly found in individuals with SIBO.

Additionally, digestive disorders such as irritable bowel syndrome (IBS) and conditions affecting stomach acid levels or delayed stomach emptying may coexist with SIBO. Previous episodes of food poisoning or gastrointestinal infections can also increase the risk of developing SIBO.

Recognising and addressing these accompanying conditions is crucial as they can contribute to the severity of symptoms and may require specific treatment approaches tailored to each individual's unique needs.

To treat SIBO, a comprehensive approach is often needed, considering these associated factors.

The Limitations of SIBO Diagnostic Testing

While diagnostic testing is valuable, there are certain limitations of any SIBO test to consider.

First, a SIBO breath test may produce false negatives or positives, especially if the bacterial overgrowth is localised or intermittent. Although this is not a common problem, as with most medical tests, there is some room for doubt. If you do not trust the result of your test, seek further testing.

Additionally, factors like dietary changes or the presence of fungal overgrowth can complicate the interpretation of SIBO test results. If SIBO is strongly suspected despite negative test results, another breath test and evaluation may be necessary.

Another limitation of SIBO testing is the SIBO breath test cost. 

FAQs About SIBO Testing and Breath Test Results

Now that you know what SIBO is and how it is tested, let's answer some frequently asked questions about SIBO testing and treatments.

How do nutritionists test for SIBO?

Nutritionists test for SIBO using a breath test kit which is completed by the patient at home/ These tests measure the levels of hydrogen and methane gases in the breath, providing valuable information to detect and evaluate small intestinal bacterial overgrowth (SIBO).

What are the first signs of SIBO?

The first signs of SIBO may include digestive symptoms such as bloating, nausea, acid reflux, abdominal pain, and diarrhoea or constipation. Other potential indicators include lactose intolerance, digestive symptoms such as delayed stomach emptying, and specific SIBO symptoms.

Recognising these early signs can prompt individuals to seek the support of a nutritionist and potentially receive a timely diagnosis and treatment. If you are diagnosed with irritable bowel syndrome and do not believe this is the root of the issue, seek further testing.

Will the NHS test for SIBO?

Currently, the National Health Service (NHS) in the UK does not routinely offer specific tests for small intestine bacterial overgrowth (SIBO). However, if SIBO is suspected, healthcare providers may refer you for specific testing, such as lactulose breath tests, to assess gastrointestinal function.

Can I test myself for SIBO?

You can get at-home breath test kits for SIBO, however make sure you source this from a credible lab. We recommend you get the advice of a nutrition professional before spending money on SIBO testing. 

Summing Up: Understanding SIBO: The Significance of Diagnostic Testing

Thorough diagnostic testing is vital for understanding and effectively managing SIBO.

If you are experiencing symptoms such as abdominal pain, bloating, constipation or diarrhoea, it is essential to seek medical evaluation and discuss the possibility of SIBO testing with your healthcare provider. By taking action and getting tested, you can gain valuable insights into your condition and receive the appropriate treatment.

Remember, SIBO is a complex condition that requires a multidisciplinary approach. Collaborating with healthcare providers who specialise in gastrointestinal disorders will ensure that you receive the best care possible. With the right diagnosis and personalised treatment plan, you can regain control over your digestive health and improve your overall well-being.

Don't let the symptoms of SIBO hold you back. Take the first step towards understanding and managing your condition by reaching out to us to arrange adequate care and reliable testing.