Hydrogen breath testing offers a glimpse into the intricate world of gastrointestinal disorders in a non-invasive and relatively cheap way.
This blog will explore the significance of hydrogen breath testing, its mechanism, preparation, and what to expect after the test.
We will focus on small intestinal bacterial overgrowth (SIBO), which can be diagnosed through this testing method, and why hydrogen breath tests do not diagnose food intolerances.
What is hydrogen breath testing?
Hydrogen breath testing is a non-invasive diagnostic method that measures the hydrogen gas levels in a person’s breath.
Under normal circumstances, carbohydrates (such as lactose, fructose or glucose) are broken down and absorbed in the large intestine.
However, if the gut cannot properly digest and absorb the carbohydrate, it travels to the large intestine, where the gut bacteria ferment it, producing hydrogen gas as a byproduct.
This gas is absorbed into the bloodstream and eventually exhaled through the breath.
The concentration of hydrogen in the breath is measured at regular intervals over a specific period after the carbohydrate ingestion.
Why are hydrogen breath tests not used for food intolerances?
There are many reasons why hydrogen breath tests are no longer recommended for food intolerances (e.g. lactose intolerance and fructose intolerance).
Firstly, they are not accurate or reproducible if repeated (2). This means you may get different results if you re-do the test, so you may get false positives or negatives!
They also use large amounts of lactose or fructose – more than you would typically eat in your diet. This could lead to a false positive result and unnecessary dietary restrictions.
Additionally, a positive result has limited real-world application. For example, it will not tell us how much lactose a person can tolerate without getting symptoms.
We know from the research that some people with lactose intolerance can tolerate up to 200ml milk daily without getting any symptoms, so we want to avoid unnecessary restrictions.
The best method to determine whether you have lactose intolerance is by cutting it out of your diet, and if this helps symptoms, then reintroducing it slowly to identify your tolerance level.
You can read more about lactose intolerance and how to identify if you have it in our blog post: Lactose intolerance.
How can you get a hydrogen breath test?
A trained specialist will carry out a hydrogen breath test at your usual healthcare provider if required, or they can be organized in a private clinic.
However, if you opt to go privately, you should be prepared to pay for the test, subsequent gastroenterology appointments, and any treatments covered by private health insurance.
As mentioned, hydrogen breath tests are not routinely given for fructose or lactose intolerance. You should not pay for this test privately, as the same issues with accuracy apply.
You can read more about getting a diagnosis of SIBO in our blog post: Unlocking the secrets of SIBO testing – a comprehensive guide for accurate diagnosis.
How to prepare for a hydrogen breath test
Preparing for a hydrogen breath test is essential to ensure accurate and reliable results. Proper preparation helps minimize external factors that could influence the test outcome.
Here are the key steps and guidelines to follow when preparing for a hydrogen breath test:
1. Query whether you can continue your medications
If you are taking antimicrobial medications for a suspected small intestinal bacterial overgrowth (SIBO), consult your healthcare provider about whether to stop the medication before the test (3).
Prokinetic medications that enhance gastrointestinal motility may also need to be paused a few days before the test, as they can influence the results (3).
2. Avoid specific foods for one day before the test.
In the 24 hours before the hydrogen breath test, it is essential to avoid certain foods and beverages that may affect the test results (3). These typically include:
- Dairy products
- High-fiber foods (such as beans, lentils, and whole grains)
- Certain fruits (e.g., apples, pears, cherries) and fruit juices
- Foods and drinks containing artificial sweeteners
- Carbonated beverages
The recommendations also suggest you do not smoke the day before your hydrogen breath test.
3. Fast for 8-12 hours before hydrogen breath testing
Fasting for at least 8 to 12 hours before the test is generally recommended (3). You should only drink water during this fasting period to ensure accurate baseline measurements.
Try to schedule the test at a convenient time when you can comfortably fast and avoid restricted foods. Usually, the first thing in the morning is ideal.
Remember to follow specific instructions from your healthcare provider or testing facility for the best outcomes. Follow their guidelines to avoid false results.
What is the process of a hydrogen breath test?
Your healthcare professional will explain the hydrogen breath testing procedure when you arrive. You can address any last-minute questions or concerns at this time.
Before the test begins, you will provide a baseline breath sample. This sample serves as a reference point for comparison with subsequent breath samples.
After collecting the baseline sample, you will be given a specific substrate to ingest, depending on the suspected condition.
Following substrate ingestion, breath samples will be collected regularly, typically every 15 to 30 minutes. Depending on the specific test protocol, this process may continue for several hours.
Each breath sample will be analyzed to measure the levels of hydrogen gas. Elevated hydrogen indicates substrate malabsorption, potentially pointing to an underlying gastrointestinal disorder.
Hydrogen breath testing is safe and well-tolerated for most individuals, but you may experience symptoms from consuming that substrate if intolerant, e.g., discomfort, bloating, or flatulence.
What happens after a hydrogen breath test?
After the test, you can go home or work as usual and resume your regular diet.
The healthcare provider will analyze the collected breath samples and interpret the results to make a diagnosis.
The steps and actions following the test depend on the results and the individual’s specific condition. However, you can expect a treatment plan which includes the following:
- Dietary and lifestyle recommendations
- Medications (e.g. antibiotics for SIBO)
- Plan for follow-up or monitoring of symptoms
Hydrogen breath testing offers a non-invasive diagnostic tool for small intestinal bacterial overgrowth (SIBO), which your gastroenterologist may arrange.
Although it used to be used for lactose or fructose intolerances, it is no longer recommended as it is inaccurate and may lead to needless food restrictions.
Adhering to the preparation guidelines optimizes the accuracy of the test. You will be able to go back to your normal diet straight after the test.
Annabelle is a registered dietitian who has a special interest in the complex interplay between gut health and mental health. In her NHS role, Annabelle specialises in mental health and learning disabilities, seeing patients in hospital for their mental health as well as supporting people in the community. Annabelle has also been working with the Food Treatment Clinic as one of our writers since she was a dietetics student.
Last updated on August 21st, 2023 at 08:36 pm