SIBO BREATH TESTING: What It Is, How It Works, and Why It Matters

If you're navigating persistent bloating, abdominal discomfort, or unpredictable digestion, there's a good chance your symptoms may be linked to small intestinal bacterial overgrowth, or SIBO. This condition occurs when bacteria that are normally found in other parts of the digestive tract begin to colonize the small intestine, where they don’t belong. As a naturopathic doctor with a focus on digestive health, I often use SIBO breath testing as a non-invasive and reliable way to uncover this imbalance and help patients finally get answers.

Let’s walk through what the SIBO breath test is, how it works, and what the results mean for your health.

What Is the SIBO Breath Test?

The SIBO breath test is a diagnostic tool we use to identify bacterial overgrowth in the small intestine. Unlike the colon, the small intestine is meant to have relatively low bacterial levels. When that balance shifts—often due to underlying motility issues, infections, or other gut disruptions—bacteria begin fermenting carbohydrates too early in the digestive process. This fermentation produces gases that can be detected in your breath.

The two primary gases we test for are hydrogen and methane. These gases are produced by different types of bacteria:

• Hydrogen-producing bacteria are more likely to cause symptoms like bloating, gas, and diarrhea.

• Methane-producing organisms (technically archaea) are often associated with constipation and slowed gut motility.

• Hydrogen sulphide is a third gas that is not part of a standard SIBO test, but can be tested via the TrioSmart Breath test (not yet available in Ontario)

Elevated levels of either gas can indicate an overgrowth in the small intestine, and help us tailor your treatment accordingly.

How Is the SIBO Breath Test Done?

One of the benefits of SIBO breath testing is that it's simple and non-invasive. Here’s what to expect:

1. Pre-Test Preparation: For the most accurate results, you’ll follow a specific preparation protocol. This usually includes:

   • A restricted diet 24-48 hours (determined by your doctor) before the test (typically consisting of white rice, eggs, fish, chicken, water and black coffee/plain tea).

   • A 12-hour overnight fast before testing.

   • No probiotics, antibiotics, or certain laxatives for at least 1–2 weeks before your test (depending on the type).

     
     

2. The Test Itself: The test can be done either at home with a kit or in-clinic. You'll begin by collecting a baseline breath sample, then drink a sugar solution—typically lactulose or glucose:

   • Lactulose is a synthetic sugar that isn’t absorbed in the small intestine, so it continues to move through the digestive tract and interacts with bacteria along the way. It's helpful for identifying overgrowth throughout the small intestine.

   • Glucose is absorbed more quickly in the upper small intestine, and is better for detecting overgrowth in the early segments. It generally is considered less likely to create false positives.

     
     

3. Breath Collection: After drinking the solution, you’ll collect breath samples at regular intervals (usually every 20 minutes) for up to three hours. Each sample is analyzed for hydrogen and methane gas levels.

Understanding Your Results

Once your test is complete, we'll review your gas readings over time to identify patterns that may suggest bacterial overgrowth:

• Elevated Hydrogen Levels: This often reflects carbohydrate fermentation by hydrogen-producing bacteria. It’s most commonly associated with bloating, gas, and loose stools.

• Elevated Methane Levels: Suggests methane-dominant SIBO, which can slow intestinal transit and contribute to constipation.

• Flat-Line or Normal Results: A flat line may suggest hydrogen sulphide SIBO (which current tests don't detect), or it may indicate no bacterial overgrowth, prompting us to look at other potential causes of your symptoms.

  
  

Correct interpretation of your results is key to effective treatment. I always take into account your symptom picture, health history, and testing timeline to ensure we’re addressing the true root cause.

Why Work With a Naturopathic Doctor for SIBO Testing and Treatment?

In my practice, digestive health isn’t just about symptom management—it’s about getting to the root. If you're experiencing chronic bloating, irregular stools, or unresolved gut discomfort, the SIBO breath test may be a critical step in understanding why.

What sets my approach apart is the integration of advanced testing with personalized, natural treatment protocols. If your test is positive, we'll work together to develop a plan that may include herbal antimicrobials, diet modifications, motility support, and gut healing strategies.

If you’re in Ontario and suspect SIBO may be impacting your health, we invite you to reach out. You don’t have to live with digestive discomfort—answers (and solutions) are possible. Note, SIBO testing can only be ordered for patients of Dr. Holmberg, so an initial appointment is necessary prior to ordering any testing.

📞 Call (647) 351-7282 to visit the calendar to book your appointment with Toronto Naturopathic Doctor, Dr. Courtney Holmberg, ND.