Dealing with digestive issues can be frustrating, especially when the answers aren’t clear. If you’ve recently taken a SIBO breath test, you might be staring at a series of numbers and wondering. “What do these results actually mean?” Don’t worry—you’re not alone!
The SIBO breath test is a widely used diagnostic tool for identifying Small Intestinal Bacterial Overgrowth (SIBO). By measuring gases like hydrogen, methane, and, in advanced tests like the Trio-Smart test, hydrogen sulfide, it helps uncover what’s happening in your small intestine.
But understanding these gas levels and patterns isn’t always straightforward. In this post, we’ll simplify the results, explain what hydrogen, methane, and hydrogen sulfide levels indicate, and show you what steps to take next. Whether you’re interpreting your results for the first time or seeking clarity, this guide has you covered. Let’s dive in! 🚀
How do you diagnose SIBO?
Small Intestinal Bacterial Overgrowth is a gut condition that occurs when there are too many bacteria in the small intestine. Since the small intestine usually only has a few bacteria, this may lead to early fermentation and gas production. In turn, this causes a myriad of uncomfortable bowel symptoms like bloating, diarrhea/constipation, and even mental issues.
Your doctor might suggest a few tests to determine if you have SIBO. These tests can help uncover whether there’s too much bacterial activity in your small intestine, if you’re not absorbing fats properly, or if something else might be causing your symptoms. The most common one is a breath test.
Breath testing
This is one of the most popular and noninvasive ways to check for SIBO. After a specific diet, you’ll drink a glucose-water mixture, then breathe into a series of tubes over three hours. The test measures hydrogen and methane levels in your breath. If there are bacteria in your small intestine, they will release gases as they ferment sugars in your gut. This is measurable on your breath! Sometimes hydrogen sulfide is also tested. A sharp rise in these gases might suggest bacterial overgrowth. While it’s convenient and widely used, it’s not the most precise test out there (1).
The steps of a SIBO breath test:
- Before the test, you need to adhere to a strict diet to avoid specific food interfering with the results. In my case, I could only eat egg + plain white rice 24 hours before the test and nothing at all starting 12 hours before the test. Also, it’s important to discuss any medication you take with your healthcare provider. Especially antibiotics should not be taken for 2 weeks before the test, because they can mess with the results!
- You get a sugar solution at the start of the test. It’s exceptionally sweet, but it’s only a small amount so it’s fine.
- During the test, your breath samples are checked every 20 minutes to measure hydrogen, methane, and sometimes hydrogen sulfide levels. These are reported in parts per million (ppm) to show how much gas your gut bacteria are producing. I did the test at home and could just breathe into a test bag. The test clearly stated to not be afraid if you don’t see the bag inflating, they can still measure it.
Do you have to have symptoms during the test for it to come out positive?
No, some people respond to the sugary solution and others do not have significant bloating or pain. My body already felt out of whack due to the uncommon diet the days before and I got diarrhea quite quickly after drinking the sugary solution. But even if you don’t have that, you might still have SIBO.
Other diagnostic tools & tests
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Small Intestine Aspirate and Fluid Culture: This test used to be considered the gold standard for diagnosing SIBO. It involves collecting a sample of fluid from your small intestine and checking it for bacterial overgrowth. The problem? It’s easy for the sample to get contaminated by bacteria from your mouth, leading to unreliable results. These days, most experts don’t recommend it anymore.
- Blood Tests: These can check for vitamin deficiencies linked to poor nutrient absorption.
- Stool Tests: Helpful for spotting fat malabsorption and other digestive issues.
- Imaging Scans (X-rays, CT scans, or MRIs): These can reveal structural problems in your small intestine that might be contributing to your symptoms, like blockages or adhesions.
SIBO breath test results
In a normal result, gas levels stay pretty stable throughout the test, meaning you don’t have SIBO. In an abnormal result, you’ll notice clear spikes in hydrogen, methane, or hydrogen sulfide at specific points, which could point to bacterial activity where it shouldn’t be.
Why Timing Matters:
- Early Spikes (0–30 minutes): If gas levels rise early in the test, it usually means bacteria in your small intestine are fermenting the sugar—this suggests SIBO.
- Late Spikes (After 90 minutes): A late rise in gas is more likely due to bacteria in your large intestine, not SIBO.
In short, it’s not just how much gas is produced, but also when it’s produced that helps determine whether you’re dealing with SIBO or something else.
Hydrogen SIBO
A significant increase in hydrogen levels (typically >20 ppm above baseline) within the first 90 minutes of the test indicates hydrogen-dominant SIBO.
Methane SIBO (IMO)
Hydrogen Sulfide SIBO
Hydrogen sulfide is a gas produced by specific bacteria and can only be detected using advanced tests like the Trio-Smart test. Abnormally high levels (more than 3 ppm) can indicate hydrogen sulfide-dominant SIBO, which often presents with diarrhea, sulfur-like odors, and intestinal inflammation.
What Happens If the Numbers Are High From the Start?
Breath testing for SIBO has its fair share of limitations. If hydrogen, methane, or hydrogen sulfide levels are high at baseline (before you drink the sugary solution), it may suggest one of the following:
- Small Intestinal Stasis: Food and bacteria are lingering in the small intestine.
- Recent Meal Interference: You may not have followed pre-test fasting guidelines properly. Only you will know if that is the case.
- One challenge with SIBO breath tests is that Oral-Cecal Transit Time (OCTT) can vary a lot. Sometimes, an early spike in hydrogen might actually come from the colon, not the small intestine, though the small intestine is usually the main culprit (1).
False positives are also an issue, especially in people who’ve had upper GI surgery. Changes in how food moves through their digestive system can mess with glucose test results, showing a positive result whereas there is no SIBO. While scintigraphy—a medical imaging technique that tracks how substances move through your digestive system—can help clarify breath test results, it’s not always practical.
On the flip side, false negatives happen too. If the sugar solution doesn’t reach the small intestine (like in gastroparesis) or methane-producing bacteria consume the hydrogen before it’s measured, the test might miss SIBO entirely even though it’s a SIBO case!
So what can you do in this case? As frustrating as it may be, only you know if you did the test preparation well, if you are in doubt, it might be a good idea to redo the test. If you’re absolutely sure you did it right, your doctor might decide to deal with SIBO based on symptoms rather than a diagnosis or they might try to rule out other conditions before coming back to SIBO.
Mixed Gas Patterns and What They Mean
When both hydrogen and methane levels are elevated on a SIBO breath test, it suggests a mixed SIBO pattern, meaning both hydrogen and methane-producing bacteria are present. This can lead to a mix of symptoms, like diarrhea from hydrogen and constipation from methane.
This combination is tricky to find, because methane-producing archaea ‘eat’ hydrogen, so it might not be visible on the breath test. Effective treatment usually involves a combination of antibiotics (like rifaximin and neomycin) or herbal antimicrobials to target both types of bacteria. Read more about it here.
Next Steps After Receiving Your Results
After receiving your SIBO breath test results, it’s important to consult a doctor who specializes in gut health or a functional doctor who treats the body holistically. Treatment options may include antibiotics like rifaximin for hydrogen-dominant SIBO or a combination with neomycin for methane types. Alternatively, herbal therapies such as oregano oil, berberine, and garlic extracts can be effective.
Finally, retesting after treatment helps ensure bacterial levels are back to normal. Although my doctor actually suggested not to do a retest. She mentioned that if I would feel better, a retest made no sense and it is too expensive to just do for fun. (I completely agreed!)
Conclusion
Navigating SIBO breath test results might seem tricky at first, but with a clear understanding of hydrogen, methane, and hydrogen sulfide levels, you’re equipped to take control of your gut health. Understanding your results is key to getting the right treatment, and teaming up with a healthcare professional makes sure you’re on the right path.
