Bloating that shows up every afternoon. Gas that clears a room. A stomach that looks six months pregnant by dinner. If that sounds familiar, someone has probably mentioned SIBO.
SIBO stands for small intestinal bacterial overgrowth. It means more bacteria are living in your small intestine than should be, and they're causing symptoms. The most common way to test for it is a breath test. Here's what that test can and can't tell you.
How the breath test works
You drink a sugar solution, usually glucose or lactulose, and breathe into tubes over the next couple of hours. If bacteria in your small intestine ferment that sugar, they release hydrogen or methane, and it shows up in your breath.
North American gastroenterology experts agreed on how to read it. A rise in hydrogen of 20 parts per million or more within 90 minutes counts as positive. A methane level of 10 parts per million or more counts as methane positive (North American Consensus, 2017).
Methane matters because it's linked with constipation. The American College of Gastroenterology suggests methane testing for people with constipation and now treats methane overgrowth as its own condition: intestinal methanogen overgrowth (ACG guideline, 2020).
What the test can't tell you
The breath test is useful, but it isn't perfect. The test that's often called the gold standard is a sample of fluid taken from your small intestine during an endoscopy. That's invasive, and even it isn't standardized (ACG guideline, 2020).
The guideline is upfront that the evidence behind breath testing is still very low quality. So a breath test result is one piece of the picture. It works best alongside your symptoms and your history.
Why SIBO keeps coming back
This is the part most people aren't told. In one study, 80 people were treated for SIBO and retested over the next nine months. It came back in about 13% by three months, 28% by six months, and 44% by nine months (Lauritano et al., 2008).
The people most likely to relapse were older, had their appendix removed, or were on long term acid blocking medication.
That tells you something important. SIBO usually isn't the root problem. Something let the bacteria build up in the first place: slow movement through the gut, a past surgery, a medication. If that cause is still there, the overgrowth tends to come back.
What about diet and probiotics?
The guideline says cutting back on foods that ferment easily is the main theme of diet changes for SIBO, but the research behind it is very low quality. It also says there isn't consistent data to recommend specific probiotics (ACG guideline, 2020).
That doesn't mean diet doesn't matter. It means a one size fits all SIBO diet off the internet isn't the answer.
How we approach it at FRI
We don't stop at the test result. We look at why the overgrowth happened, because that's what decides whether it stays gone. That means your full history, your medications, and the right labs for your symptoms.
We take a natural, whole body approach and don't prescribe medications. If antibiotics turn out to be the right call, we refer you to a medical physician and stay involved, so your care is managed together.
If you've been treated for SIBO and it keeps coming back, book a complimentary 20 minute consultation. We'll hear your story and decide together which labs actually make sense.
Sources
- Rezaie A, et al. Hydrogen and Methane Based Breath Testing in Gastrointestinal Disorders: The North American Consensus. Am J Gastroenterol. 2017;112(5):775–784. Link
- Pimentel M, Saad RJ, Long MD, Rao SSC. ACG Clinical Guideline: Small Intestinal Bacterial Overgrowth. Am J Gastroenterol. 2020. Link
- Lauritano EC, et al. Small intestinal bacterial overgrowth recurrence after antibiotic therapy. Am J Gastroenterol. 2008;103(8):2031–2035. Link