The SIBO Testing Mistake I See All The Time (And How To Test For This Common Condition The Right Way)
Last week I had a consultation with a new patient who had the gut symptoms I see all the time: bloating, food intolerances, and bowel disturbances (yes, I’m talking constipation and diarrhea!).
After hearing her entire health history, I asked if she had ever been tested for SIBO (Small Intestine Bacterial Overgrowth).
“No, that’s not it” - she told me - “I had a stool test that was negative for SIBO.”
Major. Red. Flag.
This is a HUGE misconception - but stool tests cannot diagnose OR rule out SIBO.
I don’t blame this woman or her doctor for being confused. Even great practitioners are often unsure what tests can and can’t diagnose SIBO.
This is really important because with the right testing... SIBO can be treated and resolved, most of the time.
That means you can say goodbye to the bloating and gas (for good) and get back to enjoying life.
If you’ve got digestive complaints - even (and especially) if you’ve been told you don’t have SIBO before - this blog post is for you. Let’s clear up all the misconceptions about SIBO testing so you can get on the road to healing.
What Is SIBO?
Small Intestine Bacterial Overgrowth (SIBO) occurs when bacteria overgrow in the small intestine. Normally, there should be very few bacteria in the small intestine - instead, bacteria should live in the large intestine.
When bacteria overgrow in the small intestine, those bacteria can feast on undigested food as it leaves the stomach and enters the small intestine. As the bacteria eat, they produce gas (hydrogen, methane, and hydrogen sulfide) and that gas causes symptoms like diarrhea, constipation, and bloating.
So why do they overgrow? There are tons of reasons - but some of the most common reasons I see are:
- Endometriosis (which can cause sticky scars, called adhesions, inside that prevent the normal flow of bacteria)
- Certain medications that slow down the digestive system (opioids are a common culprit)
- Past food poisoning (which can trigger an autoimmune reaction that impacts motility)
If you’ve never heard of SIBO, you might think it sounds really rare or unusual… but it is very common. About one billion people worldwide have “Irritable Bowel Syndrome” - and of those, 60% are believed to actually have SIBO as a result of post-infectious IBS - which puts the estimate at about 600 Million people with SIBO!
Why Having SIBO Can Be Good News
The truth is I LOVE seeing a positive result on a SIBO breath test… not only does it explain why a patient has been dealing with symptoms (often for years)... but it is also a problem we can usually fix.
Depending on the type and severity of SIBO, it can be resolved in as little as one treatment cycle.
But successful treatment is wholly dependent on testing, since different types of SIBO require different treatments.
That’s why SIBO really requires not just an accurate test - but a practitioner who can interpret the results and create a customized treatment plan based on them.
Why Stool Tests Can’t Diagnose SIBO
To put it simply, stool tests are looking at the wrong part of the body. Stool tests tell us mostly what is happening in the large intestine - not the small!
So while it is possible that some of the organisms we see in stool testing are living in the small intestine, the results we get are more reflective of the large intestine.
Furthermore, while there can be some indicators that SIBO is likely from stool testing results, it's impossible to differentiate small vs. large intestine.
Stool tests can be really useful for diagnosing many other conditions - parasites, enzyme deficiency, and more - but they are not able to determine if bacteria is overgrown in the small intestine.
I love stool tests - and if you’re coming to me with gut issues, I almost always order a stool test - but it won’t tell you if you have SIBO!
Urine Organic Acids Tests Don’t Work Either
The urine organic acids test is another popular and really useful test - unless you want to diagnose SIBO.
The organic acids test can indicate if a bacterial overgrowth is present, but the problem is it can’t differentiate between the small and large intestine.
(Yes, Large Intestine Bacterial Overgrowth (LIBO) is a thing too!)
If you don’t know where the overgrowth is, you don’t know which treatment to use.
Again, this is a really useful test (and one I often use for other conditions) but it can’t diagnose SIBO.
The Right Way To Test For SIBO
There are 2 ways to test for SIBO properly:
- Endoscopy with culture (not commonly used anymore)
- Breath test (the gold standard and what I use)
(There is also a blood test for post-infectious IBS (which is a form of autoimmune IBS caused by food poisoning) that can be used, since most people with post-infectious IBS have SIBO. I use this if a breath test was inconclusive.)
The breath test is far and away the most simple, accurate, and useful of these tests, and it’s what I alway use with my clients.
That being said... Even though the breath test is the best, it doesn’t mean it’s perfect.
The breath test works by measuring hydrogen and methane gas in your breath after a special 24-hour prep diet and consuming a sugar solution (aka the test substrate). There are two options: glucose or lactulose.
The glucose test is only able to diagnose SIBO in the beginning of the small intestine (the small intestine can be over 20 feet long!). Because glucose is rapidly absorbed in the intestine, it isn’t good for finding SIBO that is farther down the small intestine.
The lactulose breath test can diagnose SIBO in any part of the small intestine, but it does have a higher rate of false positives.
Glucose is more likely to miss some cases of SIBO, but the ones it does identify are more likely to be true positive diagnoses.
Therefore, I sometimes run glucose and lactulose tests side by side to get a more complete picture.
Why The Right Test Matters So Much
I’ve said it before, but it’s so important that I will repeat it now: in SIBO, testing guides the treatment.
Depending on which gases are detected in your breath, and at what levels, treatment will differ.
That’s why it’s also really key to have help interpreting a test from a skilled practitioner. SIBO breath test results aren’t a simple “positive” or “negative” - you’ll get a graph that shows different gas levels at different points in the test.
If you’ve never seen them before, these graphs are confusing and overwhelming. But to someone who knows what they’re looking at, your breath tests results are like a map to healing your SIBO and resolving your symptoms.
Bottom line: if you suspect SIBO, get a breath test!
Get Help With SIBO
SIBO is a really complex condition (let’s not sugar coat it!). But it’s not incurable… and if you DO have it, resolving SIBO might be the answer to years of uncomfortable gut symptoms.
Every case of SIBO requires personalized treatment, but that’s part of why I love my job - helping you put the pieces of your health puzzle together and achieve your goals is my purpose in life!
I’ve helped hundreds of people diagnose and resolve SIBO… and I’d love to help you, too! There’s no need to make a commitment right now - book a free 15-minute consultation with my team to learn about how we could help you and what options you have here ---> Book a Free 15-Minute Consult
