IBS and SIBO: Could SIBO be the Cause of Your IBS Symptoms?
IBS (irritable bowel syndrome) is the most commonly diagnosed gastrointestinal condition 💩
Which definitely tracks with the client base I work with, as the majority of my clients come to me having had an IBS diagnosis in the past.
The thing, though, with IBS is — it tends to be a “catch-all” diagnosis.
One where most other GI conditions are ruled out via labs and screenings like x-rays, ultrasounds, colonoscopies, and endoscopies.
And doctors are like — “Welp, we’ve ruled out x, y, and z.. looks like you’ve got IBS 😬”
If you’re an IBS sufferer, here’s what might not be on your radar:
(the jury is still out and we’re still learning the full implications of this, but)
Many studies show the prevalence of SIBO (small intestine bacterial overgrowth) in folks who have IBS.
Which leads to the question: could SIBO be one of the potential root causes of your IBS symptoms?
Perhaps.
As a reminder, our small intestine is where we digest our food and absorb the majority of our nutrients. Its main function is digestion and absorption.
Our large intestine is where the majority of the gut microbiome lives — the collection of trillions of microbes that benefit us in so many ways 🦠
Compared to our large intestine, our small intestine houses a fraction of the microbial population.
Hence “small intestine bacterial overgrowth” in SIBO. There is an overgrowth of bacteria and microorganisms where they shouldn’t be (even if they’re “beneficial” microbes; or microbes normally found in the small intestine).
It’s this overgrowth that’s super problematic, and can lead to a variety of symptoms 🙃
Let’s explore SIBO a little further👇
The Different Types of SIBO
There are three different types of SIBO, that involve different species of microorganisms, and often present with different symptoms:
SIBO-H
IMO
SIBO-H2S
SIBO-H (Hydrogen SIBO)
Hydrogen SIBO is referred to as such because the bacteria involved in this presentation are hydrogen producers. An overgrowth of specific hydrogen-producing bacteria in the gut will increase gas production, often contributing to symptoms associated with IBS-D (like loose stool/diarrhea).
What’s interesting about this type of SIBO is that hydrogen gas can actually FEED other microbes that produce gases like methane. Therefore this type of SIBO can promote other overgrowth in the small intestine (ie. you might see both hydrogen AND methane SIBO) 😅
IMO (Intestinal Methanogen Overgrowth, formerly referred to as Methane SIBO)
This type of intestinal overgrowth used to be referred to as Methane SIBO — but it’s since been changed to IMO (intestinal methanogen overgrowth) because it’s not actually a bacteria that is the methane producer in this presentation, but microbes known as ‘archaea.’
This type of dysbiosis (which can occur in the small OR large intestine), is often associated with constipation presentations. The methane produced by archaea acts as a local ‘paralytic’ in the GI tract, which can impact motility (how things move through the gut), and lead to constipation.
SIBO-H2S (Hydrogen Sulfide SIBO)
Hydrogen sulfide SIBO (H2S) is less common than the other two. BUT if you know this one — you know this one 🙃 The gas produced in this presentation — sulfurous gas — is responsible for the farts or poop that smells like rotten eggs 🍳 Not cute.
What’s also not cute about this type of SIBO (though none of them are), is that often people will experience a mix of diarrhea and loose stool, and constipation. A more IBS-M presentation.
Symptoms of SIBO
In case you’re wondering what common symptoms of SIBO look like, let’s dive into that here (you may or may not be surprised to see that they very much correlate with common IBS symptoms 🤪).
Symptoms of SIBO might be things like:
bloating (often significant, and with distention), around 1-2 hours after meals (I find this one to be the most prevalent!)
altered bowel movements (constipation, diarrhea, or a mix of both — see above for the different types of SIBO associated with different bowel movement patterns)
cramping and abdominal pain
upper GI symptoms like burping, reflux, indigestion
PLUS there are a number of symptoms outside of the GI tract that can correlate to SIBO.. things like joint pain, fatigue, fibromyalgia, skin issues, nutrient deficiencies, and more
The Why: Common Causes of SIBO
As I’m sure you can imagine — there are many different reasons that SIBO can occur in a person.
Let’s cover some of the common ones:
Altered Motility
When stuff isn’t moving through our guts in an effective, efficient manner — our gut can become an environment more conducive to the development of SIBO.
If the migrating motor complex (which you can learn more about here), is compromised, and contents aren’t being moved from the small intestine > to the large intestine efficiently, fibers and remnants of our foods can feed bacterial populations in the small intestine leading to an overgrowth.
Motility and the migrating motor complex can be impacted by several things:
Poor/dehydration. Ensure you’re hydrating well with minerals (electrolytes like potassium, magnesium, and sodium are important for healthy motility and bowel movements).
Lack of movement; sedentary lifestyle
Low thyroid function/hypothyroidism
Impacted vagal tone
Chronic stress
and more
Poor Digestive Function
Poor digestive function like low stomach acid production (or hypochlorhydria), poor bile flow/output, etc., can have a huge impact on microbial populations throughout our digestive system and can play a role in the development of SIBO.
Stomach acid is a digestive secretion produced and secreted in the stomach (😅). Its primary roles are: digestion (helping to break down our food; especially protein breakdown!), stimulating the digestive cascade, and protecting us against foreign invaders that we may ingest 🪱🦠
Inadequate stomach acid levels may leave us susceptible to translocation of bacteria (like in the instance of our oral cavity > our gut), and compromise the rest of our digestive cascade (like bile and enzyme secretion), which may play a role in the development of SIBO in some cases.
Bile is a substance produced in the liver, and stored and concentrated in the gallbladder. It has many roles in the body, some of which are breaking down & emulsifying fats, aiding in the absorption of fat-soluble nutrients (like A, D, E, K), promoting healthy motility due to its natural laxative-like effects, and keeping our microbiome balanced due to its natural anti-microbial properties.
Inadequate bile production and secretion may lead us more susceptible to developing SIBO due to its roles in microbial balance and motility.
Medication Use
Certain medications — like PPIs (proton pump inhibitors), medications that impact/slow motility (like antibiotics for example) — can impact our digestive processes, our motility, and ultimately bacterial populations. All things that can set the stage for SIBO 👋
Chronic Stress
Stress can contribute to.. a whole whack of digestive issues (AND a whole whack of issues outside of the digestive system, too). The stress response actively shuts down digestion in the moment, prioritizing vital bodily functions needed to address the stressor. Long-term, chronic stress can seriously impact our digestive function, microbial balance, motility, and more.
Ileocecal Valve Dysfunction
The ileocecal valve is a sphincter that connects our small intestine to our cecum (the first part of our large intestine). It’s located in the area between your right hip bone and your belly button — the lower right quadrant of your abdomen!
This valve is designed to have a one-way flow, from the small intestine TO the large intestine, ensuring that remnants from digestion in the small intestine can make their way to the colon.
A faulty valve increases the potential that bacteria from the colon (where the majority of our microbiome lives) to translocate into the small intestine, leading to SIBO.
Structural Issues
Adhesions, scar tissue, endometriosis, a history of surgery in the abdominal cavity, etc., can all increase the risk for the development of SIBO.
Similar to some of the SIBO root causes above, structural issues can impact digestive function, motility, ileocecal valve function, and microbial balance.
Testing for SIBO
As far as testing for SIBO goes (we love to test, not guess!) — the gold standard ⭐️ test for it right now is a breath test.
This is an at-home test that you can access, to test for the different types of gas (like methane and hydrogen), that can be indicative of overgrowth in the small intestine.
There are a few different tests available to test for SIBO, using various substrates — glucose. lactulose, and the Trio Smart. Your practitioner can help you determine which test is best suited for you based on your symptoms, case presentation, accessibility, etc.
While stool tests (like the one I love to run with clients — the GI MAP — can provide us with clues that may point to SIBO, it’s not a great way to properly identify SIBO (especially not which type it is, which helps identify an eradication plan).
(partial sample report of a lactulose breath test from Genova Diagnostics)
Next Steps for you and your IBS and/or SIBO Journey
SO.
If you’ve been diagnosed with IBS (or suspect you have it), and you’re questioning whether or not SIBO may be at the root of your symptoms.. here are some things you can start doing right now at home, to support yourself and your gut while you investigate further:
Space your meals ~3-4 hours apart. Eating more frequently, for most people, can impact our motility (the way things move through our digestive tract). Poor migrating motor function — the wave-like motion that moves stuff like undigested food and bacteria from our small intestine > to our large intestine — can be a major contributor to SIBO. And leaving 3-4 hours between meals to let our MMC do its job can be a great step in the right direction!
Try digestive bitters to support stomach acid levels, digestive function, and liver and gallbladder health. Poor digestion, low stomach acid, and poor bile output can all contribute to SIBO. Bitters are a generally safe (always check with your provider before supplementing!!) way to support your digestive processes.
Experiment with a low FODMAP diet for 2-3 weeks. OK. I generally don’t love recommending restrictive diets.. it’s not often a part of my MO (I’ve done them, my clients have done them.. they generally suck to do lol).
BUT there’s time and place. Doing a therapeutic low FODMAP diet for 2-3 weeks ONLY, as an experiment, is a great way to identify whether it might be worth exploring SIBO and other digestive imbalances more deeply.
This is a therapeutic diet that’s often recommended both by the allopathic, and functional medicine communities as a means of managing IBS and SIBO-related symptoms. It’s a diet that effectively removes a ton of highly fermentable short-chain carbohydrates (the acronym, FODMAP, refers to these fermentable constituents: Fermentable Oligosaccharides Disaccharides Monosaccharides and Polyols), therefore reducing symptoms associated with SIBO and IBS.
As always — it’s very seldom that the foods we’re eating are the actually root-cause problem, so diets such as this one are meant as short-term interventions to aid in therapeutic protocols or provide relief from symptoms, WHILE you work on investigating & rectifying the root-cause of your symptoms.
Looking for Help with your IBS and/or SIBO?
If you suspect you might have IBS — even SIBO — and you’re interested in functional labwork to look deeper into what’s going on, I’m here to help 👋
Inside my 1:1 program the Gut Restore Method I help clients take an investigative, root-cause approach to determining what is going on with their gut health 🙃
We use functional labs (as appropriate) to gain deeper insight into what’s going on in your gut, help inform our steps moving forward — while working on addressing root-causes that may be at play for you, and building a strong health-conducive foundation to support you and your gut health long term (well beyond we wrap up our work together).
If you’d like to learn more about this high-touch 1:1 program, you can do so here.
