SIBO is an acronym that stands for “small intestine bacterial overgrowth.”
As the name suggests, this is where bacteria overgrows in the small intestine (where we don’t want it to), which has the potential to lead to digestive issues and imbalances. The majority of our ‘microbiome’ as it were, lives in our colon (the large intestine). Yes, there are some bacteria that live in the small intestine, but as the small intestine’s main function is to digest and absorb nutrients through its barrier, we don’t want a ton of bugs hanging around.
SIBO might be an overgrowth of the commensal, naturally occurring bacteria in the small intestine, or it could be due to a “backflow” so to speak, of bacteria from the colon, into the small intestine (see ileocecal valve dysfunction below, for more on this).
The bacteria that overgrow, produce gas as a byproduct of the fermentation process of food particles in the gut. This can lead to the production of methane, hydrogen, and/or hydrogen sulfide gases — which is how the SIBO ‘types’ are categorized.
This overgrowth can lead to a whole host of symptoms, most notably: bloating, gas, altered bowel movements (ie. constipation, diarrhea or both), and belching. It can also contribute to things like maldigestion, fatigue, systemic symptoms like joint pain, headaches, brain fog, and other symptoms associated with ‘leaky gut.’
In this article, we’re going to be doing a deep dive into some of the root causes that can contribute to SIBO.
Root Causes of SIBO
Let’s dig into some of the root causes of SIBO!
MMC (migrating motor complex) Dysfunction (Impaired Motility)
We’ve covered what the migrating motor complex is, and why its important in this article here (so make sure you check it out!), but to summarize: your migrating motor complex is an electromechanical process that occurs within the smooth muscle of the digestive tract.
Often referred to as the "janitor" or "housekeeper" of the gut, the MMC's job is to move along left-over particles and substances in the digestive tract, to be rid of via our stool.
The MMC is a very important motility function, that helps to 'clean up the gut' of any residual substances that we don't want hanging around.
When the MMC isn't functioning optimally, these substances are left to hang out in the gut. If there are food particles left to hangout in the digestive tract, the microbes in the gut are given the opportunity to feed on them, and to proliferate and produce excess gas as a byproduct of the fermentation process of these food particles.
MMC dysfunction can set the stage for bacteria to overgrow in the small intestine, leading of course to SIBO, and the associated symptoms.
To learn more about what can lead to MMC dysfunction, and how to improve on this, definitely check out this article.
Poor or impaired digestion can also lead to SIBO. Impaired digestion refers to things like low stomach acid production and secretion, poor bile output, and poor digestive enzyme output.
When we have low stomach acid output, we’ll see impaired protein digestion, potentially bugs that aren’t neutralized, and we may not get the ‘acid trigger’ that is required to communicate to the gallbladder and pancreas to secrete bile and enzymes respectively.
Bile is naturally anti-microbial and is secreted into the small intestine after food passes through the stomach to aid in fat digestion and absorption. Without enough of it, we may have an environment that can allow bacteria to overgrow.
Digestive enzymes secreted by the pancreas, into the small intestine, help us to break down nutrients so they can be absorbed through the intestinal lining. Without adequate enzymes, we may not be breaking down our food effectively, which can provide a feast for the microbes in the small intestine, allowing them to proliferate and overgrow!
In cases of SIBO, we need to ensure all of these digestive secretions are being produced and secreted adequately.
Ileocecal Valve Dysfunction
The ileocecal valve is the connection point between our small and large intestines — it’s a valve that opens and closes, allowing contents from the small intestine to enter into the large intestine, to be rid of from the body.
It’s located at the bottom of our right quadrant, somewhere in the middle between our belly button and our right hip bone (close to where your appendix is).
Dysfunction in this value, where it may not be opening or closing properly, can be an underlying cause of SIBO. If the opening and closing mechanism of this valve isn’t functioning well, it can allow backflow from the colon (where the majority of our gut microbiome lives), into the small intestine (where we don’t want large amounts of bacteria hanging out).
Working with a practitioner to see how nutrient status is impacting your ileocecal valve function, and perhaps a physical therapist like a chiropractor or osteopath can be good options for addressing this SIBO contributor.
Adhesions and Scar Tissue
Adhesions and scar tissue in the abdomen can also contribute to SIBO. Scar tissue in the pelvis, endometriosis, and adhesions as a result of surgical procedures in the area, can impact and obstruct outflow of contents from the small intestine into the large intestine.
Likewise, scar tissues and adhesions can impact the nervous system in the gut (the enteric nervous system), which plays a huge role in motility and the MMC, which we already covered above.
Both obstruction of the flow in the intestines, and an impacted enteric nervous system, can play a role in the development of SIBO.
Certain medications could play a role in the development of SIBO. PPI use (proton pump inhibitors) suppresses our stomach acid. As mentioned above, impaired digestion like low stomach acid levels can play a role in SIBO. Frequent antibiotic use can also lead to imbalances in the microbiome, which can create an opportunistic environment for bacteria to overgrow in the small intestine. Antispasmodics can impact our motility, which as we know can also be a contributor to the development of SIBO.
If you suspect you might have SIBO, and want to look further into healing your gut, then definitely check out my Gut Rehab Intensive.