Do you know how it feels to consult your gastroenterologist seeking answers about your digestive distress, only to be run through invasive tests like a colonoscopies or endoscopies, declared “normal” and sent away?
Thankfully, Irritable Bowel Syndrome (IBS), as a collection of non-specific digestive symptoms that don’t qualify as an irritable bowel disease like Crohn’s, has begun to finally permeate mainstream medical knowledge over the past few years.
SIBO (small intestinal bacterial overgrowth) is the most common underlying cause of IBS (for example, between 76-84% of IBS patients were shown to have SIBO in this study). Unfortunately, many doctors still do not recognize SIBO as a diagnosable condition.
When you do find a gastroenterologist who will recognize SIBO, you will often receive standard treatments such as a round of antibiotics. For some patients, this works. For many others, though, it’s insufficient.
That’s because approaches like this are not addressing the root cause, but rather taking aim at the final manifestation of that root issue, which is the bacterial overgrowth. Treating a condition at a superficial level like this does not always work, and relapse rates are high.
Functional medicine aims to identify and reconcile the root cause, not just put a band-aid over symptoms to make them go away temporarily. A functional approach to SIBO prioritizes diving deeper into how your body works and finding that root cause, so that healing can come full circle.
What is small intestinal bacterial overgrowth (SIBO)?
Small Intestinal Bacterial Overgrowth (SIBO) happens when bacteria from the large intestine migrate upwards and populate the small intestine. This is a problem because the concentration of bacteria in the small intestine should be much lower than in the large intestine, and problems arise when this is not the case.
The small intestine is responsible for digestion and nutrient absorption, and when bacteria overpopulate this area, they interfere with those processes. This can lead to a range of gastrointestinal symptoms, such as bloating, pain, constipation, and diarrhea. The problem is the location of the bacteria, not the bacteria themselves.
Why does understanding your root cause matter?
By understanding the underlying causes, we can better manage and treat SIBO.
To understand the causes, and ultimately heal the gut for good, we need to split hairs about the difference between what aggravates or causes SIBO symptoms, and what actually causes the bacterial overgrowth condition of SIBO itself in the first place.
There is much talk about FODMAPs (a group of fermentable carbohydrates found in a variety of foods, including many healthy fruits and vegetables) in relation to treating SIBO, but unfortunately, a lot of it centers around avoiding FODMAPS indefinitely as a cure for SIBO, as though the FODMAP consumption was the cause.
A low-FODMAP diet can be a valuable nutritional therapy for those with SIBO to manage their symptoms while they identify the root case. However, we should not equate it with a cure, nor FODMAP-abundant foods as the cause. That garlic in your favorite bolognese, though it may aggravate your symptoms, is not the cause of your SIBO. The real cause of your SIBO is whatever is impairing your small intestine so that it doesn’t have the correct ratio of bacteria to properly break down high-FODMAP foods.
No one should accept a life of forever counting out their almonds to make sure the quantity doesn’t inch from “low” into “moderate” FODMAP territory.
Everyone deserves to achieve a balanced, resilient microbiome that can allow you to enjoy a satisfying diet by breaking down and utilizing nutrients from an array of FODMAP-rich, healthful whole foods.
It isn’t always obvious what your personal root cause may be, and many people need to seek professional help from a provider trained in root cause medicine to uncover it.
Here is a breakdown of possible causes to get you started.
The 2 underlying physiologic causes of SIBO
The two most common causes of the small intestine not being able to protect against bacterial colonization are:
- Impaired motility in the small intestine: This refers to a dysfunction in the normal movement of the small intestine, which is responsible for propelling food, bacteria, and waste through the digestive system. When motility is impaired, bacteria in the small intestine can proliferate because the natural process of clearing it is disrupted. Under normal conditions, the small intestine is propelled by a “cleansing wave” of rhythmic contractions known as the migrating motor complex (MMC). These waves help move food, waste, and bacteria towards the colon in preparation for elimination from the body in the form of a bowel movement. When the body’s migrating motor complex is impaired, all that waste trying to make it out of your system gets stopped up in your intestines on its way through the digestive tract. This can lead to bacterial proliferation in the small intestine and ultimately overgrowth.
- Structural/anatomic abnormalities: Any physical changes or abnormalities in the small intestine that impair the flow of digestive contents can contribute to SIBO. This includes conditions like intestinal strictures, adhesions (scar tissue from previous surgeries), or diverticula. These abnormalities can create “pockets” where bacteria can accumulate and grow excessively. Research suggests that patients who have undergone abdominal surgery or those with chronic conditions like Crohn’s disease or celiac disease, which affect the integrity of the digestive tract, are at a higher risk for developing SIBO due to these structural abnormalities.
Impaired motility is the most common cause of SIBO
So, what causes impaired motility?
Impaired motility that leads to SIBO is most often caused by a bacterial food poisoning event, like travelers diarrhea or the stomach flu. SIBO can manifest months after the poisoning.
There are many other possible causes of impaired motility, such as:
- Excessive broad-spectrum antibiotic use can kill beneficial gut bacteria along with the bad, which can lead to an overgrowth of opportunistic pathological microbes.
- Neurological issues, such as dysfunction in the enteric nervous system (the “gut brain”) can impair the nerve signaling responsible for initiating the MMC. This includes conditions like Parkinson’s disease, autonomic neuropathy, and vagal nerve dysfunction.
- Chronic stress and anxiety often cause high levels of the hormone cortisol, which can interfere with the normal functioning of the MMC. These mental health conditions also can impair serotonin signaling in the gut, which is why SSRIs are being shown to be an effective SIBO treatment.
- Both type 1 and type 2 diabetes can cause diabetic autonomic neuropathy, which affects the autonomic nervous system’s ability to regulate motility.
- Imbalances in hormones that influence gut motility such as ghrelin and motilin can lead to disruptions in the motor complex.
- Conditions such as gastroparesis, intestinal pseudo-obstruction, and scleroderma. Studies show that gastroparesis, for example, is associated with an almost 50% prevalence of SIBO.
- A poor diet, particularly one high in processed foods, refined sugars, and fats, can negatively affect the gut microbiome and MMC function.
- As people age, changes in muscle tone and nerve function in the gut can lead to a slower or less effective MMC.
Summary
When standard approaches to treatment don’t work, understanding your personal root cause of SIBO is important to determine effective treatment.
Impaired motility and structural issues are at the root of many SIBO cases, with impaired motility having various possible root causes of its own.
Determining your root cause can be a complex and involved process, and often testing and personalized medical or dietary treatment is necessary.