SIBO or IBS: Finding the True Cause of your Gut Symptoms
by Dr. Megan Taylor
In my prior post “Understanding the Root Cause of Your IBS”, I talked about the various underlying causes of Irritable Bowel Syndrome (IBS). Today, I want to talk about one of the most common underlying causes of IBS symptoms, which is actually an entirely separate condition called Small Intestinal Bacterial Overgrowth (SIBO). Based on some studies, up to 3/4 of IBS patients may actually have SIBO (1). Treating this bacterial overgrowth can lead to significant symptom improvement in many patients.
What is SIBO?
The intestines are home to many millions and billions of microorganisms, but these organisms should be mostly limited to the large intestine. When bacteria accumulate and replicate in the small intestine, beyond what is normally found there, we develop small intestine bacterial overgrowth or SIBO.
How does SIBO cause the symptoms of IBS?
Intestinal bacteria normally digest and ferment the food we consume primarily in our large intestine, and provide us with all sorts of good things - like short chain fatty acids, vitamins, etc - in the process.
In SIBO, the bacteria now ferment the food we consume in the small intestine, as well as the large intestine. This fermentation process produces gas (think yeast fermenting sugar to produce carbonated alcohol) and when fermented in the small intestine, this gas has nowhere to go! As the gas builds, it can cause pain, bloating or distention, and can contribute to diarrhea or constipation. These are also symptoms of irritable bowel syndrome or IBS.
How do I know if I have SIBO?
One of the single most recognizable symptoms of SIBO is intestinal bloating - we are talking extreme, "like-I-am-10-months-pregnant" type of bloating that typically is better in the morning and worse as the day progresses. It can be anywhere from mildly uncomfortable to incredibly painful, and is often triggered by meals containing highly fermentable foods such as lactose-containing dairy, beans and legumes, brassicas, etc. While not everyone will have significant bloating, the complete absence of bloating often leads me to wonder what else might be contributing to patients symptoms. Folks with SIBO will also typically have some changes in bowel habits (diarrhea or loose stools are common, though constipation can occur).
Check out my mentor, Dr. Allison Siebecker’s site, SIBOinfo.com, for other signs and symptoms of SIBO, as well as associated conditions.
How is SIBO diagnosed and treated?
In order to have the appropriate information to make an accurate diagnosis, you will want to get a breath test. The breath test measures hydrogen, methane, and sometimes hydrogen sulfide gas levels exhaled in the breath that are byproducts of bacterial fermentation within the small and large intestine. While many breath test types exist, I typically I recommend a 3-hour Lactulose Breath Test, which can be ordered by your provider and is often covered by insurance.
Once diagnosed, treatments can be as simple as a two-week course of an antibiotic, or include the use of botanical antimicrobials or dietary changes. Specifically, limiting the consumption of high FODMAP (Fermentable Oligosaccharide, Disaccharide, Monosaccharides, and Polyol) rich foods for a time can be helpful.
Additionally, many folks will need support to prevent recurrence of the bacterial overgrowth, including use of supplements or medications to support intestinal motility, immune system function, and digestive secretions (think enzymes, acid, bile, etc!). While many patients feel better after just one round of treatment, inadequate treatment and/or relapse of the bacterial overgrowth can occur for some. My particular passion is to work with patients who have struggled to effectively treat their SIBO or experience frequent SIBO relapse.
Curious to learn more about SIBO?
For my take on more specific questions about SIBO, and the frequently confused, but separate condition - Intestinal Methanogen Overgrowth (IMO) - check out my personal website here (https://www.megantaylornd.com/common-sibo-questions ).
Looking for additional support?
If you suspect you or someone you know might have SIBO, feel free to schedule a visit with myself or one of our providers to review your testing and treatment options!
warmly,
Dr. Taylor
References
(1) Ghoshal UC, Shukla R, Ghoshal U. Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome: A Bridge between Functional Organic Dichotomy. Gut Liver. 2017 Mar 15;11(2):196-208. doi: 10.5009/gnl16126. PMID: 28274108; PMCID: PMC5347643.