Is There A Link Between SIBO And IBS?

At present the relationship between SIBO and IBS is not completely clear, but some medical studies show a connection in symptoms in people suffering from Small Intestinal Bacteria Overgrowth (SIBO) and Irritable Bowel Syndrome (IBS).

What is SIBO?

Turn on the television and you will see a commercial for probiotics or a yogurt product that promotes the growth of “good” bacteria. This bacteria is also called gut flora or microbiota and resides mostly in the large intestine.  Normally there is very little bacteria present in the small intestine, some bacteria can be found where the small intestine meets the large intestine. There are no bacteria in the stomach or the connecting part of the small intestine due to the presence of stomach acid. When someone suffer from SIBO it means that he or she hosts a lot of the wrong type of bacteria in the small intestine. A high amount of SIBO cases are caused by the wrong type of bacteria being present or bacteria from the large intestine migrating into the small intestine.  There are several gastrointestinal problems that SIBO can cause, including malabsorption of food causing vitamins and mineral deficiency, the small intestine also a condition that allows too much water to absorb into the small intestine resulting in the fermentation of the bacteria present or the growth of new bad bacteria.

The good bacteria in our gut has a very important role in our overall health including protecting against infection caused by bad bacteria, improve muscular activity of the small intestine and helping our overall immune system.

Causes of SIBO

For proper intestinal health, you need to keep your “good” bacteria in proper balance. Normal levels are accomplished by having normal levels of stomach acid; proper motility in your intestines (ability to move food and waste through properly); normal mucosa (lining of the intestines); properly functioning pancreas and gall bladder and normal valves.

The cause of SIBO is actually quite complex due to it being the result of other medical conditions affecting the bacteria balance within the digestive system. Some of the causes may include prior bowel surgery, multiple courses of antibiotics, low stomach acids etc.

There is a breath test that physicians may do that measure hydrogen and methane output. These tests produce many false positives, but it is still the only reliable way.

Symptoms of SIBO

Recognizing the symptoms of SIBO is often difficult for sufferers and for their doctors, as the symptoms can mirror other digestive issues, like the Irritable Bowel Syndrome.

Patients should look for: 

  • Gas/bloating, especially after eating
  • Stomach cramps
  • Diarrhea/Constipation or both
  • Fatigue
  • Nausea
  • Nutrient deficiencies and their associated symptoms
  • Joint pain

Diagnosing SIBO

SIBO is largely under-diagnosed in patients due to doctors not being aware of the condition’s prevalence in people. In addition, many people fail to seek treatment when suffering from symptoms related to SIBO. 

It is difficult to diagnose SIBO, but there are some tests which can help:

Hydrogen Breath Test: Can check for SIBO, H-Pylori Infection and carbohydrate malabsorption.

Patients are usually asked to be on a special diet for a day and just before the test they need to drink a sugar solution of glucose or lactulose.

Are SIBO and IBS related?

There is no more denying the similarities of symptoms between SIBO and IBS and studies estimate that a big percentage of people diagnosed with IBS also have SIBO. Small bowel dysmotility has been suggested as the predisposing factor. Because of the noted similarities, doctors often are treating patients with IBS as if they had SIBO without even testing for it. 

Curing SIBO

In order to properly treat SIBO, the underlying cause must be addressed first. As an example, if the patient has SIBO because of celiac disease, no treatment will help with SIBO unless the patient first follows a strict gluten-free diet.

Usually antibiotics are prescribed as a treatment for SIBO and although initially effective the symptoms often returns shortly after having finished the course of antibiotics. Probiotics have also been found to help with SIBO.

When trying to understand the possible cause of SIBO  there are several therapies which could also help: 

  • Diet, such as the low FODMAP diet, which reduces the carbohydrates as they are the main source of food of bad bacteria 
  • Motility agents
  • Digestive Enzymes
  • Exercise
  • Hypnotherapy
  • Meditation
  • Stress Reduction

Low FODMAP Diet and SIBO

Fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) are molecule-sized carbohydrates that, in some individuals, are not processed properly by their digestive system. These molecules ferment in the intestines causing those nasty symptoms. A diet low in FODMAPs has been shown to relieve the symptoms of both IBS and SIBO.

Together with the diet, which should be followed with the help of a dietitian, exercise, stress relief activities and use of specific probiotics can also help.


Quigley, Eamonn M. M., MD. Gut Bacteria and IBS. International Foundation for Functional Gastrointestinal Disorders. Web Accessed May 14-17, 2015.

Burkhart, Amy, M.D., R.D. SIBO, Gluten and IBS: What Is The Connection? Web Accessed May 14-17, 2015.

Siebecker , Dr Allison. Dietary Treatments. SIBO-Small Intestinal Bacteria Overgrowth. Web Accessed May 14- Web Accessed May 14-17, 2015.




About Larah

I have been suffering from Irritable Bowel Syndrome for many years, but it took a longtime to get a diagnosis, since then I have been following a low FODMAP diet, which has changed my life for the better. This is my story and experience with IBS and the low FODMAP diet.

3 comments on “Is There A Link Between SIBO And IBS?

  1. The importance of the type of bacteria in the gut and our overall health, reaction to certain foods (or even ones that are most likely to make us fat, or thin for that matter) is massively under-rated. I recommend a book called the diet myth by tim spector. This does not include any recipes or anything like that, but explains and gives reasonable and feasible arguments that the diets we are encouraged to follow are not as simple as just “low fat” etc… My issue with probiotics in general is (a) how you cannot rely on a particular product having the number of bacteria they claim and (b) actually getting those good bacteria into the lower intestine; past the stomach acid. The best products I find are the freeze dried ones, that come refrigerated and must remain as such. But having said that, and increasing as I have my sugar intake on the fodmap – sugar restricts the bacterial growth giving the probiotic less chance of taking hold. Our overuse of antibiotics does not help matters, but that is most certainly another argument for another day. Great article though!!

    • Thank you for reading and posting a comment Patrik, I dare you to start the 21 days of real low FODMAP food with me on the 1st of June ;-D

Comments are closed.