IBS 101: What is SIBO?

Published on Tuesday, January 11, 2022 by Allison Koch

Is it IBS or SIBO…Or Both?

Small Intestinal Bacterial Overgrowth (SIBO) has been steadily making its way into the conversation relative to IBS because the symptoms are similar: abdominal pain, abdominal discomfort, flatulence (gas), bloating, and loose stools. With SIBO, there is an increase in the number and type of bacteria in the upper gastrointestinal tract (GI tract).

In our bodies, we have many mechanisms that prevent bacterial overgrowth. With SIBO, there can be a disorder or dysfunction of one or more of those defense mechanisms that are preventing the bacterial overgrowth in the body, or even something more complex such as an underlying disease further complicating the overgrowth (such as chronic pancreatitis). This can cause a cyclic effect.

Some Factors that Increase your Risk of SIBO

Previous gastrointestinal/abdominal surgery
Gastrointestinal fistula
Medical history of diabetes, Crohn’s disease, diverticulosis of the small intestine, and gastrointestinal cancer (radiation therapy to the abdomen can also increase the risk of SIBO)
Structural defects in- and/or injury to the small intestine
Hypochlorhydria (low stomach acid) through H. Pylori infection, gastric bypass surgery, or extended use of proton-pump inhibitor (PPI) medications or antacids.
Overuse of abuse of narcotics and antibiotics.

Many research studies have suggested that between 31-80% of IBS sufferers also have SIBO. The gold standard for diagnosis of SIBO is quantitative jejunal aspirate and culture, which is an investigation completed via an EGD. This is an invasive, costly procedure that does not always detect bacteria overgrowth because the overgrowth itself can be patchy. However, glucose hydrogen breath tests are popular because they are noninvasive, but also vary in their specificity.

Nutrition Interventions with SIBO

As with any other health condition, several diets have been created to assist with symptom management of SIBO, but there is not enough research to say that one is “better” than the other. What we do know is that the American College of Gastroenterology has made some recommendations very similar to what IBS sufferers already hear with the Low-FODMAP dietary pattern:

Reduce fermentable food intake

This will likely include low fiber
Avoid inulin (a prebiotic)

Avoid sugar alcohols

Including fermentable sweeteners

With 3 out of 4 people who suffer from IBS reporting relief from symptoms associated with their IBS on the Low-FODMAP diet and between 31-80% of SIBO sufferers also reporting having IBS, there is still not enough research out there to say that the Low-FODMAP diet is the saving grace for all IBS sufferers, but it could be a great place to start with the help of a Registered Dietitian. Even if this does not work for you, nutrition is very personal and individualized, which is why a tailored plan is just as important as any other part of your healthcare needs if you are suffering.

Want a deeper dive into SIBO? Check out the American College of Gastroenterology’s Clinical Guidelines for SIBO.