What other conditions are associated with an increased risk of SIBO?

Although SIBO hasn’t been identified as a definitive cause or consequence of any other disease, it is associated with a number of conditions that create an abnormal intestinal environment, which could include:

• A less acidic (more hospitable) small intestine
• Slower (more accessible) transit of food through the GI tract
• Abnormal muscular contractions that push contents (and microbes) backward, from the large to the small intestine
• Reduced immune activity that would normally regulate microbial growth

It is thought that these factors create a nutrient-rich environment that lacks the normal mechanisms for controlling microbial growth, and SIBO develops as a result.^[1][2]

Functional dyspepsia (commonly known as indigestion), IBS, IBD, diabetes (types 1 and 2), dysregulated gut motility (food moving more slowly through the intestines due to abnormal muscular contractions), chronic pancreatitis, chronic liver disease, Parkinson’s disease, and systemic sclerosis (an autoimmune disorder) are all associated with greater odds of a positive SIBO diagnosis. Limited evidence also suggests that females with IBS may be more likely to have SIBO compared with males who have IBS.^{[3][4][1][5][6][7][2][8][9][10]}

A history of GI surgery (such as gastric bypass or resectioning of the intestines), the use of acid-reducing proton-pump inhibitors (PPIs), and smoking are also associated with a greater likelihood of having SIBO.^[5][1][11]

Though celiac disease isn’t linked to an increased chance of having SIBO, one analysis observed higher rates of SIBO in people with celiac disease who were unresponsive to a gluten-free diet compared with healthy controls. However, most of the analyses detected inconsistencies and issues with the quality of studies used to determine the prevalence of SIBO in these conditions.^[12]