SIBO Root Causes
Why Do You Keep Getting SIBO? Find Your Root Cause
SIBO is rarely the whole story. It is almost always downstream of something else — impaired motility, structural damage, medication effects, or immune dysfunction. Until you identify and address the underlying cause, SIBO will keep coming back. Take our diagnostic quiz or explore all 15 root causes below.
Find Your SIBO Root Cause
Answer 18 questions about your symptoms, medical history, and risk factors. This assessment evaluates your pattern against 15 known root causes of SIBO.
Explore All 15 Root Causes
Each root cause has a dedicated section with detailed articles, diagnostic guides, and specific testing recommendations.
Post-Infectious
Up to 10 percent of food poisoning episodes lead to chronic gut problems. The bacterial toxin CdtB triggers autoantibodies against vinculin, a protein essential for the migrating motor complex. This immune-mediated nerve damage impairs gut motility and creates conditions for bacterial overgrowth that keeps returning.
MMC/Motility
The migrating motor complex sweeps bacteria and debris from the small intestine every 90 to 120 minutes during fasting. When it is impaired, bacteria accumulate and SIBO develops. MMC dysfunction is the single most common mechanism behind recurring SIBO.
Gastroparesis
Gastroparesis affects up to 5 percent of the population and creates a backup effect that promotes bacterial overgrowth. Nausea, early fullness, and food sitting in the stomach for hours are hallmark symptoms.
Hypothyroid
Thyroid hormone is essential for gut motility. When thyroid function is low, the entire digestive tract slows down, creating ideal conditions for bacterial overgrowth.
ICV Dysfunction
The ileocecal valve prevents bacteria-dense colonic contents from flowing backward into the small intestine. When it fails, SIBO returns rapidly after every treatment.
Adhesions
Adhesions form in 93 to 100 percent of patients after abdominal surgery. These fibrous bands create kinks and partial obstructions where bacteria accumulate.
Low Stomach Acid
Hydrochloric acid kills the majority of bacteria you ingest. When acid production is insufficient, bacteria survive the stomach and colonize the small intestine.
EPI
When the pancreas does not produce enough digestive enzymes, undigested food becomes fuel for bacterial overgrowth.
Bile Acid
Bile acids serve two critical functions: fat digestion and antimicrobial defense. When bile flow is reduced, both digestion and bacterial defense are compromised.
Immune
Secretory IgA is the immune system's frontline defense against bacterial overgrowth. When immunoglobulins are deficient, bacteria proliferate unchecked.
Medications
Several widely prescribed medication classes directly increase SIBO risk by impairing stomach acid, gut motility, or immune function.
Vagus Nerve
The vagus nerve is the master controller of gut motility. Damage from surgery, trauma, chronic stress, or infection can permanently impair vagal signaling, leading to chronic SIBO.
Connective Tissue
Ehlers-Danlos syndrome, scleroderma, and other connective tissue disorders directly affect gut structural integrity and motility. GI dysfunction is present in up to 75 percent of EDS patients.
Stress/Lifestyle
Chronic stress shifts the nervous system into sympathetic dominance, directly impairing gut motility and immune function. These modifiable factors often compound other root causes.
H2S SIBO
Hydrogen sulfide SIBO is produced by sulfate-reducing bacteria and was undetectable on older two-gas breath tests. The Trio-Smart test now measures all three gases.
How We Write This Section
Every article in this section is written by our team and reviewed against peer-reviewed research. We cite sources, flag what is still hypothesis-level, and update articles when the science changes. If something here is wrong, we want to know.
Medical Disclaimer: The content in this section is for informational and educational purposes only. It does not constitute medical advice, diagnosis, or treatment. Always consult with a qualified healthcare professional before making changes to your health regimen. GLP1Gut is a tracking tool, not a medical device.