How the thyroid affects the gut
Thyroid hormones help regulate the speed of the entire digestive tract. When levels are low, gut transit slows, the migrating motor complex weakens and stomach acid production can drop. All three make it easier for bacteria to settle in the small intestine.
What research shows
Several studies have found a higher prevalence of SIBO in people with hypothyroidism, including Hashimoto's thyroiditis, compared with healthy controls. The relationship also seems to work both ways: gut inflammation and absorption problems may in turn affect thyroid function and the uptake of thyroid medication.
Signs to watch for
- Persistent constipation or methane-dominant breath test
- Fatigue, feeling cold, dry skin, hair loss
- Bloating that doesn't respond to dietary changes
- SIBO that keeps coming back
What this means for your pathway
If your SIBO keeps returning, it is worth having your thyroid function checked by your physician. Optimising thyroid function is not something we do — that remains with your doctor — but taking it into account is essential for lasting recovery and relapse prevention.
This article is for general information and does not replace medical advice. Medical decisions, medication and prescriptions always remain with your physician.
Thyroid issues and gut complaints?
A breath test clarifies whether SIBO plays a role.