These three terms appear constantly in gut health conversations. They're often confused, frequently overlap, and are sometimes used interchangeably — incorrectly.
IBS is a functional diagnosis — meaning it describes a pattern of symptoms (bloating, cramping, altered bowel habits) without a specific structural cause identified. It's a label that tells you what you experience, not why. For many people, IBS is a starting point for investigation rather than a final answer.
SIBO occurs when bacteria that should be in the large intestine migrate into and proliferate in the small intestine. The small intestine is not designed to host large bacterial colonies — when it does, fermentation of food in the wrong place causes significant bloating, gas, pain, and altered motility. Research suggests SIBO is present in a significant proportion of people diagnosed with IBS.
The gut lining is a single cell layer thick — a remarkable barrier that selectively allows nutrients through while keeping pathogens and undigested particles out. When this barrier is compromised — through dysbiosis, chronic stress, alcohol, NSAIDs, or poor diet — it becomes more permeable, triggering immune responses, systemic inflammation, and symptoms that extend far beyond the gut.
SIBO can cause or worsen intestinal permeability. Intestinal permeability can drive immune dysregulation that makes IBS symptoms worse. IBS is often the presenting complaint that, when investigated properly, reveals SIBO or permeability as contributing drivers.
This is why treating IBS symptomatically — without asking why — so often produces temporary relief at best. The root cause remains.
Work with Michaela
A free 20-minute discovery call is the best place to start. We'll talk through your symptoms and whether working together is the right fit.
Book a Free Discovery Call