Why Your IBS Might Actually Be SIBO

IBS is one of the most common diagnoses handed out in gastroenterology offices. It is also one of the least investigated. Here is what typically happens: you describe your symptoms — bloating, gas, alternating constipation and diarrhea, cramping that seems to have no predictable pattern — and you are told you have Irritable Bowel Syndrome. You are given a list of foods to avoid, maybe a prescription for an antispasmodic, and sent home. The diagnosis is real. The investigation stops there. What most people are never told is that IBS is a symptom cluster, not a root cause. It describes what your gut is doing. It does not explain why. One of the most commonly missed drivers of IBS-type symptoms is SIBO — Small Intestinal Bacterial Overgrowth. SIBO occurs when bacteria that belong in your large intestine migrate into the small intestine, where they ferment carbohydrates before your body can absorb them. The result is exactly what you would expect: gas, bloating, distension, and unpredictable bowel changes. It can look identical to IBS on paper. The difference is that SIBO is diagnosable and treatable. A lactulose or glucose breath test can confirm bacterial overgrowth in the small intestine. Once confirmed, there is a clear clinical path forward — whether that involves targeted antimicrobials, herbal protocols, motility support, or dietary modification during treatment. The reason SIBO gets missed is that standard GI workups do not include breath testing. If your doctor is not looking for it, they will not find it. This is why functional nutrition investigation matters. We do not start with a diagnosis. We start with a question: what is actually driving this? The answer changes everything about how we approach your care. If you have been living with IBS for years without resolution, it is worth asking whether the right questions have been asked. [Book a free strategy call](https://jackiehackett.com/vsl) to talk through what a root-cause investigation would look like for you.