Why does SIBO cause constipation?

Constipation in SIBO is primarily driven by methane gas, which is produced by specialized single-celled organisms called archaea—primarily Methanobrevibacter smithii. These archaea consume the hydrogen gas produced by neighboring bacteria and convert it into methane. Once present in the digestive tract, methane acts as a local neuromuscular inhibitor in the gut wall. This essentially paralyzes normal peristalsis, the wave-like muscular contractions that move food through the digestive system, significantly slowing down transit time. As a result of this delayed transit, the colon absorbs excess water from the stool, leading to dry, hard, and infrequent bowel movements. To understand how to manage this specific overgrowth, explore our comprehensive guide on [methane SIBO](/methane-sibo).

Disclaimer: This content is reviewed and fact-checked by Daryl Stubbs, Certified Holistic Nutritional Consultant (C.H.N.C), for educational purposes. It does not constitute medical advice or a doctor-patient relationship.