# SIBO Symptoms and Treatment: Why Fibre Makes It Worse > Why adding more fibre triggers bloating, greasy stools, and gut inflammation in SIBO — and what to do when stopping the fibre doesn't fix it. - Source: https://gutfix.ai/blog/sibo-symptoms-and-treatment - Author: Kieran, GutFix co-founder (https://gutfix.ai/about) - Published: 2026-06-25 - Category: SIBO, Bile Flow - Reading time: 6 min You added more fibre because trials show it "improves gut health". You've been told it's essential. But in an overgrown gut, fibre starts three cascades simultaneously. And one of them keeps running even after you take the fibre away. ## Key takeaways - The bloating AND the inflammation AND the greasy stools all traced back to one group of bacteria processing fibre through BSH. - The cycle is now self-sustaining. It doesn't need fibre anymore. - Same input. Completely different outcome. The difference was never the fibre. It was the state of the system processing it. ## Why Does Adding More Fibre Make SIBO Symptoms Worse? You added more fibre because trials show it "improves gut health". You've been told it's essential. More flax. More chia. More oats. Your bloating got worse. Your stools got stickier despite eating less fat? So you stopped and still feel worse than when you began. In a healthy gut fibre does exactly what it's supposed to. Feeds beneficial bacteria, produces butyrate, improves stool quality. But in an overgrown gut, fibre starts three cascades simultaneously. And one of them keeps running even after you take the fibre away. ## What Is the First Cascade Fibre Triggers in an Overgrown Gut? The first is the one you feel fastest: Gas. Bacteria in your small intestine ferment fibre into hydrogen. That hydrogen feeds archaea that convert it into methane. Methane directly slows gut transit by 59%. Slower transit means food sits longer. More sitting means more fermentation. More fermentation means more hydrogen. More hydrogen means more methane. That cycle doesn't stop after one meal. It accelerates through the day. The bloating that's mild in the morning and unbearable by dinner, the distension that makes your waistband dig in by mid-afternoon. Fibre is the culprit. ## What Does Fibre Do to Bile Acids in SIBO? The second is what happens to your bile. The same bacteria fermenting your fibre are simultaneously using BSH enzymes to strip your [bile acids](https://gutfix.ai/blog/what-does-having-sibo-feel-like) apart. Nearly 60% of bile function can be lost this way. Less functional bile means fats pass through undigested. Stools get stickier, greasier, paler. Overgrowths persist as your naturally antimicrobial bile is broken. But the bile isn't just being destroyed. It's being converted into something actively harmful. A 2022 study in Nature showed that bacteria modify bile acids into a compound that triggers an immune response in your gut wall. IL-33 activates immune cells called ILC2s and causes type 2 inflammation resembling an allergic reaction inside your intestine. The researchers proved it was specifically the bacterial enzyme doing this. When they knocked BSH out of a single bacterial species the fibre caused next to zero inflammation. Same fibre. Same gut. Remove one bacterial enzyme and the inflammation vanishes. The fibre isn't the issue but what the bacteria does with it is. The bloating AND the inflammation AND the greasy stools all traced back to one group of bacteria processing fibre through BSH. Until the [microbiome](https://gutfix.ai/blog/what-are-the-triggers-for-sibo) is balanced, both fats AND carbs/fibre are going to cause issues. ## Why Don't SIBO Symptoms Improve After Cutting Out Fibre? How come once you tried cutting it out things didn't get any better? A third group of bacteria converts hydrogen into hydrogen sulphide. H2S doesn't just smell like rotten eggs. It directly damages your [gut lining](https://gutfix.ai/blog/how-do-you-tell-if-you-have-sibo-3) cells. Combine this with the toxic bile acids and plenty of damage is being done. Those cells have mitochondria that consume oxygen and keep the inside of your intestine almost completely airless. That airless environment is what prevents gram-negative endotoxin producers from taking over. It's what allows beneficial bacteria to dominate. It's what keeps antimicrobial peptide production running. When H2S damages those cells they stop consuming oxygen properly. Oxygen leaks into the lumen. Gram-negatives expand. They are made of more endotoxin. More endotoxin damages the lining further. Less antimicrobial peptide production. Less defense against the bacteria causing the damage. More oxygen. More gram-negatives. The cycle is now self-sustaining. It doesn't need fibre anymore. This is why you stopped the flax and chia weeks ago and your symptoms are the same or worse. The fibre lit the match. The fire is feeding itself. The environmental damage created conditions where the bacteria driving the damage now have a permanent growth advantage regardless of what you eat. ## What Does Fixing the SIBO Environment Actually Look Like? Two people add the same fibre to their diet. One gets better digestion. The other triggers a cascade that outlasts the fibre itself. Same input. Completely different outcome. The difference was never the fibre. It was the state of the system processing it. Fixing it means addressing the environment the fibre exposed, not just removing the fibre. Zinc L-Carnosine to repair the lining. PQQ and CoQ10 to restore mitochondrial oxygen consumption. Butyrate to fuel both the lining cells and mucus production. Baicalein to shut down the BSH enzymes degrading bile. Boswellia to lower the inflammation and thicken the mucus layer that protects the lining from further damage. Remove the fibre and the input stops. Fix the environment and the cycle breaks. ## Frequently asked questions ### Why does fibre make bloating worse in SIBO? Bacteria in your small intestine ferment fibre into hydrogen. That hydrogen feeds archaea that convert it into methane. Methane directly slows gut transit by 59%. Slower transit means food sits longer. More sitting means more fermentation. More fermentation means more hydrogen. More hydrogen means more methane. That cycle doesn't stop after one meal. It accelerates through the day. ### Why are my stools sticky and greasy after eating fibre? The same bacteria fermenting your fibre are simultaneously using BSH enzymes to strip your bile acids apart. Nearly 60% of bile function can be lost this way. Less functional bile means fats pass through undigested. Stools get stickier, greasier, paler. Overgrowths persist as your naturally antimicrobial bile is broken. ### Why do my symptoms stay the same even after I stopped eating fibre? The fibre lit the match. The fire is feeding itself. The environmental damage created conditions where the bacteria driving the damage now have a permanent growth advantage regardless of what you eat. This is why you stopped the flax and chia weeks ago and your symptoms are the same or worse. ### What is hydrogen sulphide doing to my gut? H2S doesn't just smell like rotten eggs. It directly damages your gut lining cells. Combine this with the toxic bile acids and plenty of damage is being done. Those cells have mitochondria that consume oxygen and keep the inside of your intestine almost completely airless. When H2S damages those cells they stop consuming oxygen properly. Oxygen leaks into the lumen. Gram-negatives expand. ### What does treating SIBO involve beyond removing fibre? Fixing it means addressing the environment the fibre exposed, not just removing the fibre. Zinc L-Carnosine to repair the lining. PQQ and CoQ10 to restore mitochondrial oxygen consumption. Butyrate to fuel both the lining cells and mucus production. Baicalein to shut down the BSH enzymes degrading bile. Boswellia to lower the inflammation and thicken the mucus layer that protects the lining from further damage. --- GutFix is an educational gut-health system, not medical advice, and never a reason to change anything a clinician has prescribed. - Get GutFix: https://gutfix.ai/get-gutfix - More articles: https://gutfix.ai/blog · index for LLMs: https://gutfix.ai/llms.txt · every article in one file: https://gutfix.ai/llms-full.txt