48. How Mould Mycotoxins Cause SIBO

In this episode of The Histamine Well Podcast, Joanne explores the hidden connection between mould mycotoxins and Small Intestinal Bacterial Overgrowth (SIBO) — and why so many people with chronic digestive symptoms may be missing the true root cause of their gut dysfunction.

If you’ve been struggling with bloating, reflux, constipation, diarrhea, histamine intolerance, food sensitivities, nausea, fatigue, or recurring SIBO that never fully resolves, this episode explains how mould exposure may be contributing to ongoing nervous system and digestive dysfunction.

Joanne breaks down the mechanisms behind mould-related gut issues, including how mycotoxins impact the vagus nerve, gut motility, stomach acid production, bile flow, pancreatic enzymes, inflammation, and the migrating motor complex. She also discusses why chronic SIBO cases are often difficult to treat when mould toxicity is not properly addressed.

In this episode, you’ll learn:

• Why mould illness and SIBO commonly occur together
• How poor vagal tone affects digestion and bacterial overgrowth
• The connection between mould, histamine intolerance, and mast cell activation
• Why low stomach acid and sluggish bile flow can worsen gut symptoms
• How chronic inflammation disrupts gut motility and digestive function
• Why antibiotics and herbal antimicrobials may not fully resolve SIBO
• The importance of mould testing in chronic gut health conditions

#SIBO #MouldIllness #HistamineIntolerance #GutHealth #Mycotoxins #MCAS #FunctionalMedicine #DigestiveHealth #MoldToxicity #VagusNerve

✨ Want more? Follow on Instagram, Facebook, and YouTube for updates and tips.

📘 New to this journey? Buy The Ultimate Bundle for Managing Histamine Intolerance—your step-by-step guide to manage your histamine intolerance effectively.

 🧪 Curious about your methylation status? Try our at-home Methylation Test! In just 15 minutes, discover if you're over-methylating or under-methylating and receive targeted supplement recommendations to help rebalance. Use code HISTAMINEWELL10 for 10% off.

🎓 Practitioner or student? Join the waitlist for the Histamine & Methylation Online Group Coaching Course starting early 2026!

📆 Work with us 1:1! Book a consultation and take your first step to real healing.

🎤 Have a topic suggestion? Submit it here!

Transcript

0:00

Hi, it's Joanne. If you've been struggling with SIBO, bloating, food intolerances, reflux, constipation, or diarrhea, you've probably been told that bacteria are the problem. And while that's often true, one of the biggest questions we need to ask is: why did those bacteria overgrow in the first place? What I see clinically time and time again is that many people with chronic gut issues have an underlying mold issue that has never been identified. Mold and mycotoxins can affect the nervous system, vagus nerve, stomach acid production, bile flow, digestive enzymes, and gut motility. All of the things that help keep the small intestine healthy and resistant to bacterial overgrowth. In this episode, I'm gonna walk you through the fascinating connection between mold illness and SIBO and explain why treating the gut alone is sometimes not enough to get people well. Welcome to the Histamine Well Podcast. Designed for practitioners and patients alike. This is your trusted source for insights on histamine intolerance, methylation, gut health, women's hormones, and much more. I'm Joanne Kennedy, your host, naturopath, author, and educator, passionate about breaking down complex science into clear, accessible knowledge. Whether you're a health professional or navigating your personal wellness journey, the Histamine Well Podcast bridges the gap between cutting-edge research and practical understanding to empower you with the tools to thrive. Hi, everyone. Welcome back to the Histamine Well. Today's episode is all about mold exposure and SIBO. Small intestinal bacterial overgrowth. And why clinically, I almost expect to see these two things show up together. Not every person with mold exposure develops SIBO, and not every person with SIBO has mold exposure. But there is a very strong clinical overlap between the two. And one of the biggest reasons for this is that mold and mycotoxins can profoundly affect the nervous system and digestive function. When digestion slows down, when bile flow becomes sluggish, when stomach acid and digestive enzymes decrease, and when the vagus nerve isn't functioning properly, the small intestine becomes a much easier place for bacteria to overgrow. So today, I want to walk you through the mechanisms behind this connection because I think it's massively under-recognized. So first of all, what is SIBO? SIBO stands for small intestinal bacterial overgrowth. Normally, the small intestine contains relatively low levels of bacteria compared to the large intestine. But in SIBO, bacteria start accumulating in the small intestine where they shouldn't be in large amounts. These bacteria ferment carbohydrates and fibers, producing gases like hydrogen, methane, and hydrogen sulfide. This can lead to symptoms such as bloating and abdominal distension, reflux, heartburn, belching, constipation or diarrhea, nausea, food intolerances, histamine symptoms, and fatigue. Importantly, SIBO is often not just a bacterial problem. It's frequently a motility and nervous system problem. So we need to understand that mold affects the nervous system. So one of the major ways mold contributes to SIBO is through its effect on the nervous system. Many mycotoxins are neurotoxic. They can affect the brain, autonomic nervous system, vagus nerve function, inflammation pathways, and mitochondrial function. This matters because digestion is heavily regulated by the nervous system. When the body is stuck in a chronic stress or inflammatory state, digestion becomes impaired. The body shifts resources away from digestion and into survival, and this is where we start seeing problems develop. Let's talk about the vagus nerve, because the vagus nerve is one of the major communication pathways between the brain and the gut. It helps regulate stomach acid production, digestive enzyme release, gallbladder contraction, gut motility, the migrating motor complex. And clinically, many people with mold illness appear to have impaired vagal tone. Which can show up as bloating and constipation, nausea and reflux, early fullness or food sitting heavily in the stomach, poor tolerance to supplements, heightened nervous system sensitivity. So when the digestive tract is impaired, it simply doesn't function optimally. A lot of these symptoms are SIBO symptoms. But what we need to understand, and I see this a lot, is that someone can have all the symptoms of SIBO And we think that the bacterial's overgrown in amounts that are gonna be picked up on test. But it comes back kind of borderline or negative. And so we're left with why is your digestion so compromised and why aren't you able to break down your food properly? And it can often be to poor vagal tone, which can be due to mold mycotoxins. So I just wanted to flag that. Sometimes we get quite a shock that the person's bacteria is not overgrown to a point where we need to treat the SIBO. But what we absolutely need to do is treat the mold. And get the mold out of the body and the inflammation down so that it can improve the vagal tone. So what else is going on? When there's poor vagal tone, we end up with reduced stomach acid. Okay, so stomach acid is incredibly important. It acts as one of the body's first defense mechanisms against unwanted microbes, helping to sterilize incoming food and prevent excessive bacterial survival. This is obviously gonna lead to SIBO. So when stomach acid is low, bacteria are more likely to survive and accumulate in the small intestine. So low stomach acid also impairs protein digestion, and it causes nutrient absorption, which can further weaken digestive function over time. We can often see that when someone has mold exposure, they do have massive issues with breaking down their food and their protein. They will end up with multiple food intolerances. They can end up with a lot of malabsorption of lot of nutrients. It's not just the fact that they might not be chewing their food and releasing the stomach acid adequately, or they've been taking proton pump inhibitors. They have zinc deficiency. Zinc increases hydrochloric acid. It's often not just the common things we see in clinic that are causing reduced stomach acid. We need to understand that if the vagus nerve is not working properly due to mold exposure. We can end up with reduced stomach acid. Now, like the stomach, the pancreas is also heavily influenced by nervous system signaling. So under the chronic stress and inflammatory states that we see in mold illness, pancreatic enzyme secretion may become impaired, and this means food isn't broken down properly. So it means carbohydrates, fats, and proteins remain poorly digested. They become fuel for bacterial fermentation in the small intestine. Leading to SIBO, the symptoms of SIBO, the gas, the bloating, the constipation, diarrhea, et cetera. The release of histamine as we commonly see. Before we go any further, I want to speak directly to the practitioners and students listening. If you're intrigued by histamine and methylation and eager to expand your knowledge in this fascinating area, we offer the Histamine and Methylation Online Group Coaching Course. The only program of its kind. It covers everything you need to know about histamine and methylation, providing both the theory and guidance you need to treat these issues effectively in clinical practice. We cover SIBO, hormonal imbalances, oxalates, MTHFR, the four pathways of methylation, including the folate pathway, methionine pathway, tetrahydrobiopterin pathway, and the all-important transsulfuration pathway, and much more. The program is delivered by detailed online webinars and handouts for you to keep, and for eight weeks, you'll meet with me for live coaching calls in a private community space with other practitioners from all over the world dealing with histamine and methylation issues in their patients every day. Together, we learn so much. To learn more and apply, visit joannekennedynaturopathy.com Now, the other thing that happens when there's poor vagal tone is that we can have sluggish bile. So bile is incredibly important for digestion. Obviously it emulsifies fats. It also supports detoxification. It regulates microbes in the small intestine. It has laxative properties. Issues with poor bile flow can definitely lead to SIBO. So what we see clinically is many people with mold illness will develop sluggish bile flow and poor gallbladder contraction. This can happen for several reasons. The nervous system dysfunction, vagal impairment inflammation, reduced phosphatidylcholine production, or toxin burden affecting the liver and biliary system. So when bile flow slows down, we lose one of the gut's natural antimicrobial defense mechanisms, creating a much more favorable environment for bacterial overgrowth. Again, SIBO. So guys, we can see that it's like no doubt. I mean, people always have SIBO if they've had mold exposure. Like 90% of the time. And becomes a bit of a clinical dilemma because not only do they have SIBO, they often have issues with sulfur intolerance, oxalates. They have multiple, multiple food intolerances. So where do you start? We often yet don't actually start with treating SIBO. We start with doing a workup with mold and doing mold binding. We often need to deal with the oxalate problem. We need to deal with the nervous system. But I just wanted to do this episode because it's kinda like a given that these people are gonna have SIBO. So what else is happening? We can also end up with slower gut motility and issues with the migrating motor complex. So this is probably the biggest mechanism linking mold and SIBO. So the small intestine has cleansing waves called the migrating motor complex, which helps sweep bacteria through the digestive tract between meals. And this system is heavily regulated by the nervous system. When the body is chronically inflamed from mold mycotoxins or stuck in survival mode from stress, motility can slow down significantly. Food sits longer. Bacteria sits longer. Fermentation increases, and over time, this creates the perfect environment for SIBO. What we also see with mold is that it just causes so much inflammation in the gut. And when we see inflammation, we see increased intestinal permeability, increased mast cell activation, increased histamine release, immune dysregulation, oxidative stress. All of this can further disrupt digestion and motility. So inflammation itself can impair vagal signaling and nervous system regulating, creating a really vicious cycle between digestion progressively worsening over time. And I think this is when people are misdiagnosed with the root cause of their gut issue, and they're given antibiotic after antibiotic or herbal medicine after herbal medicine. Herbs are really strong, guys. We've gotta remember that, you know, things like berberine, they're super strong. And people can end up with like reducing your beneficial bacteria even more when beneficial bacteria really help regulate immune function. So this is what we see clinically a lot. It's not misdiagnosed. They're just often the mold is not picked up. And they're treated for like parasites that are not really a problem. Or if they are treated for mold, they're bombarded with antibiotics and then they end up with a lot of immune dysregulation in their gut. And they still have the problem because mold was the driver in the first place. So for practitioners listening, if you're not already doing a mold workup for your SIBO patients or even your gut patients, like I really think you're doing a disservice. And we were not really taught to do that at college, but I see it time and time and time again, and so do the girls that do my course, that mold is such a driver of gut dysfunction and SIBO. You know, it completely disrupts the entire gut terrain. So if you've got SIBO cases that are a bit stuck and chronic and you're not sure why you can't get on top of the SIBO, then I encourage you to do a mold mycotoxins test. For patients listening, we absolutely offer mold mycotoxins testing as part of our workup for chronic gut issues. So if you're interested in working with us, we see patients online globally via Zoom. You can easily book an appointment to see us via my website, joannekennedynaturopathy.com. Thank you for joining me. I hope you found this episode beneficial. Be sure to subscribe to The Histamine Well so you don't miss an episode. If this podcast has supported you, one of the most impactful ways to help us reach more people is to leave a review on Apple or Spotify. Take a quick screenshot and email it to us at info@joannekennedy.com.au and as a thank you gift, we will send you a copy of my histamine intolerance e-book. Until next time, take care and be well.