37. Candida and Histamine: Why Fungal Overgrowth Keeps Coming Back

In this episode of The Histamine Well Podcast, Joanne explores how candida, yeast, and fungal overgrowth can worsen histamine intolerance and trigger ongoing mast cell symptoms.

She explains how fungal-driven gut inflammation increases histamine production by activating mast cells, upregulating histidine decarboxylase (HDC), and reducing DAO enzyme activity — making it harder for the body to break histamine down.

You’ll learn why antifungals alone often fail, how gut “terrain” factors like low stomach acid, poor bile flow, digestive enzyme insufficiency, microbiome imbalance, mold exposure, and chronic stress allow fungal overgrowth to persist, and how SIBO and SIFO are connected through small intestinal pH imbalance.

If you struggle with histamine intolerance, sugar cravings, brain fog after carbs, bloating, or recurrent candida, this episode explains the deeper root causes — and why nervous system regulation is essential for long-term healing.

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Transcript

0:00

Hi, it's Joanne. What if the reason your Candida won't fully resolve isn't because you haven't found the right antifungal, but because the gut environment is still primed for it to thrive? So many people get stuck in the cycle of antifungals, strict diets, temporary relief, and then the rebound. Fungal overgrowth doesn't just randomly appear. It takes hold when the terrain of the gut has shifted. When the pH is off, the digestive secretions are compromised. The microbiome has thinned out. Immune signaling is dysregulated and the nervous system is stuck in survival mode. And yes, when that terrain changes, histamine often rises alongside it. In this episode, we are zooming out. We're looking at why candida overgrows in the first place and why restoring the ecosystem of the gut is far more powerful than simply trying to eradicate the fungus. 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 are 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 candida yeast and fungal overgrowth. Now essentially these are all in the same family. Fungus is the umbrella term. Yeast is a type of fungus, and candida is a specific type of yeast. But for the purpose of today's episode, I'm really talking about the broader fungal family. So fungus, yeast, and candida collectively. And what can happen when these organisms overgrow in the gut. So there are two really important points I wanna hone in on today. Firstly, fungal overgrowth absolutely increases histamine and secondly. And this is the part that's often missed. Fungal overgrowth doesn't just appear out of nowhere. It happens when the terrain of the gut has allowed it to overgrow. And when I talk about terrain, I'm talking about the internal environment in the gut. Things like pH of the digestive tract. Digestive secretion such as stomach acid and bile acids. The balance and diversity of the microbiome. Immune signaling in the gut. The integrity of the gut lining and even the nervous system input into digestion. So how does Candida fungal yeast overgrowth increase histamine? Well, it's actually really simple. Fungal overgrowth creates inflammation in the gut. When there's inflammation in the gut, an enzyme called the histidine decarboxylase enzyme becomes upregulated, and this enzyme converts histidine into histamine. And this process happens in multiple cell types throughout the body, including smooth muscle cells, epithelial cells, and gut cells. And at the same time, mast cells can become activated. And when mast cells become activated, they do what's called either differential release, which is slow release over time. Or they can degranulate, which causes a more of an acute, almost like an anaphylactic reaction. And often we see it in the skin. It will come out as hives. When all this inflammation is happening, the synthesis and secretion of the DAO enzyme that breaks down histamine is compromised. So you end up with increased histamine production, increased histamine release, and reduced histamine breakdown. And that's why fungal overgrowth and histamine symptoms so often go hand in hand. Now what we need to understand clinically is that taking antifungal herbs, if you have a chronic fungal issue, might actually be doing you a disservice. So herbal medicine is strong. It will reduce fungal load, but it will also reduce your beneficial bacteria. So it's going to compromise the terrain of the gut long term. And as I was saying, it's an unhealthy terrain in the gut that causes these fungal overgrowths in the first place. Now, saying that if you've had a great result from antifungal herbs, fantastic. But if you're finding that if you come off antifungal herbs and you keep rebounding, then that tells us that the terrain hasn't been addressed. So we need to stop bombing the gut with these herbs and ask why the overgrowth is happening in the first place. Firstly, let's talk about the pH in the digestive tract. The small intestine needs to be alkaline. When it becomes to acidic, you can develop sibo, small intestinal bacterial overgrowth. And at the same time, that acidic environment becomes a breeding ground for sifo, small intestinal fungal overgrowth. So SIBO and sifo often go hand in hand. So you can't directly test for sifo. But clinically, if someone has sibo, we can often extrapolate that sIFO may also be present. And someone with SIFO might have mouth rash, severe sugar cravings, intense carbohydrate cravings, crashing after eating sugar in particular. So like fatigue or extreme brain fog where they can't even string a sentence together. So when we treat sibo, we are actually often treating SIFO at the same time.'cause the herbal treatments for sibo, like Allicin, oregano and berberine are also broad spectrum antimicrobials and antifungals. And if you've done the SIBO diet, you know there's no fun, there's no sugar, no chocolate cake, no yeast, and very minimal fruit. So we are cleaning up a fungal overgrowth at the same time. 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, M-T-H-F-R, 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 and apply, visit joanne kennedy naturopathy com. One of the things that will really disrupt the pH of the gut is a lack of digestive enzymes. So when you chew your food, hydrochloric acid is released. And when that happens, a hormone message gets sent to the pancreas, and that allows the pancreatic juice to enter the small bowel, and that alkalizes the small intestine that allows your pancreatic enzymes to work properly in that alkaline environment. And as I was saying, that alkaline environment prevents this overgrowth of SIBO and SIFO. Now at the same time, a message gets sent to the gallbladder and whereby bile acids are released into the small bile. And bile helps digest fat. It's also antimicrobial antifungal. And it also acts as a laxative. It has many beneficial roles in keeping that terrain in the small bowel, in particular, in good health. And when this cascade is disrupted, the terrain shifts. And we get SIBO and sifo. So the other thing we need to really think about with terrain is the microbiome. So antibiotics can disrupt the pH of the gut. They can also eradicate a lot of your beneficial bacteria. And when beneficial bacteria are reduced, these opportunistic bacteria and fungi have more space to grow. So this is essentially called dysbiosis. And this will apply in the small intestine and the large intestine. So this reduced diversity equals more ecological space for fungal colonization. Another big driver here is mold. Mold can significantly disrupt the microbiome and mold illness goes hand in hand with fungal overgrowth. We see this all the time. On organic acids testing, we often see mold species such as aspergillus along with elevated yeast markers like aribanose and tartaric acid. Aribanose and tartaric acid are metabolite. The waste products of these fungal species. If candida hasn't shown up in a stool test for you. You strongly suspect some kind of fungal overgrowth and you can't test for cfo, then an organic acids can be really, really useful for you. It's very sensitive to these metabolites. If candida is there and it's not picking up in a stool test, then you will probably find it in an organic acid test. Now stress also significantly disrupts the microbiome. So stress alters, motility, digestive secretions, and immune signaling. So again, it's gonna shift this terrain into a more opportunistic environment for fungus to grow. We also need to think about immune signaling in the gut. Your gut is actually one of the largest immune organs in your body. You have immune cells sitting just underneath the gut lining, constantly assessing what's coming through. Food, bacteria, viruses, fungus. And deciding what is safe and what isn't. And when immune signaling is balanced, it keeps fungal organisms like candida under control. But when immune signaling becomes dysregulated due to stress, antibiotics, mold exposure, chronic inflammation, the immune system can become either underactive or overactive. If it's underactive, fungi aren't kept in check and can overgrow. If it's overactive, you get chronic inflammation, mast cell activation, and increased histamine release. So either way. The terrain shifts in favor of fungal persistence. Another critical part of the terrain is the integrity of the gut lining. The cells of the intestinal wall are held together by tight junctions. They're little seals that prevent unwanted particles slipping through. These tight junctions can be disrupted by antibiotics, mold, stress, dysbiosis, and for many people gluten. When they unravel, we develop intestinal hyperpermeability. Or more commonly known as leaky gut. So how does this make Candida worse? Well, when the gut lining becomes permeable, the immune system becomes constantly active. Chronic inflammation increases, that's gonna increase histamine. Secretory IGA can become depleted. Canida can adhere more easily to the damage lining. So instead of sitting harmlessly in the gut, it attracts colonizers and persists. And again, we have this environment of inflammation. Inflammation increases histamine, reduces DAO enzyme activity. Net result is way more histamine. Now, finally, I really need to talk about the nervous system. So your digestive system only works properly when you are in parasympathetic state. So rest and digest. If you are chronically stressed and stuck in fight and flight. Stomach acid can reduce pancreatic enzyme output can reduce bowel flow, can reduce gut motility, can slow down or become dysregulated. And when motility slows down, microbes including fungus, have more time to grow. And stress hormones also alter immune signaling. So your secretory iga can drop. Inflammation can rise. Mast cells, and these other gut cells are gonna become more reactive. So you can see we have this histamine storm. And this altered terrain, this environment now is opportunistic for candida to grow and to persist. So if you're constantly treating fungal overgrowth, but ignoring stress and nervous system regulation, you are missing a major piece because the nervous system is not separate from the gut, it's actually driving it. And we see this clinically all the time. Nervous system disruption leads to chronic gut issues. Chronic issues with the terrain, and then persistent issues like bacterial overgrowth, like fungal overgrowth. So if you've been struggling with chronic fungal infections, we are here to help. We see patients online globally. You can easily make an appointment via my website, joanne kennedy naturopathy.com. So 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. Leave a review and you can also share this episode with someone who could benefit. If you have any questions you'd like answered or have a topic you'd like me to discuss, please go to my website, joanne kennedy naturopathy.com, where you can provide us with that information. Until next time, take care and be well.