Adapted from episode 140 of The Perfect Stool podcast and edited for readability with Lindsey Parsons, EdD.
The Impact of Mold and Mycotoxins on the Gut Microbiome
When should I suspect mold toxicity or mycotoxin illness?
While I feel most comfortable in my niche area of gut health and autoimmunity, I have found myself quite often recently working with clients who didn’t realize that underneath their gut health issues was mycotoxin illness. The way I usually discover this is that either the gut issues just aren’t getting better, or they can hardly tolerate any supplements that impact gut issues, or in our initial intake they mention a potential past or current mold exposure. So we do testing for mycotoxins and sure enough, they come out positive for some, or in some cases, nearly all tested mycotoxins.
I looked at these clients and I was trying to find common symptoms with all of them, and the one that I have noticed for all of them, anecdotally of course, is anxiety. While they might mention it on our first call, this manifests itself pretty clearly to me in frequent emails to ask numerous questions, worries about how they will follow my recommendations, clarifications of how to precisely follow instructions, and the general need for reassurance that they’re doing the right thing. Some had constipation, which in several cases was also caused by diagnosed methanogen overgrowths, almost all had food sensitivities, usually including histamine reactions, some worse than others.
And for the ones who I suspect had genetic susceptibilities affecting detoxification or immune regulation which would make them particularly vulnerable to mycotoxin illness, symptoms often appear across multiple body systems, from the skin, to headaches, brain fog, breathing issues, hair loss and autoimmune diseases. And many showed obvious signs of yeast, like a white coating on their tongue or recurrent yeast infections. But all that is just my anecdotal experience. Let’s delve into the official information on all of this.
What are mold and mycotoxins?
Mold grows on organic substances and decomposes them to absorb their nutrients. It grows optimally in moist environments with organic material to feed on, with humidity levels exceeding 70%.
Mold and fungi release mycotoxins as a defense mechanism against predators. These mycotoxins may help weaken host defenses in animals and plants, though their primary role is often competitive — inhibiting other microbes, which indirectly helps the mold in colonizing. Fluctuating environmental conditions (temperature, moisture, UV exposure and nutrient scarcity) can also trigger the release of mycotoxins. Finally, some mycotoxins are produced naturally as a result of environmental stress, namely oxidative stress caused by environmental factors, including fluctuating oxygen levels, nutrient scarcity or chemical exposures. As a result, harmful gases, such as superoxide radicals, hydrogen peroxide and hydroxyl radicals are formed within fungal cells under stress conditions. Highly fluctuating oxygenation levels, like rapidly moving from low to high oxygen levels (i.e a fungus being buried underground to sprouting out of the ground) can also cause the release of these harmful gases.
Where is mold commonly found?
Common sources of mold exposure include water-damaged buildings, especially those affected by flooding or leaks, as well as poorly-ventilated, moisture-prone areas like bathrooms, laundry rooms, attics and crawl spaces. Mold can also grow inside plumbing systems, air conditioning units, and older carpets and appliances, particularly when they trap moisture. In humid climates, mold is more likely to thrive both indoors and on stored foods such as grains, coffee, cocoa, dried beans, sesame seeds, cheese, yogurt, malt, beer, nuts, fruit, dried fruit, and spices, where improper storage can encourage contamination.
Is everyone affected by mold?
Mold spores are found ubiquitously in the air we breathe. However, most people do not experience adverse effects due to several mitigating factors. First, our immune system is capable of clearing low level mold exposure. Also, neutrophils in the lungs kill germinating mold spores asymptomatically. However, for people with compromised immune systems or lung function, they may be at a higher risk of developing adverse health effects after exposure to mold. Furthermore, only a few species of mold are harmful to humans. The overwhelming majority of mold species are not harmful to humans, which are called saprophytic molds, which feed on dead organic matter and typically do not infect humans, and many more don’t even produce mycotoxins.
Of those that do produce mycotoxins, only a handful are pathogenic. Finally, genetics play a large role in determining whether or not a person is highly susceptible to mold toxicity. Genes involved in immune regulation, detoxification pathways and inflammatory cytokine production can influence how someone responds to mold exposure. Specific genes like HLA-DR have been implicated in mold illness susceptibility, particularly in people with Chronic Inflammatory Response Syndrome (CIRS). People with certain cytokine gene variants may be more prone to chronic inflammation after mold exposure.
Do mycotoxins affect the gut microbiome?
Mycotoxins can significantly disrupt the gut microbiome, leading to dysbiosis, or microbial imbalance. Research shows that mycotoxins reduce beneficial bacteria such as Lactobacillus and Bifidobacterium, while promoting the overgrowth of inflammatory species, particularly from the Proteobacteria phylum. Mycotoxins have been shown to damage the epithelial lining of the gut, increasing gut permeability. Increased gut permeability allows undigested food particles, toxins and microbes to enter the bloodstream, putting stress on the immune system and, over time, can dysregulate immune responses. This microbial imbalance and leaky gut is at the root of food sensitivities and chronic inflammation, creating a cycle of ongoing gut damage and immune activation, which may manifest as brain fog, joint pain, skin issues and autoimmune flares.
Mycotoxins also impair the gut microbiome’s detoxification capacity, further weakening the body’s ability to clear toxins and maintain gut barrier integrity. These toxins can further alter the gut ecosystem, amplifying inflammation and weakening the gut lining. However, research suggests that prebiotics and probiotics may help restore microbial balance and enhance the gut’s ability to metabolize and neutralize mold-related toxins before they trigger further disruption. Supporting a diverse and resilient microbiome may be one of the most effective strategies for protecting gut health in the face of mold and mycotoxin exposure.
Can mycotoxins lead to SIFO or candida?
The modulation of the gut microbiota by mycotoxins can also lead to SIFO (Small Intestine Fungal Overgrowth) or Candida overgrowth. While candida is a normal resident of the gut, when it overgrows it can extend beyond the gut, through hyphae, which are branching filament-like structures that can penetrate gut tissue, contributing to intestinal permeability. Systemic candidiasis can manifest as bloating, sugar cravings, sinus congestion, skin rashes, brain fog or fatigue, and may also be evidenced by yeast infections, fungal nail infections or thrush, which can be seen as a white coating on the tongue.
How do mycotoxins affect your immune function?
The inflammation and immune dysregulation associated with mycotoxins may contribute to the reactivation of chronic infections like Epstein-Barr or Lyme, or gut pathogens like C. difficile, due to weakened immune surveillance, which allows latent infections to flare. Mycotoxins can impair immune defenses against pathogens and disrupt the gut’s natural detoxification processes. This can lead to a whole slew of health issues such as inflammatory bowel disease and irritable bowel syndrome, as well as extra-intestinal diseases, including heart disease, obesity, type 1 diabetes and celiac disease.
Mycotoxins have also been connected to mast cell activation syndrome (MCAS), and histamine intolerance. So when I see histamine issues, my first thoughts are either mycotoxins or hydrogen sulfide producing bacteria.
What are the symptoms of mold toxicity?
The symptoms of mold toxicity are highly variable between individuals and can mimic gut symptoms, including abdominal pain, nausea and diarrhea. Respiratory symptoms, such as rhinitis, coughing, wheezing, sinus congestion and tenderness, and respiratory infections such as bronchitis and pneumonia, are frequently reported. Skin irritation and mucosal irritation, such as dry eyes and pharyngeal cobblestoning, are also commonly reported. Some individuals may experience headaches and sensitivity to bright lights. Some studies have also reported symptoms like anxiety, depression, muscle aches and cramps, joint pain with morning stiffness, unusual pains around the body, excessive thirst, a metallic taste in the mouth, weakness and fatigue. As mold toxicity progresses, some individuals may experience deficits in their neurological functioning, including deficits in short-term memory, executive function/judgment, numbness and tingling, disequilibrium and dizziness, and poor concentration and hand/eye coordination.
Mold toxicity, in conjunction with other health issues, may exacerbate other symptoms not usually related to mold toxicity. So while you may have some slight gut issues, if you pile mold toxicity on top of that, it can seem much worse and become impossible to resolve your gut issues until the mycotoxin issue is addressed first.
It is important to note that the symptoms attributed to mold toxicity are still debated, as many symptoms overlap with other conditions, many of them mundane.
How do you test for mold in your home?
If you suspect a mold issue in your home, relying on visual inspection alone is often insufficient. Mold spores themselves are microscopic and invisible to the naked eye, and mold growth can occur inside walls, under flooring, or in HVAC systems, where it cannot be seen without specialized tools. Humidity meters do not detect mold spores directly, but they can identify excess moisture and humidity levels, which create ideal conditions for mold growth. For a more comprehensive evaluation, ERMI (Environmental Relative Moldiness Index) and HERTSMI-2 tests, which analyze dust samples for mold DNA, are useful screening tools — especially for assessing past or cumulative mold contamination in water-damaged buildings. EnviroBiomics is a company that offers these tests (I believe you order the plates and lay them out in the house then send them back for analysis) and I’ll link to that in the show notes. However, they are not diagnostic on their own, and results should be interpreted alongside a thorough home inspection. One company that does mold inspections is called Environmental Analytics, and I’ll link to them in the show notes.
Air and surface testing can also help detect mold, with active air sampling being a common method where a pump draws air through a filter, which is then analyzed for mold spores and other pollutants. While air sampling provides a snapshot of airborne mold levels, it can miss hidden mold or fluctuating spore counts, so it is best used in combination with moisture mapping, thermal imaging, and targeted surface sampling. If you suspect mold damage, it’s highly recommended to hire a professional mold inspector, preferably one who is independent from any remediation company to avoid conflicts of interest. In states with mold regulations, such as Texas and Florida, this separation between inspection and remediation is required by law, ensuring a more objective assessment.
How do you test for mycotoxins in your body?
When I suspect mycotoxins, I use either the Mycotoxin Panel from US Biotek/Real Time Laboratories (which recently merged), the Mosaic Diagnostics Mycotox or Vibrant Wellness’ Mycotoxin Panel. These are all urine tests. For someone with ongoing nasal/sinus issues, I may also suggest a MicroGen DX SinusKEY test, which uses qPCR technology to check for 57,000 potential bacterial and fungal pathogens in the sinuses. I sometimes am also clued in to potential mycotoxin issues when I see elevations on the Mosaic Organic Acids Test in markers 2, 4 and 5, which are indicative of aspergillus, a type of mold that can be environmental. Vibrant Wellness’ Organic Acids test also has these same markers: 5-Hydroxymethyl-furoic acid, Furan-2,5-dicarboxylic acid and Furancarbonylglycine – you’re looking for the words furan or furoic in these longer, more complicated names for potential environmental molds.
However, these can often be negative while mycotoxin tests are positive because there are many different types of mycotoxins and most of them are not measured on an Organic Acids Test. Generally, I recommend testing your body before your home, as the various mycotoxin tests currently run from $289-$400 each, whereas a home inspection I’ve heard can cost around $500. Not to mention that you may be exposed to mycotoxins at someone else’s home that you visit frequently or at your place of work.
How do I heal from mold toxicity?
If you determine that you have a mycotoxin issue, the first step is to either get out of the moldy environment or have it professionally remediated. And I’d recommend that if you are very impacted by this issue, that you remove yourself from the home or building during remediation. You should never take care of this problem yourself, but hire a professional mold remediation service.
If you can’t get out of the environment or remediate immediately, you can take binders specific to the mycotoxins detected on your test until you can get out. Until then, it’s not recommended that you take antifungals, as this may be too much for your system to handle while still in a moldy environment, and will be futile, because you’re still taking in mycotoxins. However, taking binders on an empty stomach with plenty of water can help bind up the mycotoxins and prevent damage in the meantime.
If you’re doing this without the benefit of an MD or naturopath who has prescribing rights, the binders you’ll likely have access to will be activated charcoal, which binds ochratoxins, aflatoxins and trichothecenes (tree-co-thee-scenes) and bentonite clay, which binds, gliotoxins and aflatoxins, and Saccharomyces boulardii* (a probiotic yeast) and NAC, which bind gliotoxins. Chlorella and bentonite clay may help bind certain mycotoxins, including trichothecenes.
I often recommend Quicksilver’s Ultra Binder* or Biocidin’s GI Detox* as all-around binders with several of those compounds in them. If you’re very sick and/or sensitive, you may need to start with less than an entire capsule of binders to start, even ¼ capsule mixed in water for example, just to check your initial reaction. You may experience a die-off or Herxheimer reaction that feels like getting the flu. If that’s the case, I suggest you titrate up very slowly, but eventually, you should get to 1 capsule 3 times a day of binders, always on an empty stomach with plenty of water, with at least an hour before eating and two hours after eating or taking supplements. If you’re constipated, you may need to take additional magnesium citrate (I personally like the Natural Vitality Calm* powder, which is magnesium carbonate that turns to citrate in water) to promote bowel movements as binders can be constipating. You should get up to the full dose of binders before adding in any antifungal agents.
For many mycotoxins, supportive nutrients like vitamins C and E, selenium, zinc and magnesium are good to have on board before going through detoxification protocols. In addition, using NAC, glutathione,* CoQ10, melatonin and polyphenols can positively impact your health, protect your body from oxidative stress and open up detoxification pathways.
When it comes to helping clients actually kill the molds, I educate clients on the protocol developed by Neil Nathan, MD, who leans on the Dr. Brewer protocol, and described in his book Toxic: Heal Your Body from Mold Toxicity, Lyme disease, and Multiple Chemical Sensitivities, and Chronic Environmental Illness*. His protocol involves the use of Argentyn 23 (hydrosol silver) nasal sprays to start, to test sensitivity and then work synergystically with antifungal nasal sprays. He recommends prescription nasal sprays made by compounding pharmacies, because many molds have come from the air and may have settled in your sinuses. When those aren’t available, the Xlear* nasal spray (xylitol-based) with added drops of Biocidin* (10 drops per 1 ounce of spray) is a reasonable alternative, because Biocidin is a strong, combination antifungal agent. All nasal sprays start at one spray a day then go up to as many as 3 sprays per day, if you can tolerate it. And again, you don’t move on to the next stage until you can tolerate both binders and nasal sprays.
Dr. Nathan then recommends using prescription itraconazole (brand name Sporanox), a systemic antifungal, starting at a dose of 100 mg every two weeks and slowly working up to 1-2 doses per day.
When prescription options aren’t available, Biocidin* drops are again a good option, starting with 1 drop a day and working up to 15 drops twice a day or 10 drops three times a day, 15 minutes before meals. Other natural antifungal agents include berberine, oregano oil, grapefruit seed extract and undecylenic acid (primarily targeting Candida). Most of these are very strong antibacterial agents as well, so it’s wise to protect your microbiome with supportive prebiotic foods while taking them, like pomegranate powder, cranberries or cranberry powder and matcha green tea powder.
I often suggest clients combine these into a gut healing smoothie with collagen, l-glutamine and any other powders people may be taking like AuRx*, a palatable butyrate powder which helps firm up stool for people with loose stool or diarrhea as well as helping seal the colon, and serum bovine immunoglobulins, which can help bind fungi and pathogenic bacteria and and support gut barrier function. This combo can help seal up a leaky gut and protect you from autoimmunity and inflammation. A diverse probiotic with well-researched strains may also help with gut health during a mold protocol. I like Seed Synbiotic* as a general lacto-bifido type probiotic.
Dr. Nathan also adds SFI Health Ther-Biotic Interfase Plus* to disrupt biofilms. I think it’s wise to wait until you’ve gotten to the point of tolerating daily doses of antifungals before starting this, as it may increase die-off. This is taken by itself with water on an empty stomach an hour prior to antifungals.
Other helpful modalities for supporting detoxification from mycotoxins include infrared saunas, coffee enemas and lymphatic drainage using self-massage or dry brushing, and any activity that will make you sweat, while bringing in adequate hydration and electrolytes of course. There are links for those things in the show notes.
There are lots more details about how Dr. Nathan treats mold, so if you are thinking of self-treating or trying to ask your conventional doctor for prescription antifungals, I’d recommend getting his book before launching into this project, although it’s much safer to work with a practitioner and have guidance as things often go differently than expected/planned when taking supplements and medicines.
I mainly wanted to take this time to alert you to the idea that your gut health issues could have their roots in mycotoxins, as sometimes I’m not even thinking about mycotoxins unless you suggest it may have been an issue, and only you will know about potential mold exposures in your past or present. So do be proactive with me or whoever your practitioner is if you’re experiencing symptoms like I described in this podcast, have recalcitrant gut issues or remember living in a moldy, mildewy place in the past.
If you’re dealing with gut health issues of any type (diarrhea, constipation, bloating, SIBO, IMO, H2S SIBO/ISO, IBS, IBD, gastritis, GERD, H pylori, diverticulitis, candida, etc.) or have an autoimmune disease and need some help, I see individual clients to help them resolve their digestive issues or reverse autoimmune disease naturally, You’re welcome to set up a free, 30-minute breakthrough session to see if you’d like to work with me. I also have my own two products, Tributyrin-Max, which is particularly helpful for loose stool and diarrhea as it slows your motility and firms up your stool, and SBI powder, which is an all around gut pathogen binder, which is super safe and won’t harm beneficial bacteria, and is usually the first line of treatment I educate my clients about in order to avoid stronger antimicrobial herbs.
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