It’s estimated that as many as 47% of buildings in the United States have some mold exposure [1]. Unfortunately, that means there’s a good chance your environment also has mold.
We’re exploring mycotoxins and the potential health effects of mold exposure, including the relationship between mold and gut health. Exposure to mold across your lifespan, but especially in early life (and even during pregnancy!) may increase your risk of atopic disorders, such as eczema, allergies, and asthma.
There’s an upside. A strong gut microbiome can help protect you against the side effects of mold. Read on to learn more.
What are Mycotoxins, and how mold enter the body
You may recognize the names of a few common molds, like Aspergillus and Penicillium, but many others can affect you depending on your environment or exposures. Wet or humid environments can easily lead to the growth of a variety of molds [2]. All mold needs to thrive is a bit of moisture and some nutrients. Nutrients can come in many forms, but home materials like carpet, wood, or even ceiling tiles can support mold growth. Moisture often shows up after a major rainstorm or even a flood, but can also accumulate over time in high-humidity environments. You can also be exposed to molds through contaminated foods [3].
So what are mycotoxins? Many molds have the potential to cause harm and do so by producing metabolites called mycotoxins (“myco” means fungus, so mycotoxins are toxins from fungi like mold). Once these toxins enter your body, they can cause damage to different systems in your body.
Molds release spores to reproduce, so a common way you can be exposed to mycotoxins is through inhalation of these mold spores [4]. When this occurs, mycotoxins are likely to affect your lungs, bloodstream, immune system, and even your brain [5]-[8]. This is often how mold affects people when it's present in their homes.
If mycotoxins are eaten on a piece of moldy food, their first line of attack will be in your gut, before traveling to the rest of your body [9]. Studies have shown that they can open up passage through your protective gut barrier by reducing the mucus layer and breaking down your epithelium [10]-[12] as well as dysregulate the immune system in your gut by throwing off the balance of pro- and anti-inflammatory cytokines [13]. They may also hurt your gut microbiome.
However, it’s important to note that unless mold is ingested through contaminated food, current gut microbiome testing methods (such as stool tests) are not well-equipped to detect mold directly. Mold exposure that occurs via inhalation can certainly influence gut health indirectly by increasing inflammation or disrupting immune balance, but it won’t necessarily show up in your gut test results. In these cases, a urine or blood test for mycotoxins may offer a more reliable method of assessing mold exposure or toxicity [14].
How can mold and mycotoxins affect your health?
Early-life mold exposure may sensitize the immune system, increasing the risk of atopic disorders such as eczema, allergies, as well as asthma [15]. This happens when components of the mold structure, like mold spores, for example, are detected by your body as allergens, leading to a larger-than-necessary response by your immune system [16]. These mold components can also cause inflammation throughout your body.
Eczema is associated with exposure to molds, such as Aspergillus [17] in the first year of life [18]-[20]. It is also possible for exposure to mold during pregnancy to increase the risk of eczema later in childhood [21].
Food Allergies [22], [23] or other irritants like pet dander or tree pollen [24] can worsen with mold exposure. In addition, mold exposure in a damp household is associated with an increased risk of allergic rhinitis in both children and adults [25], [26].
Asthma has the strongest association with mold exposure. Several studies have shown that exposure to mold during the first two years of life increases the risk of asthma development by the end of childhood [2], [27]-[31].
Research shows that early-life mold exposure before 1 year old has the highest risk for asthma. One study showed that mold exposure at 1 year of age, but not 7 years of age, increased the risk of asthma at 7 years of age [32]. Common indoor molds like Penicillium, Aspergillus, and Cladosporium may be specifically responsible for the increased risk of asthma [33].
The season of your baby’s birth may play a role in their exposure to mold. This is because the fall and winter months are when molds and fungi release their spores into the air. Babies born during this period are more likely to be exposed to mold during the crucial early life period. Babies born in these winter months are also at increased risk for atopic conditions [30], potentially due to their exposure to mold, alongside other factors like pollen exposure, and incidence of illness.
Can mycotoxins hurt—or even help—my microbiome?
Research on the effects of mycotoxins on the human microbiome is extremely limited. However, knowledge from studies in animal models can help us to understand the possible effects of mold exposure on the human gut microbiome.
Notably, not all molds are harmful. Penicillin, a significant medical breakthrough, was discovered by Alexander Fleming on a moldy Petri dish in 1928. This accidental discovery highlighted the potential benefits of molds.
Antibacterial properties
Mycotoxins themselves can have antibacterial properties, meaning that they can kill bacteria. In some cases, we’ve been able to use this to our advantage. The life-saving antibiotic Penicillin was originally derived from a mold, Penicillium, by Alexander Fleming because of its natural ability to kill pathogenic bacteria [34]. Today, penicillin is synthetically produced in labs, bypassing the need for mold altogether. Other molds, such as Myxomycetes and Fusarium [35], [36], also have this unique antibacterial ability.
Unfortunately, this means that it is also possible for environmental exposure to mycotoxins to degrade the beneficial bacteria in your gut. When mycotoxins attack your gut barrier, this sends alarm signals to the gut. Unfortunately, in many cases, these signals may degrade your gut microbiome [13].
Support of pathogens
After the beneficial bacteria in your gut are killed off, a niche is left open that is often filled by more unfriendly bacteria. Animal studies have shown that mycotoxin exposure can increase the likelihood of these unfriendly bacteria taking root in your microbiome [37].
Luckily, a robust gut microbiome is a great defense against invading mycotoxins [38].
Ways to protect yourself from mold exposure
Control indoor moisture. The number one cause of household mold is moisture, whether that be from a high-humidity climate or a leaky pipe. Attacking the source of moisture within your home should be your first step to preventing mold.
Test for mold. If you have noticed a damp area or a musty smell in a certain room of your home, it may be wise to test for mold. Both at-home and professional tests are available.
Filter out the spores. If a mold problem is already present at home, spores from that mold will circulate in the air, potentially increasing the overall fungal load in your home. Consider a HEPA-grade air purifier to remove these microscopic spores from the air in your home.
Seek mycotoxin treatment. If you feel you may be having a reaction to mold in your home, a visit to your healthcare provider may be in order.
In some cases, your provider may recommend specialized testing, such as blood or urine mycotoxin analysis, to help assess exposure. These tests may be particularly useful if your symptoms are ongoing but gut or allergy tests haven’t provided clear answers.
Because of how common mold is in our environment, chances are you have been exposed at some point in your life. Keep reading to learn how your gut microbiome plays a role in keeping you healthy.
Your gut microbiome: bacteria, viruses, and…fungi? Meet your mycobiome
So, we've talked about bad mold exposure, what about good fungi? Are there any fungi that are supposed to be in your gut? The answer is yes! This little-known microbial community is sometimes referred to as the “mycobiome.” In most cases, this group of fungal species makes up less than 1% of your microbiome and often doesn’t show up on a shotgun metagenomics test because the individual species may make up such a small fraction of your sample. This may sound scary, but at low levels, most fungal species can coexist with the rest of your microbiome without causing any harm.
Researchers have made efforts to understand what fungal species populate a healthy gut during the first months of life. Here’s what they’ve found:
- Babies in the first month of life likely have mostly Candida [39], Cryptococcus, and Saccharomyces [40] in their mycobiome.
- Babies between 1 and 3 months begin to grow Malassezia and Cystofilobasidium [38], as well as Debaryomyces during the period that they are still relying on breastmilk or formula for nutrition [41].
- Babies up to 1 year and older may have higher levels of Trichosporon [38], but Saccharomyces may dominate instead if they were born by a c-section birth.
Even though fungi make up a small portion of your microbiome, their composition can have a big impact on your health. Unsurprisingly, a shift in your mycobiome can cause negative gastrointestinal symptoms [42], but they can also have impacts on your immune system and metabolism [43], [44], or even your brain [45], [46].
Strengthen your microbiome defense against mycotoxins
If all this talk about mold and toxins has you worried, you’re not alone. We come bearing good news! Having a healthy gut can help protect you from the side effects of mold exposure.
Your gut microbiome can tamper with the toxic effects of mycotoxins by either holding them captive so they can’t infiltrate your gut barrier and reach the rest of your system or by transforming the mycotoxins into new forms that are no longer toxic [13]. That’s the power of your gut.
Not sure of your gut health? Our gut health test gives you a comprehensive look into your microbiome. You’ll learn about your (or your child’s) unique mix of beneficial and disruptive microbes and health conditions associated with any imbalances. Then you’ll get a personalized action plan with recommendations for foods, supplements, and lifestyle changes to help your gut thrive.
