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The Top 7 Food Sources for Mold

by Amanda Demsky
moldy food sources

While you may be familiar with the visual evidence of mold growth on foods that have obviously turned, are you aware that some foods are guaranteed to come pre-contaminated with mold before they’ve even had a chance to expire or rot? In this article, we’ll be discussing the top eight foods that contain mold—otherwise known as mycotoxins.


What are Mycotoxins?

Mycotoxins are the secondary metabolite of molds—basically, mold’s toxic chemical byproduct. They become the airborne allergens that can cause serious health problems, such as skin infections, respiratory diseases, and autoimmune disorders. While many different types of fungus can produce these toxic substances, mold is the primary culprit.

There are thousands of known mycotoxins in the world, but only a handful are associated with food safety risk. Typically, these toxic metabolites are found in grains and nut products.

What’s most worrisome is that food mycotoxins are chemically stable, which means they can survive the hots, colds, and chemical additives of food processing. They are also incredibly difficult to detect, even with the best testing.

How Can You Become Exposed to Food Mycotoxins?

Obviously, the most direct route of exposure is by eating foods infected with mold growth. An indirect route, however, is by eating the flesh or dairy products of animals that were fed mold-contaminated feed (such as grains).

The Discovery of Food Molds

It isn’t as if food molds or mycotoxins weren’t always around—they were. But, as the study of microbiology improved, its existence was eventually discovered. Scientists of antiquity were noticing that certain foods often played a major role in outbreaks of disease, though it took them some time to realize these foods were infected with the effects of toxic mold. Due to unsanitary food preparation and storage, plenty of foodborne illnesses often plagued entire communities—many the result of mold (though bacteria tended to be the leading contributor).

One notable incident that arose not just from unsanitary food practices, but from exposure to naturally-derived food fungus, occurred in the Middle Ages. For a time, rye bread—whether baked at home or purchased from the market—was heavily contaminated with a fungus now known as ergot. Ergot fungi are a genus of Claviceps (namely C. purpurea) that regularly infect cereal plants, such as rye and wheat. Their growth is actually quite visible on the heads of the rye and wheat grasses—they appear as black bundles.

Once the infected crop is harvested and stored in hot, damp silos, the fungus simply proliferates further and produces the mycotoxins that can cause pandemic-level health concerns in entire regions and communities. This is precisely what happened in the Middle Ages. In fact, we encourage you to watch for an upcoming article on it here on MoldBlogger. This particular epidemic was known as Saint Anthony’s Fire because it caused burning sensations in the limbs of its victims.

Needless to say, it is quite imperative that we become well-acquainted with the foods that are more prone to develop mold growth and facilitate mycotoxin transference, such as the cereal grains rye and wheat.

What are the Health Risks Associated with Mold in Foods?

Symptoms of toxic mold in food can be acute or chronic, mild or even life-threatening, depending on a person’s preconditions.

Individuals with compromised immune systems and any pre-existing conditions should be even more careful of protecting themselves from mold in food. Healthier individuals may experience mold sickness and allergy-like reactions to mold, but those already in poor health will face infection and, quite possibly, death.

Pre-Existing Conditions Most Vulnerable to Mold Exposure

• Allergies
• Asthma
• Chronic Obstructive Pulmonary Disorder (COPD)
• Chronic lung disease
• Cystic fibrosis
• Depression
• Diabetes
• Heart defects
• Insomnia
• Kidney Failure
• Liver failure
• Sickle Cell Disease
• Seizure disorders
• And much more…

Acute Symptoms Noticed at the Beginning of Mold Exposure:

• Asthma
• Chest and nasal congestion
• Coughing, sneezing, and wheezing
• Diarrhea
• Headaches
• Shortness of breath
• Sore throat
• Skin irritation
• Vomiting
• Watering, dry or sore eyes

Severe and Chronic Conditions Caused by Exposure Over Time:

• Cancer
• Digestive and heart conditions
• Immune and blood disorders
• Impaired brain function
• Liver and kidney conditions
Neurotoxicity (toxic nervous system)
• Pulmonary bleeding
• Pulmonary fibrosis (scarring in the lungs)
Teratogenic (pregnancy and fetal/embryonic conditions)
• And much more…

What are the Top 7 Foods that Contain Mycotoxins?


1. Whole Grains: corn, wheat, barley, rye, and rice.

Grains, especially livestock feeds, are the most common source of food mold.

2. Nuts: peanuts, pistachios, and Brazil nuts.

Probably the most well-known source of aflatoxins are peanuts. We have an article regarding peanut mold here on MoldBlogger.

3. Dried Fruits: figs, dates, raisins, and prunes.

Dried fruits are notorious for mold contamination. A study discovered that over 80% of the dried fruits investigated were contaminated with mycotoxins.

4. Aged, Dry-Cured Meats: salami and sausage.

What’s disturbing is that molds don’t have to grow on the meat directly, but can be introduced into the meat long before slaughter, due to the animal eating mold-infected feed. What’s even more disturbing is the fact that aged and dried meats are an unregulated industry that is almost always guaranteed to carry mold-infested products.

5. Hard Cheeses

This moldy food is a no-brainer. Some cheeses are actually anticipated to be mold-ripened for flavor and effect—these can still harbor deadly mycotoxins. All hard cheeses are at risk for mold contamination because of the process by which they are ripened, as well as the source of the dairy (i.e. livestock fed mold-infested feed).

6. Coffee Beans

There is substantial evidence that all coffee products contain mold. This is because the toxic compounds of the aflatoxin and ochratoxins in coffee beans are able to survive every part of the process from roasting to brewing. We have an article concerning mold in coffee here in MoldBlogger.

7. Alcohol

For alcohol, we again revisit the issue of grains, namely barley. And, once more, we are faced with the frightening reality that mycotoxins survive the processes by which this and other products are prepared for consumption.

No matter what a company claims, most distilleries choose the grains that were so infected with mold that they were unfit for regular food production. This allows them to buy at a steep discount. They can make claims of it being “organic” or “ethically-sourced,” but that doesn’t mean their products are mold-free.

If you’re curious about moldy alcohols, read these studies:

Different wines on six different continents contained mycotoxins.
Drinking beer exposes the consumer to high levels of mycotoxins.

At What Point Does Mold Grow on These Foods and Food Products?

Mold growth can occur at several different stages of food production:

• Prior to harvest
• Post harvest
• While in storage
• Anytime food is held for too long in damp and humid conditions

Essentially, mold growth occurs when crops are contaminated before harvest or after harvest. Like the ergot fungi that affected the rye crops in the Middle Ages, some molds are introduced before a crop is even pulled. But, most incidents of mold growth and mycotoxin contamination begin in crop storage, such as the hot and damp silos. For some foods, such as many grains, mold infection is unavoidable and the consumer will be responsible for counteracting the effects by consuming other products alongside those foods, such as chlorophyll.

If you’re interested in discovering how to minimize your risk for mycotoxins in these foods and more, stay tuned or—if you’re a little late reading this—try using our helpful search bar to find “How to Minimize the Risk of Foodborne Molds.”

For more information regarding mold, mold prevention, and mold solutions, please check out the rest of MoldBlogger.com.

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