Is Moldy Food Dangerous? Not Always

Mold is a type of fungus that grows on many different types of foods. Some common examples are:

Bread (including wheat)

Cereal (especially corn and rice)

Cheese (e.g., cottage cheese, cheddar, gruyère, etc.)

Ice cream/frozen yogurt (e.g. Ben & Jerry’s, Hershey’s, Nutella)

Milk (e.g., soy milk, almond milk)

Meat (e.g., ham, bacon, sausage)

Soup or stock (e.g., tomato soup or chicken broth)

There are other types of fungi that grow on certain foods but they do not cause illness unless eaten in large quantities such as when eating moldy bread.

Inhalation of mold spores from foods can cause symptoms similar to those caused by food poisoning. Symptoms include nausea, vomiting, diarrhea, abdominal cramps and fever. Other possible signs may include headache, chills and fatigue. The severity of these symptoms depends on how much mold was ingested and where it came from. If you have any questions about whether something might be harmful to your health or if you think someone else may be at risk contact your local public health department immediately.

Like any living organism, molds need moisture to grow. Mold generally begins to grow when there is excess moisture present in food. Food can become contaminated with mold when exposed to:

Water (e.g., flood water from a leaky pipe)

Condensation (e.g., in the refrigerator)

Leaks (e.g. a roof leak or a dishwasher leak)

Common storage areas for food (e.g., basement, garage)

Pets can also bring mold into your home on their fur and paws (e.g., from walking in dirt outside). This often happens during the summer when it is especially humid and the pet stays inside for long periods of time (e.g., after a bath).

Is Moldy Food Dangerous?

Not Always.

The main concern with eating moldy food is that it can make you sick. If you eat enough of it, the mold can produce toxic substances that can severely affect your liver, kidneys and other organs. In some cases, this can lead to death. How sick you are and how much damage the mold does depends on what type of mold it is and how much of it you ingested. Common molds (such as penicillium) do not produce toxic substances but other types of molds (such as aflatoxins which can be found in peanut butter, nuts and other foods) are known to be harmful if ingested.

One mold in particular, called patulin, is especially dangerous because it is known to cause cancer. While it is not common in food, it can be found in apple juice which has been left out for a long time.

Determining if Moldy Food is Still Safe to Eat

There are several factors that will determine how harmful moldy food is to your health.

Sources & references used in this article:

Flooding and human health: the dangers posed are not always obvious by CA Ohl, S Tapsell – 2000 –

… /tandem mass spectrometric multi-mycotoxin method for the quantification of 87 analytes and its application to semi-quantitative screening of moldy food samples by M Sulyok, R Krska, R Schuhmacher – Analytical and Bioanalytical …, 2007 – Springer

Mould and yeast flora in fresh berries, grapes and citrus fruits by VH Tournas, E Katsoudas – International journal of food microbiology, 2005 – Elsevier

Mycotoxin migration in moldy foods by M Coton, P Dantigny – Current Opinion in Food Science, 2019 – Elsevier