How Does Mold Affect Food?

If you're contemplating eating the last piece of bread and notice just a bit of mold on the crust, cutting it off and eating the bread anyway might seem like a viable solution. You might regret it, though, because mold can make you sick, and its roots extend farther into a food than you can see. Although you can safely cut mold off some foods, it's risky to do so in others. "When in doubt, throw it out" is the safest motto.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.

Types of Mold

Mold exists in more than 300,000 forms, but the harmful byproducts of molds, called mycotoxins, number only 30 or so. As much as 25 percent of the world's food is contaminated with mycotoxins, the Food and Agriculture Organization of the United Nations estimates. Grain and nuts are most often contaminated with mold, but produce such as apples and grapes can also be sources of mold.


Not all types of mold on food can make you sick. Molds such as Penicillium roqueforti create cheeses such as blue, Stilton and Roquefort cheeses. However, molds such as aflatoxin, which infects corn and peanuts, among other foods, can increase your risk of developing cancer. Regulatory agencies such as the U.S. Food and Drug Administration and the U.S. Department of Agriculture monitor aflatoxin levels in peanuts and corn. Other toxins, such as ergot, can cause hallucinations and other neurological issues. Mycotoxins can also cause gastrointestinal, skin and vision side effects. People with compromised immune systems, the elderly and the very young are most susceptible to mycotoxin infections upon exposure.

Eating Foods With Mold

Molds often affect foods far below the surface mold you can see and scrape off, which means it could spread to where you can't see it, so scraping off the mold often isn't enough to ensure you won't consume any of it. It is safe to cut mold off of harder cheeses, such as cheddar and Colby, because the mold can't spread that far into them. Cut away at least an inch, not only around the mold, but also below the moldy spot, registered dietitian Katherine Zeratsky of recommends. Molds can grow beneath the surface in cooked casseroles, lunch meats, grains -- including bread -- jams, fruits and peanut butter. Do not eat these even if you remove the moldy area.


If a food develops mold, don't even sniff it to see if it smells spoiled. Molds can enter the respiratory tract and cause respiratory problems. If one food in your refrigerator is contaminated by mold, check nearby foods because mold spores spread easily and quickly.