Mold is a natural part of our ecosystem, but it can be a nuisance in the kitchen. We've all encountered moldy food before, whether it's a forgotten piece of fruit gone green, a berry coated in fuzz or a blue-speckled slice of bread at the end of the loaf. While mold growing on food is normally a sign of spoilage, mold is also intentionally present in some foods. Specific mold species are used to make gourmet cheeses, for example. Mold gives gorgonzola its characteristic blue-green veins and pungent flavor — and it's actually mold that forms the firm, white rind encasing brie cheese. Excluding these purposefully moldy delicacies, food that is growing mold usually goes right into the trash. The taste and texture of mold is unpleasant, and the sight alone is enough to give someone the ick. However, maybe you decided to cut off the green and blue bits to salvage the edible parts — which is reasonable given the price of groceries these days. Perhaps you didn't notice there was mold growing on your food until after you took a bite or finished your meal. We’ve all accidentally eaten some moldy food at some point. Aside from being grossed out, you may have concerns about the health effects. What happens if you accidentally eat mold? Can moldy food make you sick, and if so, how much mold does it take? And where do foods like blue cheese stand? We spoke to experts about why mold grows on food, what happens to the body when you eat mold, and how to keep your food fresh and mold-free. What is mold? Mold is a type of microscopic fungi, Josephine Wee, Ph.D., an assistant professor of food science at Penn State University, tells TODAY.com. Fungi are a group of microorganisms that also include mushrooms and yeast. Molds are a natural part of the environment and found almost everywhere moisture and oxygen are present, per the U.S. Environmental Protection Agency. Outdoors, molds play an important role by breaking down decaying organic matter, like dead plants, and recycling the nutrients. Indoors, mold can spoil foods and grow on damp surfaces and should be avoided, according to the EPA. There are tens of thousands of species of mold, which spread by producing tiny spores. "The spores are everywhere; they are on our skin, in the air that we breathe, on our foods," says Wee. Why does mold grow on food? Once mold spores find a host to live on, such as a piece of food, they'll grow in the right conditions. “Molds like higher humidity and warmer temperatures,” says Wee. This is why mold does not form as quickly on food that’s dry or refrigerated. Molds, like other living microorganisms, also need oxygen to grow, Randy Worobo, Ph.D., professor of food microbiology at Cornell University, tells TODAY.com. Foods with a high-moisture content, such as cheese, often come vacuum-packed because mold can grow soon after products are exposed to air, he explains. “One of the unique characteristics of molds is that they’re really good at growing on just about anything. ... They’re scavengers,” says Worobo. Which types of mold are harmful? There are many different types of mold. "There's the good, the bad and the ugly (or toxic)," says Wee. "Good" molds are used to manufacture some medicines, such penicillin, and foods like dry-cured salami or cheeses. “These are intentionally added to the milk cultures,” says Wee. A mold called penicillium roqueforti is used to make blue cheeses like roquefort and gorgonzola. Penicillium camemberti is used to make soft camembert and brie cheeses, which have a white mold surface, Worobo explains. The mold in and on these cheeses is safe to eat, according to the U.S. Department of Agriculture. "Bad" mold grows on food due to spoilage, especially if there's excess moisture, says Wee. Food mold comes in many colors and textures. On bread, it often looks like blue or black dots, but mold on citrus fruits looks like velvety green patches, per the USDA. Moldy berries and jam often have a cotton-like gray fuzz. Mold can also look red, pink or orange, and the color can change over time depending on the mold’s life cycle, says Wee. Toxic molds can produce harmful substances called mycotoxins under the right conditions, says Wee, which can cause allergic reactions and respiratory problems. These include black mold, which can grow on foods but normally lives on wood and drywall, per the Cleveland Clinic. It’s impossible to tell which type of mold is growing on food or whether it is toxic by looking at it, the experts note. What happens if you eat mold? The taste of mold is typically unpleasant or described as an earthy, dirt-like flavor, says Wee. But other than ruining your meal, usually nothing happens if you eat food with mold on it, the experts note. “When you ingest the food mold, the acids in your stomach, as well as the digestive enzymes, will break the cells down," says Worobo. Healthy individuals likely won’t get sick or notice any symptoms. “For the general population, it’s not a big deal,” Worobo adds. However, in immunocompromised people, mold can potentially colonize and result in fungal infections, so these individuals should be extra careful, the experts note. Some people are allergic to common types of food mold, so eating moldy food may cause a reaction, the experts note. Symptoms may include sneezing, a runny nose, or an itchy throat, according to Mayo Clinic. Exposure to toxic molds can cause adverse health effects in the short- and long-term, per the World Health Organization. The most dangerous type are aflatoxins, which can be carcinogenic, per the USDA. These are less common. How much mold can make you sick? The average person likely won't get sick from ingesting small amounts of mold, the experts note. However, eating larger quantities of mold may result in nausea or stomach upset. Chances are you won't be able to eat very much mold because humans have a natural aversion to spoiled foods, Wee notes. "You're not going to eat a slice of moldy bread because it does not taste good, and it's not appealing to the eye. It's a sensory issue," she adds. Ingesting large doses of certain mycotoxins can cause poisoning or liver damage, per the WHO, but this is very rare. People who are allergic to food mold cannot eat any amount, the experts note. “Even if there are no toxins present, they cannot eat even small amounts (of moldy food) due to the spores,” says Wee. Can you cut around moldy food? The mold you see growing on the surface of food may penetrate much deeper. Think of the roots of a tree growing underground, says Wee. The body of mold consists of a root that invades the food, a stalk that rises above the food and may not be visible to the naked eye, and spores that form at the end of the stalks, according to the USDA. (The spores are what you see growing on the food.) The softer the food, the easier it is for mold to penetrate. Cutting out or around mold on foods may not get rid of it, the experts warn. In fact, slicing a knife through a moldy spot can spread the spores to other parts of the food, says Worobo. Spoiled, moldy foods may also contain bacteria that can make you sick, which are not visible. To be safe, toss any food that is growing mold or touching other moldy food, says Wee. The USDA also recommends discarding food covered in mold, but outlines a few situations where certain foods may still be used if the mold growth is minimal: Hard cheeses (i.e. cheddar or parmesan): cut at least one inch below the mold, avoiding cutting into the mold itself, and re-cover in a clean wrap.Firm fruits or vegetables (i.e. carrots or cabbage): cut at least one inch below the mold spot and use immediately. Avoid sniffing moldy food, because you can inhale the spores, the experts note. When to see a doctor if you’ve eaten mold If you've ingested moldy food, don't panic, the experts say. Unless you're immunocompromised or ate a very large quantity of mold, you'll probably be OK, but watch for any symptoms in case. If you develop severe gastrointestinal symptoms or signs of an allergic reaction, seek medical attention. These include but are not limited to vomiting, shortness of breath, or a high temperature, per the Cleveland Clinic. In any case, if you have concerns or questions about eating mold, always talk to your doctor. How to prevent mold on foods There simple steps you can take to prevent mold growing on foods and reduce your risk of exposure to mold, according to the experts and the USDA, including: Examine food for signs of mold before buying.Store food in airtight containers or plastic wrap.Refrigerate perishables at 40 degrees or lower.Refrigerate cooked food within two hours of serving.Clean surfaces and containers moldy food has touched.Cover foods while serving to prevent exposure to spores.Use or discard leftovers after three to four days.
