Take a bite of something fuzzy or a little pungent? Experts explain exactly what happens if you eat mold and how to react safely.
About the experts
Lona Sandon, PhD, RDN, LD, is an associate professor in the Department of Clinical Nutrition at the University of Texas Southwestern Medical Center and is the Director of the Master of Clinical Nutrition Coordinated Program.
Zoe Weiss, MD, is an infectious disease physician and the Director of Clinical Microbiology at Tufts Medical Center. She’s also an assistant professor of Medicine and Pathology and Laboratory Medicine at Tufts University School of Medicine.
Julia Zumpano, RD, LD, has been a registered dietician at the Cleveland Clinic Center for Human Nutrition for almost 20 years, specializing in disease prevention and management.
Highlights
Accidentally eating mold isn’t usually a cause for concern—but some types of mold are dangerous.
Certain people are more at risk for getting sick from eating mold.
Some foods can be salvaged after mold appears, though many items are no longer safe to eat.
Experts explain what to do if you eat mold and how to prevent moldy food.
Nothing will kill your appetite faster than biting into a sandwich and spotting a patch of green, fuzzy mold moments too late. The thought alone of what happens if you eat mold might make your stomach turn—and make you unsure if that’s a side effect or not.
Fortunately, accidentally eating mold generally isn’t a huge cause for concern, according to experts. “We all have probably bit into a strawberry with a little mold on it and just noticed an unpleasant taste without symptoms,” says Lona Sandon, PhD, RDN, LD, an associate professor of Clinical Nutrition at UT Southwestern.
Still, while a fuzzy spot usually only spoils your meal, it’s best to toss most food with signs of mold. While uncommon, “it can be dangerous to consume mold depending on the type,” says Julia Zumpano, RD, LD, a registered dietitian with the Cleveland Clinic Center for Human Nutrition. Ingesting mold poses a greater risk for some people as well.
What is mold and why does it grow on food?
Foodborne mold refers to microscopic fungi that grow on food, often appearing as fuzzy green, white, blue, or black spots, explains Zoe Weiss, MD, Infectious disease physician and Director of Clinical Microbiology at Tufts Medical Center. “Think about the green fuzzy spots you see on bread that has been sitting on the counter for too long.”
Mold is present everywhere in the environment but thrives in warm, moist conditions. “Mold likes to grow on moist surfaces and will more easily grow on food that is not stored at proper temperatures or is just kept too long,” Dr. Sandon says.
Not all mold is bad—in fact, some molds are used intentionally in food production, like those in cheese, Dr. Weiss says. But even when it pops up where it’s not supposed to be, she says the vast majority of foodborne mold isn’t dangerous for most people.
However, some molds are harmful when ingested. While rare, certain types produce a poisonous substance called mycotoxins. These toxins can cause long-term health issues, such as certain cancers or kidney problems, if consumed repeatedly or in high amounts, Dr. Weiss says. “You can’t tell by sight or smell whether a mold is safe or dangerous,” she explains. “Toxic molds can look just like harmless ones.”
Fortunately, mycotoxin poisoning in the U.S. is rare. The Food and Drug Administration (FDA) monitors for several mycotoxins to prevent food from being sold that may be contaminated, Dr. Weiss says.
What happens if you eat mold?
“Most healthy people won’t experience any serious side effects from a small amount of mold,” Dr. Weiss says. “Maybe a bad taste or mild nausea.”
But if the mold produces mycotoxins—and remember, you can’t tell by sight, taste, or smell if it does—eating it can cause sudden respiratory issues or an allergic reaction, Zumpano says. If there are no mycotoxins present, you may still feel some gastrointestinal (GI) upset from eating mold.
However, people with a mold allergy (if you experience symptoms from mold in the air, for example) should be extra careful to avoid moldy food, Dr. Sandon adds. “Eating moldy food can lead to unpleasant symptoms such as diarrhea, vomiting, or itching, rash, and difficulty breathing if you’re allergic to mold.”
Still, one group in particular is most susceptible to potential health problems from eating mold: immunocompromised individuals. “For people with weakened immune systems, ingesting or inhaling viable mold spores—even of typically harmless molds—can pose a risk of serious infection,” Dr. Weiss explains. “If you have had an organ transplant, for example, you should be careful not to eat or handle any mold.”
Moldy food can also harbor harmful bacteria, Dr. Weiss says—and that poses a risk to anyone. “The same moisture and conditions that promote mold growth often allow bacterial proliferation, such as Listeria or Salmonella, increasing the risk of foodborne illness.”
Foods where eating mold is more dangerous Edalin/Getty Images
“One famous mold toxin (mycotoxin) is called aflatoxin, which is a toxin produced by a common mold species called Aspergillus flavus and Aspergillus parasiticus,” says Dr. Weiss.
These molds most often grow on grains, nuts, and legumes in warm environments. Corn and peanuts are particularly susceptible, Zumpano says. “And cooking doesn’t necessarily destroy the toxin,” adds Dr. Weiss. Aflatoxicosis is poisoning caused by ingestion of aflatoxin, and regular ingestion is associated with an increased risk of liver cancer, birth defects, and kidney and immune system problems, according to the FDA.
That said, Dr. Weiss says that aflatoxin poisoning is virtually unheard of in the U.S. due to strict food storage guidelines and regulatory oversight.
“Aflatoxin levels are tightly regulated by the FDA, and commercial food producers must adhere to maximum residue limits, so at the point of sale, they are safe to eat,” she explains. Still, it’s strongly advised to throw away moldy grains, nuts, or legumes to prevent any risk. (And it’s a good idea to keep up-to-date with FDA product recalls in the rare event mycotoxins slip through their monitoring systems. Get The Healthy by Reader’s Digest newsletter to stay informed.)
Dr. Weiss also says to toss any “soft foods” with mold present. “[These] contain high moisture and a looser structure, which allows mold to spread below the surface,” she says. “They may also harbor harmful bacteria, not just mold.”
According to the USDA, discard these foods at the first sign of mold:
Bread and baked goods
Lunch meats, bacon, or hot dogs
Soft fruits and vegetables, such as cucumbers, tomatoes, and peaches
Soft cheeses, such as brie, camembert, gorgonzola, blue, cottage, and cream cheeses
All types of crumbled, shredded, and sliced cheese
Jams and jellies
Legumes and nuts, including peanut butter
Unfortunately, this guideline is true even if you just have one or two spoiled strawberries or a slice of moldy bread in a pack. “Mold is microscopic and can still have infected the other produce that does not have visible mold,” Zumpano explains. The best strategy is to discard the entire pack.
However, some foods can still be safe to eat after cutting or scraping off moldy sections, Dr. Weiss says. “Hard cheeses or dry-cured meats like salami, for example—because mold generally does not penetrate deeply into dense, low-moisture foods,” she explains. “In these cases, it is recommended to cut at least 1 inch around and below the moldy spot.” For firm fruits and vegetables—like apples, bell peppers, and carrots—the same approach applies.
The USDA says that these foods are okay to eat after removing mold:
Hard salami and dry-cured country hams
Hard cheeses, such as cheddar, parmesan, and Swiss
Firm fruits and vegetables, such as cabbage, bell peppers, and carrots
What to do if you accidentally eat mold
If you realize you’ve just eaten a moldy bit of food, don’t panic. “Accidental ingestion of a small amount of mold is usually not dangerous,” Dr. Weiss assures us. “Spit out the food if it’s still in your mouth, drink water, and monitor for symptoms.” To play it safe, throw out the rest of the food. Mycotoxins are heat-resistant—so you can’t kill them through cooking—and they don’t rinse away with water.
Mild stomach upset from eating mold usually resolves on its own, she says. “However, symptoms like persistent nausea, vomiting, diarrhea, allergic reactions (such as hives or trouble breathing), or symptoms in someone with a compromised immune system should prompt a call to a doctor.”
Still, she says that if you feel sick after eating mold, foodborne bacteria may be to blame. “The more likely cause of illness in this scenario would be from bacterial infections that are growing along with the mold, since they thrive in similar environments and are much more likely to cause symptoms.” Food poisoning typically goes away on its own with rest and hydration. But no matter the cause, if you’ve eaten moldy food and have persistent or worsening symptoms—or you have a compromised immune system—it’s always best to seek medical advice.
However, there’s one symptom that requires immediate care. “If you are having difficulty breathing after eating mold, it is time to call a doctor or get to an emergency room,” Dr. Sandon says. This could mean you’ve ingested mycotoxins or are having an allergic reaction.
How to prevent mold on food
Kinga Krzeminska/Getty Images
The best way to avoid the potential risks of foodborne mold (and the aggravation of tossing out pricey groceries) is by preventing its growth in the first place.
“Store food properly,” Dr. Weiss advises. “Use airtight containers and refrigerate leftovers promptly.” The USDA recommends getting perishables into the fridge within two hours—and the sooner, the better. As for your fridge, keeping it cooled below 42 degrees Fahrenheit helps reduce mold growth, Dr. Sandon adds.
Dr. Weiss and Dr. Sandon say that it’s also important to:
Check expiration dates and inspect perishables like bread, berries, and soft cheese often.
Keep humidity low in the kitchen and pantry, as moisture promotes mold growth. “Aim for below 40% [humidity],” says Dr. Weiss.
Avoid washing fruits and vegetables until you are ready to eat them to reduce exposure to excess water and moisture.
Examine foods before you buy them—look out for signs of mold in jars, check produce stems, and avoid bruised produce.
It’s also a good idea to clean your fridge every few months to get rid of mold spores that might be lingering. Dr. Weiss says to:
Mix one tablespoon of baking soda into a quart of water, rinse the fridge interior, and dry it completely.
Scrub away any visible mold, which typically appears black.
Use three teaspoons of bleach mixed into a quart of water to wipe down the rubber seals of the fridge.
Keep your kitchen towels and sponges fresh, too. The USDA says that a musty smell is a sign these items are spreading mold around.
“Contamination is always a risk,” Dr. Sandon adds. “Picking up a piece of moldy fruit and then touching something else can contaminate other food.” In the same vein, fruit kept in a fruit bowl too long can spread mold quickly from one piece to another.
“It is important to avoid that cross-contamination,” she says. For instance, if you’re cutting moldy sections off of food, be careful to avoid contaminating the rest and wash your hands thoroughly before touching other food. “This also includes things like using a clean knife to spread your jam on your toast and avoiding putting a dirty knife—left on the counter or licked clean—back in the jam container.”
Ultimately, “when it doubt, throw it out,” Dr. Weiss advises. It’s impossible to tell the difference between harmless and dangerous mold (or detect if the mold is harboring bacteria), so if something doesn’t look or smell quite right, it’s best to avoid the risk altogether.
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