Is It Safe to Eat Moldy Bread or Cheese?

Moldy Bread

Story at-a-glance -

  • Mold on hard foods (hard cheese, firm vegetables) can be cut off (with an inch around it), and the food safely consumed
  • Mold on soft foods (bread, fruit, and soft cheese and vegetables) has likely permeated through the food, so it should be discarded
  • While some mold is harmless, others can cause allergies, respiratory problems, or may produce cancer-causing substances called mycotoxins

By Dr. Mercola

You take a block of cheese out of your refrigerator and notice fuzzy spots of white or green mold. Should you toss it or simply cut the mold off? What about mold that appears on other foods, like strawberries or bread?

The "rules" about when it's safe to eat moldy food or not vary depending on the type of food. Generally speaking, if the food is hard, such as a brick of cheddar cheese or a carrot, you can cut off the moldy section (plus about one inch around it) and use the rest.

For softer foods, they should be discarded when mold is spotted because, the fact of the matter is, mold can be quite dangerous, and its roots can easily permeate soft foods, contaminating areas that appear to be mold-free. Let me explain…

What Is Mold?

Mold is a type of microscopic fungi that lives on organic matter. It's estimated that there are 300,000 or more different species of fungi, most of which are thread-like and produce spores that can be easily spread in air or water (or by insects). In many cases, mold will consist of three primary parts:1

  • Root threads (which can spread throughout your food and may not be visible with your naked eye)
  • Stalks rising above the food
  • Spores at the end of the stalks (the spores give the mold its color)

Some mold is perfectly safe to eat and, in some cases, even desirable (the classic example would be cheeses made with mold, such as blue, Brie, Camembert, and Gorgonzola). Other molds can be quite toxic and may produce allergic reactions and respiratory problems, or produce poisonous substances called mycotoxins.

Aspergillus mold, for instance, which is most often found on meat and poultry (as well as environmentally), can cause an infection called aspergillosis,2 which is actually a group of illnesses ranging from mild to severe lung infections, or even whole-body infections.

The most serious type of aspergillosis is invasive aspergillosis, which is when the mold invades your blood vessels and the spreads to the rest of your body. Aspergillus allergy can result in fever, productive cough, and worsening asthma.

With aspergillosis, you can actually grow a "fungal ball" in your lungs, a tangled ball of fungal fiber called aspergilloma. Aspergilloma can lead to coughing up blood (hemoptysis), wheezing, shortness of breath, fatigue, and weight loss. Other common foodborne molds include:


Grains and Nuts Are Common Sources of Toxic Mycotoxins

One of the greatest concerns regarding mold in food is the mycotoxins that some varieties produce. One of the most researched mycotoxins is aflatoxin, a cancer-causing poison. According to the US Food and Drug Administration (FDA):3

"In the United States, aflatoxins have been identified in corn and corn products, peanuts and peanut products, cottonseed, milk, and tree nuts such as Brazil nuts, pecans, pistachio nuts, and walnuts. Other grains and nuts are susceptible but less prone to contamination."

Aflatoxin is said to be the most carcinogenic naturally occurring substance known, and it is known to cause liver cancer and immune suppression in humans. While the US FDA and the US Department of Agriculture (USDA) monitor peanuts and field corn for aflatoxin at high levels, there is concern about long-term exposure to low levels of this common mold-related toxin.

According to the Food and Agriculture Organization (FAO) of the United Nations, about 25 percent of the world's food crops are affected by mycotoxins, including aflatoxin.4 As noted by the USDA:5

"Many countries try to limit exposure to aflatoxin by regulating and monitoring its presence on commodities intended for use as food and feed.

The prevention of aflatoxin is one of the most challenging toxicology issues of present time… Aflatoxins are considered unavoidable contaminants of food and feed, even where good manufacturing practices have been followed."

Unfortunately, this is one type of mold toxin that you can't detect by examining your food. There are some tips you can use to minimize this risk, however. In the case of pistachios, for instance, be sure the pistachios you eat come from a reliable supplier, which dries the nuts immediately after harvest to minimize decay.

Some California pistachio farmers are also using spores of a beneficial fungus to displace the fungi that produce aflatoxin. This strategy has been found to reduce aflatoxin by up to 45 percent, without the use of chemicals.6 You can further reduce your risk by:

  • Choosing in-shell pistachios (shelled pistachios are much more likely to be contaminated with aflatoxin)
  • Avoiding dyed pistachios, which may cover up staining
  • Avoiding eating pistachios that have a sour taste or signs of mold, excessive moisture, or insect damage
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Mold on Food: What to Toss, What to Keep

Mold that's visible may appear to exist in contained areas on your food – a gray furry spot here or a few green dots there. However, beneath this visible mold are likely deep roots that may have invaded the rest of the food. In cases where the mold is dangerous, its toxic elements may be contained not only in these threads but also throughout the food.

For this reason, if you see mold anywhere on a soft, easily penetrable food, you should discard it. You may also need to toss nearby foods that may have touched the moldy area, as mold can spread quickly and easily, especially in produce. Moldy foods that you throw away should be put into a small paper or plastic bags so the mold cannot escape.

Do not attempt to sniff the moldy food to see if it's spoiled, as this can introduce mold spores into your respiratory tract. In the case of harder foods, it's acceptable to cut off the moldy spot and about one inch around it (to ensure you've removed any roots).

When doing this, be sure the knife does not touch the mold and contaminate the area you are cutting. The USDA has compiled the chart below to help you determine when a moldy food should be kept or discarded.7

Luncheon meats, bacon, or hot dogs Discard Foods with high moisture content can be contaminated below the surface. Moldy foods may also have bacteria growing along with the mold.
Hard salami and dry-cured country hams Use. Scrub mold off surface. It is normal for these shelf-stable products to have surface mold.
Cooked leftover meat and poultry Discard Foods with high moisture content can be contaminated below the surface. Moldy foods may also have bacteria growing along with the mold.
Cooked casseroles Discard Foods with high moisture content can be contaminated below the surface. Moldy foods may also have bacteria growing along with the mold.
Cooked grain and pasta Discard Foods with high moisture content can be contaminated below the surface. Moldy foods may also have bacteria growing along with the mold.
Hard cheese
(not cheese where mold is part of the processing)
Use. Cut off at least 1 inch around and below the mold spot (keep the knife out of the mold itself so it will not cross-contaminate other parts of the cheese). After trimming off the mold, re-cover the cheese in fresh wrap. Mold generally cannot penetrate deep into the product.
Cheese made with mold
(such as Roquefort, blue, Gorgonzola, Stilton, Brie, and Camembert)
Discard soft cheeses such as Brie and Camembert if they contain molds that are not a part of the manufacturing process. If surface mold is on hard cheeses such as Gorgonzola and Stilton, cut off mold at least 1 inch around and below the mold spot and handle like hard cheese (above). Molds that are not a part of the manufacturing process can be dangerous.
Soft cheese
(such as cottage, cream cheese, Neufchatel, chevre, Bel Paese, etc.) Crumbled, shredded, and sliced cheeses (all types)
Discard Foods with high moisture content can be contaminated below the surface. Shredded, sliced, or crumbled cheese can be contaminated by the cutting instrument. Moldy soft cheese can also have bacteria growing along with the mold.
Yogurt and sour cream Discard Foods with high moisture content can be contaminated below the surface. Moldy foods may also have bacteria growing along with the mold.
Jams and jellies Discard The mold could be producing a mycotoxin. Microbiologists recommend against scooping out the mold and using the remaining condiment.
Fruits and vegetables, FIRM
(such as cabbage, bell peppers, carrots, etc.)
Use. Cut off at least 1 inch around and below the mold spot (keep the knife out of the mold itself so it will not cross-contaminate other parts of the produce). Small mold spots can be cut off FIRM fruits and vegetables with low moisture content. It's difficult for mold to penetrate dense foods.
Fruits and vegetables, SOFT
(such as cucumbers, peaches, tomatoes, etc.)
Discard SOFT fruits and vegetables with high moisture content can be contaminated below the surface.
Bread and baked goods Discard Porous foods can be contaminated below the surface.
Peanut butter, legumes, and nuts Discard Foods processed without preservatives are at high risk for mold.

Proper Food Storage Can Help Prevent Spoiled Food

After you've removed a moldy item from your refrigerator, be sure to clean the area where it was stored (you can find tips on how to best clean your refrigerator here). Otherwise, you may simply re-contaminate the next food item you put in. Next, you can drastically reduce food spoilage by learning the basics of proper food storage. In your fridge, for instance, meat, poultry, fish, and leftovers should be stored on the bottom shelf, where temperatures are cold and stable.

On the other hand, the fridge door is the warmest part of the fridge and temperatures can fluctuate significantly, so use it only to store condiments and butter. Citrus fruits can last up to two weeks right on the counter, while garlic and onions need to be stored in a dark, cool pantry, where they will stay fresh for up to four months. The life of leafy greens can be extended by as much as three extra days if you don't wash them before putting them in your fridge. Also keep in mind that apples, pears, and bananas release natural ripening agents that will hasten the demise of any other produce placed in their vicinity. For more details, I've listed 27 tips to make your groceries last longer here, which include many tips to keep mold growth at bay:

  1. Store onions in old pantyhose to keep them fresh for up to eight months (tie a knot in between each one to keep them separate).
  2. Chop dry green onions and store them in an empty plastic water bottle. Put the bottle in the freezer and sprinkle out what you need when you're cooking.
  3. When storing potatoes, keep them away from onions (this will make them spoil faster). Storing them with apples will help keep the potatoes from sprouting.
  4. Store salad greens in a bowl covered with plastic wrap, and add a paper towel to help absorb moisture. A salad spinner will also help remove excess moisture -- a key culprit in wilting leaves -- from your greens.
  5. Mushrooms should be stored in a paper bag in a cool dry place, or in the fridge. Avoid storing mushrooms in plastic, as any trapped moisture will cause them to spoil.

How to Reduce Mold Growth on Your Food

There are additional steps you can take to protect your food from mold growth. When you're serving food, it's important to keep it covered, for instance, as this helps prevent exposure to mold spores that may be in your air. When you use jarred foods, you should also put any leftovers into a clean storage container (don't store it right in the same jar). It's always important to refrigerate leftovers promptly (within two hours or less) and use up leftovers within three to four days (this way mold won't have a chance to grow).8

If you've got containers of food sitting in your fridge for long enough to get moldy, you're probably not planning out your meals as efficiently as possible. Before you go food shopping, make a meal plan for the week. Do a thorough check of what you already have on hand so you don't let good food go bad, and have your meals planned so the fresh foods you buy get eaten in a timely manner (and while they're still fresh).

Have You Considered Mold in Your Home?

While it's important to reduce and minimize exposure to mold in your food, it's also wise to consider other sources of mold exposure, including that in your home. As many as 40 percent of all American schools and at least 25 percent or more of all homes are believed to be affected by mold and microbial growth due to water intrusion.

According to mold expert Dr. Jack Thrasher, the prevalence of mold in America is so great he refers to it as pandemic. A musty, mildew odor is a tip-off that you need to check your home for any visible signs of mold. Unexplained health problems, including frequent headaches, chronic fatigue, skin rashes, allergies, chronic sinusitis and more may also be due to mold exposure. For more information, please view my interview with Dr. Thrasher below, in which he discusses the health effects of toxic molds and bacteria in your home, as well as his recommendations for remediation.

Total Video Length: 1:13:43

Download Interview Transcript

+ Sources and References