Should You Toss Moldy Bread?

By Dr. Mercola

At some point or other, you may have looked in your cupboard and found unappetizing little moldy bits on your bread or hamburger buns. Like most people, your first reaction might be to throw it into the nearest garbage pail. Someone may even have admonished you, saying a few specks of mold on bread was “perfectly fine,” “nothing wrong with it,” or brought up the benefits of penicillin.

As NPR’s The Salt asks, “Is the furry green stuff a death knell for a baguette, or just a minor setback?” It turns out your initial reaction was probably the right one. Here’s the skinny: Experts on all things foodie agree that moldy bread slices should not serve as the tight ends on your sandwich. According to senior technical information specialist Marianne Gravely from the U.S. Department of Agriculture (USDA):

“We don't recommend cutting mold off of bread, because it's a soft food. With soft food, it's very easy for the roots (of the mold), or the tentacles, or whatever creepy word you want to use, to penetrate deeper into the food.”¹

Mold, for the record, is a type of microscopic fungi that makes its living on organic matter. By the time the lacy fingers of fungus have reached other areas of bread, it may be more than just mold. Other bacteria types may have set in, as well. A USDA food safety site says what you see may be the proverbial tip of the iceberg:

“Gray fur on forgotten bologna, fuzzy green dots on bread, white dust on Cheddar, coin-size velvety circles on fruits, and furry growth on the surface of jellies. When a food shows heavy mold growth, ‘root’ threads have invaded it deeply. In dangerous molds, poisonous substances are often contained in and around these threads. In some cases, toxins may have spread throughout the food.”²

The Problem With Moldy Bread

Mold on bread is called Rhizopus nigricans. Magnified a couple dozen times, vegetative filaments called mycelium and sporangia spores are visible. The Salt adds:

“[It has] visible spores on the surface and a network of microscopic roots that twist deep below that are often invisible to the naked eye. So, a mold's penetration into a piece of bread may be greater than a quick look-over suggests.”³

If you’re wondering if sliced bread might have fewer problems if just one end has detectable mold, there’s no guarantee the mold hasn’t spread; you just can’t see it. Other times you can see clearly that mold on one slice can indeed “infect” the one next to it. As tempting as it may be to save bread with just the tiniest green amoeba-looking fuzz decorating it (because you hate to throw out food), you should toss it.

People who eat moldy bread or other food can suffer from respiratory problems or have allergic reactions, and it may even be the explanation for other “mystery” illnesses. Even inhaling it (to see if it smells OK, for instance) can cause problems. In fact, its toxic potential necessitates putting it in a plastic bag and into a covered garbage can so kids or pets don’t get into it. That goes for jams, jellies and soft fruits, too. In case it’s not obvious, if lunch meat looks or smells a little “off,” pitch it.

Mold on Cheese and Other ‘Tough’ Foods

Certain “hard” foods can be placed in a different category; a spot of mold on them doesn’t necessarily place them in the “garbage” category. Examples include bell peppers, cabbage and carrots, hard cheeses like the Gorgonzola variety and even salami. The “tougher” surface may make mold more difficult to make its way deeper once it’s tainted the surface. Caught in a timely manner, cutting off the moldy spot may render the rest of the food safe and edible.

However, Gravely suggests cutting out a berth of about an inch on all sides of the moldy spot, using a clean knife. However, if the knife touches the mold, either wash it immediately or use a new knife.

Cheese, as suggested, is in a different category compared to bread. Not only are some cheeses containing mold safe to eat, a few varieties are actually created from mold and laced with it to enhance its flavor, such as blue cheese, Brie and Camembert, which many people consider desirable.

Here’s some advice on storing foods that may surprise you. When you're serving food, keep it covered to help prevent its exposure to mold spores that may be in your air.

Leftover foods from a jar, such as salsa, mayo or jams that you’ve placed in an attractive dish for a party should be put into a clean storage container as opposed to returning it to the same jar it came from. Also, refrigerate leftovers within two hours, and use them within three to four days so mold has much less of a chance to take hold.

Illnesses From Foodborne Molds Can Rival the Environmental Kind

Other foodborne molds often found on meat and poultry, however, are not only unhealthy, they can be downright toxic, rivaling the environmental kind. Food mold of this caliber is known as aspergillus, causing a group of illnesses responsible for mild to severe lung infections that can adversely affect your entire body.

Invasive aspergillosis, the most serious type of illness caused by aspergillus, enters your blood vessels, spreads throughout your body and can even manifest itself into a “fungal ball” in your lungs, causing an allergy resulting in fever, asthma, fatigue, weight loss and even a cough that produces blood.

There are upwards of 300,000 varieties of food fungi, and most of them, like the aforementioned mycelium filaments or “threads” on bread, can float through the air, in water and be carried by insects. The U.S. Food and Drug Administration (FDA) further explains:

“Unlike bacteria that are one-celled, molds are made of many cells and can sometimes be seen with the naked eye. Under a microscope, they look like skinny mushrooms. In many molds, the body consists of:

The spores give mold the color you see. When airborne, the spores spread the mold from place to place like dandelion seeds blowing across a meadow.

Molds have branches and roots that are like very thin threads. The roots may be difficult to see when the mold is growing on food and may be very deep in the food. Foods that are moldy may also have invisible bacteria growing along with the mold.”⁴

It Doesn’t Have to Be ‘Black Mold’ — Mold on Food Can Make You Sick, Too

Some people are more sensitive to mold than others. Exposure can bring about symptoms ranging from itchy, watery eyes and a stuffy nose to skin irritation such as hives, and wheezing. The World Health Organization issued directives⁵ regarding illnesses caused by exposure to environmental molds.

In occupations in which microscopic dust or silica may be floating around, or when farmers’ hay gets wet and moldy, people in the vicinity may experience shortness of breath or fever. For those with chronic lung illnesses like obstructive lung disease, mold may initiate lung infections.

Unfortunately, while these problems may sound like harmless irritants, sometimes they’re serious enough that they segue into more critical illnesses and can even be life threatening. But here’s the kicker: Foodborne molds can be just as bad.

Molds produced by nuts and grains include mycotoxins. One, called aflatoxin, has undergone extensive study. It can be found in “corn and corn products, peanuts and peanut products, cottonseed, milk, and tree nuts such as Brazil nuts, pecans, pistachio nuts and walnuts,” the FDA⁶ says.

If you’re sensitive to mold, environmental or otherwise, you may be more susceptible to molds on foods. Some foods at high risk of mold contamination should be avoided as they can add to your body's toxic burden so much your body can’t keep up, your ability to detoxify is compromised and your immune system suffers. The foods include:

How to Avoid Foodborne Toxins Derived From Sketchy Food

In terms of keeping your eyes open and keeping abreast of new information regarding your health, the phrase “let the buyer beware” may be the most effective way to save you and your family from potential misery from eating moldy food. For instance, check produce sold in plastic containers before making a purchase. The Salt advises:

“If shoppers discover a couple of moldy strawberries once at home, no need to jettison the entire bunch — just wash the other strawberries well and make sure the mold hasn't spread.”⁷

What makes it difficult is that mold is not always obvious, but here’s some good news to help maximize freshness and quality: There’s an app for that. The U.S. Department of Health and Human Services provides the FoodKeeper App,⁸ which is designed to inform consumers regarding the best way to store food and beverages.

Developed by the USDA’s Food Safety and Inspection Service in conjunction with Cornell University and the Food Marketing Institute, the premise for using the app is to keep food fresh longer than if it wasn’t stored properly. The app is available for both Android⁹ and Apple,¹⁰ and the food categories listed are extensive. Under the commercial bread products heading, for instance, the app notes that for optimal freshness and quality, pan breads, flat breads, rolls and buns should be eaten within:

• 14 to 18 days if stored in your pantry
• Two to three weeks if refrigerated after opening
• Three to five months if frozen

Additionally, let common sense be your guide, especially since the “sell by” date may not really have anything to do with the safety of food. Cleaning your refrigerator every few months helps keep problems at a minimum and, remember, as Gravely describes mold spores:

“They're pretty clever and adaptable. They prefer moist environments and warm temperatures, but they can grow in the refrigerator, and they can grow in sweet things or salty things … Food in your kitchen is completely within your control.”¹¹