What Happens if You Eat Moldy Bread

If you eat moldy bread, you may eventually suffer gastrointestinal discomfort. However, it's usually harmless. Keep reading to learn more.

Reviewed and approved by the nutritionist Maria Patricia Pinero Corredor.

Written by Daniela Echeverri Castro

Last update: 22 August, 2024

Chances are, at some point, you’ve had an unpleasant experience with moldy bread. Maybe you were enjoying a delicious sandwich when suddenly you took a bite of a dark spore stain.

You may also have found yourself in a situation where you checked the cupboard and saw that the bread you had stored had parts with small fungi that varied between black and greenish tones. When this happens, you wonder if you can remove the moldy pieces and eat the parts that seem to be in good condition.

How should you proceed? Can you get sick if you accidentally ingest it? To help you answer these questions, we’ll explain below what happens if you eat it and whether or not you can cut the affected portions. As a bonus, here are some tips for keeping bread fresh.

What happens if you accidentally eat moldy bread?

Don’t panic! Although there is a chance of gastrointestinal discomfort, it’s unlikely that you’ll experience food poisoning after eating a piece of moldy bread. If you’ve just realized that you’ve mistakenly ingested the damaged food, keep calm and pay attention to any symptoms that may arise.

As long as your immune system is healthy, you’re unlikely to suffer any consequences, other than a feeling of disgust at the time. However, you should watch out for symptoms such as nausea, diarrhea, vomiting, fever, or breathing difficulties.

In some people, certain molds that are present in bread can cause allergic reactions that can be life-threatening and health-threatening. If so, seeking immediate medical attention is crucial. Whether this is mild or severe, immediate or delayed, depends largely on the type of mold.

Ocassionally, you may experience nausea or stomach pain after eating moldy bread. However, most likely, nothing will happen, as most of the molds in this food are harmless. You can get sick if you have an allergic reaction to a particular mold.

Why does mold grow on bread?

Before we go any further, let’s give you some context. The mold you see with the naked eye on bread is a fungal growth. Those furry-looking parts that usually appear in white, yellow, greenish, gray, or black tones are colonies of spores that have the function of reproducing the fungus.

The spores themselves are very tiny, almost microscopic, and are transported through the air without being noticed by the naked eye. Therefore, they’re capable of reaching surfaces that meet the necessary conditions for them to grow and develop. In this case, bread.

When bread is left out in the open – whether during the production process, sale, or handling at home – the spores settle on it. Over time, especially if the temperature is warm, they reproduce and give rise to the appearance of mold.

This whole process is favored if the food’s storage or wrapping provides humidity and heat. The ingredients used to prepare the bread are also a factor.

Different types of fungi grow on bread, which affects its appearance and color. The most common are the following:

• Penicillium: This is a type of mold that is harmless to most people and is the source of the famous antibiotic that is commonly used penicillin. However, some people may be allergic to it. At first, it appears white, but later it takes on a blue-green or olive-gray color.
• Rhizopus Stolonifer: This is popularly known as black mold on bread. It produces toxins that are harmful in patients with weak immune systems.
• Cladosporium: This is one of the most common indoor fungi. Its color varies from dark green to black. It’s usually the most irritating for people with allergies.
• Aspergillus: These are commonly found in foods such as fruits and bread. They have a velvety appearance and are whitish with bluish, grayish-green, and yellowish tones. They produce mycotoxins that cause stomach discomfort. In addition, they alter the intestinal microbiota.

Can you cut the moldy part of the bread and eat the rest?

You may notice the mold stains only in some small parts of the bread or only in several slices, while the rest, to the naked eye, looks to be in good condition. Therefore, you may deduce that it’s safe to cut off the affected pieces and consume the rest. But is this true? Is this practice actually safe?

The answer is a resounding no. You must take into account that this is a moist and porous food that meets all the conditions for the growth of the fungus. And although these aren’t visible on the entire piece, it’s most likely that their microscopic roots are already spreading throughout the product.

It can also be contaminated simultaneously with bacteria and several types of fungi. While many are harmless, there’s no way to confirm if they are.

The risk of this is a possible exposure to mycotoxins that can cause everything from digestive symptoms (nausea, vomiting, abdominal pain, and diarrhea) to more serious reactions, such as breathing difficulties, immune weakness, and kidney and liver problems, among others.

After eating moldy bread, how long does it take to get sick?

You may or may not get sick after eating moldy bread. This depends largely on the type of mold in question and the amount ingested but mostly on the level of response of your immune system.

If you’re susceptible to allergies or have a history of mold allergy, you’re more likely to suffer complications. Now, there’s no exact data to determine how soon you’ll experience symptoms. Sometimes it’s instantaneous, but in other cases, reactions are delayed.

The most important thing is to be vigilant after eating the moldy food. If you experience stomach pain, nausea, vomiting, or diarrhea, among other warning signs, it’s best to seek medical attention. Some people at higher risk of getting sick are the following:

• Young children.
• Pregnant women.
• Patients with diabetes.
• Adults over 65 years of age.
• People with compromised immune systems (patients with lung disease, heart disease, cancer, and human immunodeficiency virus – HIV).

You should consider that some of the mycotoxins in food molds can alter the environment of the gut microbiota. By destroying the beneficial bacteria in the gut, they raise the risk of chronic diseases. However, this situation usually occurs with large or prolonged intakes.

How to proceed if food is moldy

Some molds in food are safe to eat, such as blue cheese. In other hard vegetables, such as carrots, bell peppers, and cabbage, it’s more difficult for these microorganisms to spread, so the risk is low, and the damaged part can be removed.

However, when it comes to foods such as breads -which are soft, moist, and porous- the most sensible thing to do is to discard the whole product. The same applies to products such as yogurt, sausages, butters, jellies, and soft fruits and vegetables (cucumbers, tomatoes, peaches, etc.).

According to dietitian Lillian Craggs-Dino, via the Cleveland Clinic, the safety of other foods depends on the situation. For example, if molds are on the peel, they’re unlikely to be on the fruit unless they show obvious signs when peeled, such as dark spots or odor.

How long does fresh bread last?

The durability of bread changes depending on whether it is homemade or industrially baked. As a general rule, homemade or artisanal bread has a shelf life of three to four days in the pantry and two to three months in the freezer.

Meanwhile, commercial bread lasts up to two weeks at room temperature or in the refrigerator and up to five months in the freezer. This is because they contain chemical p reservatives such as calcium propionate and sorbic acid, which prevent fungal growth.

How to keep bread fresh for longer?

Several factors increase the likelihood that bread will develop fungus. The method of preparation, the ingredients added, and the type of preservation are some of the most relevant. Even so, if you want to keep it fresh for longer, you can put the following recommendations into practice.

Let bread cool before storing

Remember that mold grows more easily in warm, humid environments. When you store bread very hot, the steam promotes these conditions. Therefore, before placing it in the pantry, on the counter, or in packaging, be sure to let it cool.

Keep bread covered

Although they’re not visible, mold spores are in the air. One way to reduce their contact with bread is to cover it before consumption. Cloth bags and bread bags are considered the best options, followed by paper bags.

Store in a cool, dry place

Once you store the bread in the bag or breadbox, find a kitchen space that’s cool, dry, and, preferably, dark. Make sure there are no heat-generating appliances nearby. Also, the cabinet should be clean and free of moisture.

Opt for freezing

While refrigerating bread is a good option to stop the growth of molds, it’s better to freeze it. Why? This method of preservation doesn’t alter the texture as much and prolongs the shelf life of the food. You only have to keep the slices cut so that you can take them out and heat portions as required.

Fun fact: Gluten-free bread is more susceptible to mold growth. That’s why it’s often distributed frozen.

Choose sourdough bread

Right now, sourdough bread is one of the most recommended options for enjoying this fresh, preservative-free food. Its durability is greater due to the natural enzymes it contains, in addition to the fat.

In fact, some recipes of this variety contain lactic acid bacteria (probiotics) that, by producing acids, prevent the growth of mold.

Add spices or vinegar to your homemade recipe

Some homemade bread recipes propose the incorporation of certain spices, such as cinnamon and cloves, or apple cider vinegar, as a trick to preserve and prevent the proliferation of fungi. The drawback? They change the flavor and aroma of the final product. But if this isn’t a problem for you, it is a good option.

What to do with stale bread?

Ultimately, if the bread is stale and not yet moldy, you can use it in other preparations. A good idea is to toast it and pass it through a food processor to make breadcrumbs. This can be used in batter, for example.

You can also toast the bread, cut it into cubes, and add it to salad recipes. If you prefer, mix it with a little olive oil, bake it in the oven, and then sprinkle it with spices. You’ll love it!

What to remember?

If you realize you’ve accidentally eaten moldy bread, stay calm; most of the time, it’s harmless. Still, watch for symptoms such as nausea, vomiting, diarrhea, stomach upset, or breathing difficulties, which may alert you to an allergic reaction to mold.

If so, don’t hesitate to see a doctor as soon as possible. Keep in mind that inhalation of the spores is also problematic, especially if there’s a history of mold allergy. Avoid sniffing the bread closely if you notice visible stains.

Also, whenever you see mold on parts of the food, even if it doesn’t cover the entire food, be sure to discard it. Due to its porous and moist characteristics, bread meets the right conditions for fungi to proliferate, even unnoticed.

If you want to prolong its shelf life, store it in a cool, dark place (if you’re going to eat it in the next two or three days) or put it in the freezer (if you want to eat it up to weeks later).