Can Moldy Sourdough Bread Make You Sick (And How Long Does It Really Last Before Spoiling)?

You're in the mood for a sourdough sandwich, so you grab the loaf in your bread box. That's when you see it: mold. Though it's frustrating to see signs of mold on sourdough bread (especially on a loaf you recently bought or baked yourself), mold development on baked products is normal. However, you shouldn't just ignore mold because it can lead to health issues. (In fact, you should be on the lookout for signs of mold to understand the meaning behind white spots on bread and other potential mold-related red flags.)

Eating or inhaling mold can cause respiratory or gastrointestinal problems. Plus, some molds can be toxic. It's wise to discard moldy bread immediately, since what looks like surface mold could actually extend to the interior of the loaf. As nutritionist Lorene Sauro explains (via Food and Wine), "If you can see some mold spots, many more mold spores are present and not visible to the naked eye."

This doesn't mean that all food mold is bad, of course. Sometimes, mold is used to make foods. Take gorgonzola cheese, for instance. Its creation depends on a type of fungus called penicillium glaucum. In this case, the moldiness becomes part of the cheese and is okay to eat with the exception of people who have compromised immunity or are sensitive to penicillium glaucum. People with a histamine intolerance should avoid these types of aged cheeses as well. In constrast, the mold that grows on sourdough bread results from a mold strain that isn't considered healthy to ingest. That's why it's better to toss your sourdough bread once it begins to mold.

The positive side of all this mold talk is that your sourdough bread is probably going to outlast the other kinds of bread in your house, so you can enjoy it for a while. That's because the fermentation process involved in making genuine sourdough bread makes the bread more resistant to mold. Consequently, make sure you're buying sourdough bread that actually uses a traditional sourdough starter rather than baker's yeast.

You can take other measures to reduce your chances of having to discard your sourdough bread because of mold, including keeping the bread in a container that limits the loaf's air exposure or refrigerating or freezing the loaf. You may also want to keep your home's humidity levels to a minimum to avoid excessive ambient moisture.

While it may make you sick to discard your sourdough bread because of mold, you'll be less likely to get actually sick from eating it. Additionally, pay attention to the "best-if-used-by" date on the packaging, particularly if you want to avoid accidentally eating expired bread. Generally speaking, sourdough bread stays fresh for up to five days.

And if you somehow end up eating moldy sourdough bread, just stop eating it as soon as you're aware. You'll probably be okay, according to dietitian Lillian Craggs-Dino (via Cleveland Clinic). Just take her advice to "make sure you don't have any symptoms for the rest of that day" and get medical treatment if you experience severe symptoms like fever, loose stools, or breathing difficulties.