Did you know some edible mushrooms can still make you sick?

Even ‘edible’ mushrooms need to be handled properly to prevent illness.

True morels are hollow inside and are attached to the mushroom stem at the base of the cap.

True morels are hollow inside and are attached to the mushroom stem at the base of the cap.

Michiganders are dreaming of wild mushroom harvesting with the warming temperatures, especially the coveted spring morels, but are you aware that some edible mushrooms can still make you sick? Of the 2,500 large, fleshy mushroom species in Michigan, only 60-100 of them are generally regarded as safe to eat. That sentence should make two questions come to mind- why 60-100 and not an exact number, and what does “generally regarded as safe” mean?

What does ‘generally regarded as safe’ mean?

 “Generally” indicates that in most cases, the food is consumed without ill effects if it was handled and cooked properly. However, there are always exceptions to rules and sometimes mushroom experts disagree on the likelihood of a particular mushroom causing illness. For example, true morels (Morchella spp.) are generally safe to eat as long as they have been cooked thoroughly. However, eating raw morels can cause gastric upset. Also, some individuals have allergies or intolerances for certain types of morels. For these reasons, morels are considered generally safe to eat but should be consumed with caution the first time.

Other mushrooms that are generally safe to eat can cause adverse reactions too. An example is the “chicken of the woods” or sulphur shelf (Letiporus sulphureus). The edibility of this mushroom depends on what type of tree it is growing on. Typically, this species, if gathered from hardwood trees is edible, but those gathered from conifers or locusts are frequently toxic. Another example is the Coprinus genus, also known as “inky caps.” While many species in this family of mushrooms are choice and edible, some of them react poorly when consumed with alcohol. Coprine, while not technically a toxin, and not a serious threat to health, interferes with how the human body deals with alcohol (which is a toxin), causing unpleasant illness. This sudden onset of illness can also cause people to think they have mistakenly eaten something poisonous. When eating Coprinus mushrooms, avoid alcohol two to three days before and after consumption of the mushroom.

Poisonous mushrooms

In Michigan, there are 50 species of large, fleshy mushroom known to be toxic to humans. Levels of toxicity vary between species and range from “deadly poisonous,” to “occasional gastric distress.” Several of the deadly species, especially those in the Amanita family, are extremely dangerous because symptoms don’t develop until six to 36 hours after ingestion, which is too late for the only antidote – a stomach pump. Another group of poisonous mushrooms to be aware of this spring are the false morels. They include Gyromitra esculenta (also called beefsteak), Verpa conica, and Verpa bohemica. These are commonly mistaken for true morels because they look similar and grow next to morels. They can, however, have deadly results. Although some people have eaten these mushrooms without illness, they often cause vomiting, diarrhea, and cramps, and can cause kidney failure and death. The amount of poison can vary from mushroom to mushroom which leads people to think that if they ate one and had no adverse effects, they can eat others, which is not true.

Each person’s body reacts differently to mushroom toxins. For example, you could eat beefsteak mushrooms 10 times and be fine, but become seriously ill or even die the eleventh time you ate them because those particular the mushrooms contained enough toxin to cause illness or death. Even breathing the vapors from boiling such mushrooms can cause illness. Gyromitra species are known to carry a carcinogen, which can also build up in the body over time. Poisonous mushrooms may also cause allergic-type reactions, or cause hallucinogenic reactions.

In addition to the 50 large toxic species, there are many smaller mushrooms that cause illness, often referred to as “little brown mushrooms.” They are incredibly difficult to identify properly unless you are an expert in the field of mushrooms. Many poisonings from these types of mushrooms occur when people are purposely seeking out hallucinogenic, or “magic” mushrooms. These mushrooms are not considered to be food, and most poisonings occur from misidentification or accidental ingestion by children. More extensive information on mushroom toxins specific to Michigan can be found in the guide, “Don’t Pick Poison.”

Identifying mushrooms

So, how do you eat delicious wild mushrooms and not get sick? There are a few rules of thumb when it comes to wild mushrooms. First and foremost, never eat any mushroom unless you are positive about its identification. Learn how to identify mushrooms, their parts, and the dangerous look-alikes. Guidebooks are helpful, but keep in mind that some people regard one mushroom as “edible” while others say to avoid them due to one or more of the properties discussed above. Cross-compare several guidebooks before making a decision. Consider taking a class or workshop that specifically teaches about wild mushrooms. The Midwest American Mycological Information (MAMI) group have study guides as well as several classes offered every year.

When it comes to the spring morels, look for mushrooms that have pitted caps, as opposed to the folds or wrinkles of the dangerous look-alikes. True morels are hollow inside, so always cut them open and make sure. Finally, morels are attached to the mushroom stem at the base of the cap. 

Always cook wild mushrooms, and pay attention to special warnings like whether or not they may react with alcohol. Never re-use the cooking water as it will contain toxins from the mushroom (unless it is a mushroom that is specifically okay to use as soup stock). Avoid breathing vapors while cooking mushrooms like morels. It is also good practice to only eat a small amount of a new mushroom and only consume one new species at a time. This way, if you do have an adverse reaction, you’ll know which mushroom it was. Saving a small amount of the mushroom in your fridge may also be helpful if you have to go to the hospital.

Mushroom hunting can be fun, nutritious, and a good way to get physical activity, but it can also be dangerous. Michigan State University Extension recommends studying up on mushroom identification before going out and picking this year. If you have any doubts, don’t eat it.

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