Can You Eat Mushrooms Raw: Health Risks, Nutrition & Safety

Can Humans Digest Raw Mushrooms?

Can You Eat Mushrooms Raw? The short answer is: It depends on the mushroom. However, even if you do, you would only be getting fiber and not much of the rest of the nutrition.

Chitin is a hard and sturdy material that gives insects, crabs, and other crawlies their protective shells. You can find chitin in some foods, such as seafood.

Chitin also makes up the cell walls of mushrooms, which are hard to break down as a consequence.

But can you digest it?

For a long time, people thought that chitin was indigestible for humans. But it turns out that we have some special enzymes in our bodies called chitinases. These enzymes help us fight off parasites that have chitin in them (Paoletti et al., 2007).

However, our chitinases are not very good at digesting chitin from food sources. They are more a defense mechanism than a digestive aid. That means that eating raw mushrooms won’t give you much nutrition. Raw mushrooms will just add some fiber to your diet, which can be good for your gut health.

You can think of chitin in mushrooms as similar to cellulose in plants. Both are types of fiber that can help you feel full and regulate your bowel movements.

If you want to lose weight or increase your fiber intake, then eating raw mushrooms can be a smart choice. But don’t expect to get much of the other benefits that mushrooms have to offer.

If you want to unlock the nutritional and medicinal potential of mushrooms, you need to cook them.

Cooking mushrooms helps break down their cell walls and release their valuable compounds.

These compounds include antioxidants, vitamins, minerals, and even some substances that can boost your immune system and fight cancer.

Are Mushrooms Healthier Raw or Cooked?

Mushrooms are not only delicious but also good for your health. They have antioxidants that can protect your cells from damage caused by free radicals. Mushrooms also have specific chemicals that can fight off cancer, increase our immunity, and help with different diseases.

But what happens when you cook mushrooms? Do they lose their antioxidants and health benefits?

That’s what researchers in this study (Choi et al., 2006) wanted to find out. They took raw shiitake mushrooms and heated them at different temperatures and times. Then they measured how much antioxidants they had left in them. They also tested how well they could fight off free radicals in a lab.

Researchers were surprised to see that cooking shiitake mushrooms actually increased their antioxidant levels and activity.

The hotter and longer we cooked them, the more antioxidants they had. For example, the shiitake mushrooms that were cooked at 121 °C for 30 minutes had almost twice as many antioxidants as the raw ones. They also did a better job at neutralizing free radicals. There was a strong link between the amount of antioxidants and the ability to fight off free radicals.

This is a consequence of chitin degradation. The overall level of antioxidants might dropped and be degraded due to heat but the chitin was degraded as well. Degradation of chitin at the end increased the bioavailability of antioxidants in mushrooms and this is what is important. It is not what we eat but what we absorb that matters.

This means that you don’t have to worry about losing the health benefits of mushrooms when you cook them. In fact, you may get even more benefits from them.

Cooking mushrooms can make them more tasty, tender, and aromatic, as well as more nutritious and protective.

Are All Mushrooms Safe To Be Consumed Raw?

Raw mushrooms can contain harmful pathogens and heat-sensitive toxins that can harm your health.

Raw mushrooms can cause damage to your red blood cells (Shibata et al., 2010), irritate your stomach and intestines, and trigger allergic reactions like skin rashes (Fang et al., 2017).

Not all mushrooms are the same. It varies from species to species.

Some species of mushrooms are poisonous, some have mind-altering properties, some are toxic when uncooked and some are safe in any form. However when we eat raw mushrooms there also might be a risk of contamination with dangerous pathogens if they are not handled properly.

So, how can you enjoy mushrooms without risking your health? The answer is simple: cook them well. Cooking mushrooms does more than just kill the bad stuff. It also breaks down the tough fungal tissues and releases nutrients.

But to get these benefits, you need to cook mushrooms properly. According to Choi et al., 2006, edible mushrooms should be heated to at least 140 ˚F for 3 to 4 hours, or better yet, over 180 ˚F, or best of all, above 200 ˚F. This will make them tender, digestible, and safe.

White Button, Cremini and Portobello.

There are over 2000 kinds of edible mushrooms, but only about 30 are grown or sold commercially. The most common one is the button mushroom.

Eating raw white button mushrooms is the same as eating raw cremini mushrooms or eating raw portobello mushrooms. There is no difference. All of these mushrooms are the exact same mushroom Agaricus bisporus. They are harvested at different stages of growth. White button mushrooms are the youngest and if left will become brown cremini mushrooms. Cremini is the middle-aged white button mushroom. Portobellos, which are much larger and brown are at the end stage of development and are fully matured.

But there is something you should know about button mushrooms.

Button mushrooms contain a substance called agaritine, which is a type of phenylhydrazine. Some studies on mice have suggested that agaritine might cause cancer and that eating mushrooms might be bad for your health.

Researchers did an experiment with special mice called lacI mice, or Big Blue mice (Shephard et al., 1995). These mice have a gene that can change color when it mutates, which makes it easy to measure the mutagenic potency of different substances. The researchers fed the mice three different diets for 15 weeks: (1) fresh mushrooms three times a week and normal food for the rest of the week; (2) freeze-dried mushrooms mixed with normal food; or (3) a mushroom extract with a high concentration of agaritine mixed with normal food.

Then they checked the DNA of different organs of the mice for changes in the color of the lacI gene. They called this the mutant frequency (MF).

Only the mushroom extract with a high dose of agaritine had a significant effect on the MF. It increased it by 100% in the kidney and 50% in the forestomach. The other two mushroom diets, with lower doses of agaritine, had no significant effect on the MF, except for a slight increase in the kidney. This means that agaritine was weakly genotoxic in vivo, meaning that it could cause mutations in living organisms. But it also means that there was no other genotoxic activity in the button mushroom, apart from agaritine.

The researchers used a formula to estimate the cancer risk of agaritine in mushrooms based on the MF data. They calculated that the average Swiss mushroom consumption of 4 g/day would result in a lifetime cumulative cancer risk of about two cases per 100,000 lives. This is for raw mushrooms however people usually don’t eat mushrooms raw.

So, what does this mean for you? It means that you don’t have to worry too much about eating button mushrooms raw. They are not very mutagenic.

But it also means that you should be careful about eating too much agaritine, which could be potentially found in high amounts in white mushroom extracts or supplements. Agaritine can cause mutations in DNA, especially in the kidney and stomach. This could increase your risk of cancer over time.

In a human study that followed 68,327 women and 44,664 men for up to 26 years (Lee et al., 2019), researchers measured mushroom consumption and risk of total and site-specific cancer. These people were all healthy and did not have cancer when the study started. They answered questions about how often they ate mushrooms and other foods, as well as their lifestyle and health habits. The researchers then tracked how many of them developed cancer over the years.

The people who ate five or more servings of mushrooms per week did not have a lower risk or higher risk of total cancer than the people who hardly ate any mushrooms. The same was true for 16 different types of cancer, such as breast, prostate, colon, and skin cancer. There was no evidence that mushrooms had any protective effect against these cancers.

Most people usually eat button mushrooms or other commercial types and do not consume functional mushrooms which are much more expensive and sold as supplements. Some of the functional mushrooms have proven anticancer benefits.

This study shows that in normal cooking with white button mushrooms, agaritine was not present in the amounts to increase cancer risk. We don’t need to worry if we eat button mushrooms in pasta or pizza or some other way that does not have adequate cooking time or temperature.

Cooking And Agaritine.

How much agaritine is actually in the mushrooms that we eat? And how does the amount change when we store or cook them?

These are some of the questions that researchers in this study tried to find out (Schulzová et al., 2002). The researchers analyzed fresh and processed samples of A. bitorquis and A. garicus hortensis mushrooms from different sources and found that the agaritine content varied widely depending on several factors. Here are some of their findings:

• Freshly harvested mushrooms from early flushes (the first batches of mushrooms that grow) had relatively high levels of agaritine, but samples from supermarkets had less agaritine.
• The agaritine content was not evenly distributed in the mushrooms. The highest amounts were found in the skin of the cap and in the gills, while the lowest were found in the stem.
• Storing the mushrooms in the refrigerator or freezer, or drying them, reduced the agaritine content significantly. The degree of reduction depended on the length and condition of storage and was usually between 20% and 75%.
• Cooking the mushrooms reduced the agaritine content but to different extents depending on the method.
• Boiling extracted around 50% of the agaritine into the broth within 5 minutes and degraded 20-25% of it in total. The rest of the agaritine was left in the liquid so making quick soups or sauces could be a problem. Prolonged boiling reduced the agaritine content even further (only around 10% left in the mushrooms after 1 hour). If you boil mushrooms throw away the water.
• Baking in the oven, like when making a pizza, reduced the agaritine content by about 23%.
• Frying in oil or butter or deep frying reduced it by 50%.
• Microwaving the mushrooms reduced the agaritine content to one-third of its original

Shiitake Mushrooms.

Shiitake mushrooms are a type of wood-grown mushrooms that are popular in Japanese and Chinese cuisine. They are the second most widely consumed edible mushrooms in the world, with an estimated annual production of over 10,000 tons.

But they are not just tasty and nutritious. They also have some amazing health benefits, such as lowering blood pressure, cholesterol, and cancer risk. That’s why Shiitake mushrooms are a big deal in traditional Asian medicine.

But before you rush to the nearest supermarket or Asian grocery store to buy some Shiitake mushrooms, there is something you should know.

Eating raw or undercooked Shiitake mushrooms can cause a very unpleasant skin reaction called flagellate dermatitis.

This is a rare condition, 2% of people are susceptible, which causes itchy, red, and blistered stripes on your skin, resembling whip marks. It usually appears 24 to 48 hours after eating the mushrooms and can last for days or weeks. The most common areas affected are the trunk, arms, legs, and neck, but sometimes the face or scalp can also be involved.

You might be wondering why this happens. Well, the culprit is a substance called lentinan, which is a type of polysaccharide found in Shiitake mushrooms. Lentinan has some anti-inflammatory and anti-tumor properties, which is why it is used as an adjuvant therapy for cancer patients in Japan. However, lentinan also stimulates the production of a chemical called IL-1, which causes inflammation and blood vessel dilation. This may explain why some people develop flagellate dermatitis after eating Shiitake mushrooms.

The treatment for flagellate dermatitis is mainly symptomatic. This means that you can use topical creams or ointments to soothe the itching and inflammation, such as corticosteroids or antihistamines. You can also take oral antihistamines or painkillers if needed.

However, the best way to prevent flagellate dermatitis is to avoid eating raw or undercooked Shiitake mushrooms altogether. Even if you cook them well, you may still have a chance of developing the condition if you are sensitive to lentinan. Therefore, it is advisable to stay away from Shiitake mushrooms if you have had flagellate dermatitis before or if you have a history of allergies or asthma.

False Morel Mushroom.

Some mushrooms contain chemicals that can cause cancer in animals and humans.

The first one is the false morel mushroom, also known as Gyromitra esculenta. This is a wild mushroom that looks like a brain or a sponge. It grows in temperate regions of Europe, Asia, and North America. Some people eat it as a delicacy, but they have to cook it very well to remove the toxins.

What are these toxins? Well, they are called hydrazine analogs, which means they have a similar structure to hydrazine, a highly reactive and explosive chemical used in rocket fuel. These hydrazine analogs can damage your liver and cause cancer.

Scientists have done experiments with hydrazine on mice and hamsters. Most of the animals developed tumors in their livers and other organs (Spencer & Kisby, 2021).

Hydrazine can also cause stomach cramps, diarrhea, and vomiting if consumed raw.

This toxin is destroyed by cooking, so you should always cook morels before eating them. Cooking also improves their flavor and texture, which are nutty, earthy, and meaty.

If you want to eat morels, you should also make sure they are clean and fresh. You can rinse them under cold water and soak them in salt water overnight to remove any dirt or insects. You should also avoid drinking alcohol while eating morels, as it may increase the toxic effects of hydrazine.

The second mushroom that contains hydrazine analogs is the common button mushroom, Agaricus bisporus. They contain small amounts of up to 0.04% of hydrazine analogs.

You should be careful when eating mushrooms that contain hydrazine analogs. You should avoid eating raw or undercooked false morel mushrooms at all costs. You should also cook button mushrooms well before eating them.

What Mushrooms Can You Eat Raw?

Not all mushrooms are created equal. Some mushrooms are poisonous, some are medicinal, and some are just plain delicious. How do you know which ones you can eat raw and which ones you need to cook? Let me give you some tips.

First of all, never eat a mushroom that you don’t know what it is. You might think you are picking a tasty treat, but you could end up with a nasty surprise. Some mushrooms are so toxic that they can kill you or make you very sick even after cooking them. For example, the death cap mushroom looks like an innocent white mushroom, but it contains a deadly toxin that can destroy your liver. So always be careful and do your research before eating any wild mushrooms.

Secondly, some mushrooms are edible but not very palatable when raw. They are either too tough, too bitter, or too bland to enjoy without cooking them.

For example, reishi mushrooms are a type of medicinal mushroom that has many health benefits, such as boosting your immune system and fighting inflammation. But they are also very hard and woody, so you can’t just bite into them. They need to be dried and ground into powder or extracted into tea or tincture.

Another example is honey mushrooms, which are also known as armillaria or bootlace mushrooms. They are a common edible mushroom that grows in clusters of wood. But they are also unsafe to eat raw because they can cause stomach cramps, nausea, and vomiting. You need to cook them well to get rid of the toxins and make them more digestible.

Other edible mushrooms that are better cooked than raw include boletus mushrooms, such as porcini or penny bun. These are prized gourmet mushrooms that have a rich and nutty flavor. But they are also very dense and chewy when raw, so you need to cook them to soften them and bring out their aroma.

Some mushrooms are safe and tasty to eat raw, but only if you prepare them properly. You need to wash them thoroughly and check them for any dirt, bugs, or mold before eating them raw.

There are several ways that contamination can be introduced to raw mushrooms like improperly sterilized compost or manure, contact with animals, or cross-contamination.

There’s naturally a greater risk of food poisoning or digestive issues when eating mushrooms raw. You also need to store them in a cool and dry place to prevent spoilage.

Some examples of mushrooms:

• Enoki mushrooms: These are thin and white mushrooms that have long stems and small caps. They have a mild and crunchy taste that goes well with salads and soups. These mushrooms are usually safe to eat raw, as they are cultivated in sterile conditions. There was one case in early 2023 of issued consumer advisory for enoki mushrooms potentially contaminated with listeria coming from China. Listeria-contaminated food can be life-threatening to pregnant women, newborns, the elderly, and people with weakened immune systems.
• Oyster mushrooms: These are fan-shaped mushrooms that have a soft and velvety texture. They have a subtle and sweet flavor that complements many dishes however they tend to have a slightly metallic flavor when uncooked. These mushrooms are also cultivated in clean environments and can be eaten raw.
• Porcini mushrooms: These are also known as cep or king bolete mushrooms. They are wild mushrooms that have a large brown cap and a thick stem. These mushrooms are not safe to eat raw, as they may contain harmful bacteria, parasites, or toxins. They should be cooked for at least 10 minutes to kill any potential pathogens and enhance their flavor.
• Shimeji mushrooms: These are also known as beech or clamshell mushrooms. They are small brown or white mushrooms that grow in clusters on wood. These mushrooms are also not safe to eat raw, as they may cause stomach upset or allergic reactions.

Finally, some mushrooms are technically edible when raw, but not very enjoyable. They may have an unpleasant texture or taste that makes them unappealing without cooking them. For example, king oyster mushrooms are large and thick mushrooms that have a mild and slightly sweet flavor. But they are also very dense and rubbery when raw, so they are not very fun to eat. You need to cook them to make them more tender and flavorful.

Remember, always identify your mushrooms before eating them, cook the ones that need cooking, wash the ones that can be eaten raw, and avoid the ones that are poisonous or unpalatable. Mushrooms are a wonderful food that can offer you many benefits if you eat them right.

FAQ

References:

1. Paoletti, M. G., Norberto, L., Damini, R., & Musumeci, S. (2007). Human gastric juice contains chitinase that can degrade chitin. Annals of nutrition & metabolism, 51(3), 244–251. https://doi.org/10.1159/000104144
2. Choi, Y., Lee, S., Chun, J., Lee, H., & Lee, J. (2006). Influence of heat treatment on the antioxidant activities and polyphenolic compounds of Shiitake (Lentinus edodes) mushroom. Food Chemistry, 99(2), 381–387. https://doi.org/10.1016/j.foodchem.2005.08.004
3. Shibata, T., Kudou, M., Hoshi, Y., Kudo, A., Nanashima, N., & Miyairi, K. (2010). Isolation and characterization of a novel two-component hemolysin, erylysin A and B, from an edible mushroom, Pleurotus eryngii. Toxicon, 56(8), 1436–1442. https://doi.org/10.1016/j.toxicon.2010.08.010
4. Fang, S., Bajoghli, A., & Bajoghli, M. (2017). Shiitake mushroom-induced flagellate dermatitis. Annals of allergy, asthma & immunology : official publication of the American College of Allergy, Asthma, & Immunology, 119(5), 462–463. https://doi.org/10.1016/j.anai.2017.08.007
5. Shephard, S. E., Gunz, D., & Schlatter, C. (1995). Genotoxicity of agaritine in the lacI transgenic mouse mutation assay: evaluation of the health risk of mushroom consumption. Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, 33(4), 257–264. https://doi.org/10.1016/0278-6915(94)00142-b
6. Lee, D. H., Yang, M., Keum, N., Giovannucci, E. L., Sun, Q., & Chavarro, J. E. (2019). Mushroom Consumption and Risk of Total and Site-Specific Cancer in Two Large U.S. Prospective Cohorts. Cancer prevention research (Philadelphia, Pa.), 12(8), 517–526. https://doi.org/10.1158/1940-6207.CAPR-19-0101
7. Moyano, E. G., & Pilar, L. M. (2021). Flagellate dermatitis secondary to intake shiitake mushrooms. Atencion primaria, 53(1), 102–103. https://doi.org/10.1016/j.aprim.2019.09.008
8. Spencer, P. S., & Kisby, G. E. (2021). Role of Hydrazine-Related Chemicals in Cancer and Neurodegenerative Disease. Chemical research in toxicology, 34(9), 1953–1969. https://doi.org/10.1021/acs.chemrestox.1c00150