Can you eat mushrooms raw?

In this brief guide, we will answer the question, “Can you eat mushrooms raw?”. We will further elaborate on the health benefits and dangers of eating raw mushrooms. 

Can you eat mushrooms raw?

Yes, you can eat mushrooms raw. But, not all varieties of mushrooms can be eaten raw. 

All fresh Canadian mushrooms bought from a supermarket are safe to consume raw. Enokis, portabellas, white button mushrooms, cremini and other brown mushrooms can be added to salads as it is. 

On the contrary, the more exotic mushrooms that include shiitake, oyster and king oyster are best to eat when cooked as they are more palatable when cooked.

It is all about the taste and texture. Some people believe that raw mushrooms taste good and others don’t. Also, some varieties of raw mushrooms are very hard to digest due to their tough cell walls that predominantly consist of chitin.

Another important concern is that some raw mushrooms, for instance, the Agaricus genus contains a high level of agaritine, harmful pathogens and heat-susceptible toxins which can pose various health risks including red blood cell deterioration, allergies, for instance, skin rashes and intestinal irritation. 

So, you may have to skip this type if you are worried about this naturally occurring toxin.

What are mushrooms?

Mushrooms are heterotrophic eukaryotic organisms classified in the kingdom of Fungi. Recent estimates based on high-throughput sequencing methods suggest that there are as many as 5.1 million fungal species worldwide (1).

Mushrooms are fungi forming fruit bodies (sporocarps) that are visible to the naked eye. The term mushroom relates to the fleshy fruit body of the macrofungi that can be edible or inedible regardless of its shape and kind (1). Many different varieties of mushrooms are known, many of which are edible that include prominent species like button mushrooms, oysters, porcini and chanterelle. 

However, many species of mushrooms are not edible and may provoke stomach problems and vomiting if consumed, and in some circumstances may be deadly, for example, the well-known death cap mushroom. This mushroom can be mistaken for the white button mushroom. The death cap mushroom is the most dangerous poisonous mushroom species currently known, causing 90−95% of all deaths from mushroom poisoning. Cholera-like symptoms of nausea, vomiting, and diarrhea begin 10−20 h after ingestion, followed by damage to liver and kidney, and eventually death. The major toxins that lead to death inare  this species are cyclopeptides and amino acids (2).

Mushrooms are being studied to an increasing extent. Many are used for their health benefits, with a variety of types exhibiting therapeutic properties.

How to safely use mushrooms?

Many raw mushrooms possess a naturally-occurring toxin, agaritine, which can be inactivated by heat. 

Proper heat treatment destroys toxins and enables the natural digestive enzymes to make most of the intrinsic benefits of mushrooms.

Edible mushrooms should be tenderized by heating to a minimum of 140℉, for several hours, more desirably beyond 200℉ to discharge their nutrients and make them digestible and safe to consume.

In addition, mushrooms can carry toxic metals. Similar to plants and microbes, fungi are intimately involved in soil mineral weathering and element cycling. Extracellular enzymes transform soil organic matter, which is often insoluble or adsorbed on mineral surfaces, into soluble products. This complex chemical action leads to a very interesting and not yet well understood phenomenon: uptake, transport, and accumulation of various chemical elements in mushroom fruit bodies, including metals such as mercury and silver, which can be toxic (1).

Are mushrooms healthier when cooked?

Yes, mushrooms are healthier when cooked. They possess anti-cancer properties. When mushrooms are cooked, the nutrients become more digestible for the body. However, as a large amount of water is lost while cooking, they also lose some of those nutrients so you will have to eat more.

For instance, the protein content of raw mushrooms is around 3.3 g.  When cooked, they lose a significant amount of their nutritional weight, leaving only 1.5 g of protein.

The same number of raw mushrooms contains 24 calories, which declines to 20 calories when cooked. The fiber content, on the contrary, actually improves from 1.1 g in raw mushrooms to 1.6 g after cooking.

The sugar content in raw mushrooms declines from 2.1 g to 1.7 g when cooked. The fat content stays the same i.e., 0.35 g before and after cooking.

However, studies show that cooking mushrooms reduced flavonoid concentrations and flavonoid concentration for raw mushrooms was higher. Flavonoids loss was proportional to cooking time and microwave cooking retained the most flavonoids compared to boiling or steaming. On the other hand, cooking increased chitin content regardless of preparation technology (3).

Health benefits of mushrooms

For biotechnologists and chemists, mushrooms have been proven to be great sources with diverse and unique bioactive secondary metabolites which exhibit a range of beneficial properties as therapeutic agents for various diseases. For the public, edible species constitute an ideal source of carbohydrates, dietary fiber, and proteins, with delicious taste and low calories (2).

Dose of selenium: Mushrooms provide enough selenium required by the body, thus helping to prevent cancer. Almost 9 µg of selenium are present in a cup of mushrooms. Bioactive compounds of mushrooms, particularly ergothioneine, ergosterol, vitamin D, beta-glucan and selenium have been favorably linked to immune function (3).

Source of potassium: Mushrooms are a rich source of potassium that helps to regulate heart, muscle and nerve functions.

Source of vitamin D: Surprisingly, mushrooms are a great source of vitamin D. vitamin D helps to promote the absorption of calcium in the digestive tract, hence promoting bone health. Studies show positive effects of mushroom extracts consumption to bone density (3).

Beneficial for the brain: Mushrooms possess an antioxidant, Ergothioneine, which plays a major role in boosting brain functions.

Lowers cholesterol: Mushrooms also assist in lowering cholesterol levels in the body. A study showed that the consumption of white button mushroom cooked in olive oil (2 g/kg body weight/day) was associated with significantly lower glucose, total cholesterol, low-density lipoprotein, triglycerides and body weight, and higher high-density lipoprotein, compared to the control (3).

Good for weight loss: Since mushrooms have low calories, rich fiber, protein and antioxidant content, so are useful for weight loss. In a study, mushroom consumption was associated with lower hunger, greater fullness and decreased prospective food consumption compared with a protein-matched beef portion (3).

In addition, studies show that the consumption of more than 2 g per day of white button mushroom reduced the odds of ovarian cancer by 32%. In a sample of prostate cancer patients, mushroom extract at increased doses (4–14 g extract daily;equivalent to 40–140 g fresh mushroom) was associated with decreased total prostate specific antigen levels in 36% of patients (3).

Different mushrooms and their toxic compounds

At present, >100 mushroom toxins have been characterized, but many toxic compounds have not yet been identified in several mushroom species. In 2019, toxic mushrooms were classified on the basis of their key clinical features into six groups (2): 1. cytotoxic mushroom poisoning; 2. neurotoxic mushroom poisoning; 3. myotoxic (rhabdomyolysis) mushroom poisoning, 4. metabolic, endocrine, and related toxicity mushroom poisoning; 5. gastrointestinal irritant mushroom poisoning; 6. miscellaneous adverse reactions to mushrooms. Some examples are:

Psilocybin: Psilocybin is a toxins from the Genus Psilocybe. A certain variety of mushrooms (magic mushrooms) contain a compound known as psilocybin that can induce hallucinations, hearing and eyesight problems, muscle weakness, tiredness and nausea. This toxin exerts psychoactive effects by altering neurotransmission through serotonin receptors. In contrast, psilocybin has potential clinical applications in treating anxiety disorders, obsessive compulsive disorder, major depression, and cluster headaches (2).

Carcinogens: Some varieties of edible mushrooms, including the common white button mushrooms, possess some amounts of certain carcinogens when raw.

Formaldehyde: Some mushrooms, for example, Shiitake mushrooms have some amounts of naturally-occurring formaldehyde, which is poisonous to humans (4). 

Hydrazine: Portobello mushrooms have hydrazine, a critically toxic compound and a potential carcinogen. This will be further converted in the liver into nitrosamide, which is carcinogenic (2).

Research has found that these compounds have the ability to cause damage to DNA by inducing chromosomal breakage and mutations, which can, as a result, lead to cancer.

The bright side, though, is that these carcinogenic toxins can be destroyed by heat, which is why it is always recommended to cook these mushrooms prior to consumption.

Conclusion 

In this brief guide, we have provided an answer to the question, “Can you eat mushrooms raw?”. We have further elaborated on the health benefits and dangers of eating raw mushrooms. 

References