Shiitake (Lentinula edodes, Xiang Gu /fragrant mushroom/ edible mushroom) belongs to the stalked wood-destroying fungi (basidiomycetes). Its body is composed of a foot and a cap. The cap has a fleshy, solid structure, is convex (umbrella-shaped), initially under-rolled, and straightens as the mushroom ages. It is usually 5 cm in diameter, light to dark brown with scales and sometimes white spots. The leg (spine) is light, also scaly. It is short and located in the centre of the hat.

The name Shiitake mushroom is a compound of two words 'shii', meaning oak tree (Quercus cuspidata) and 'take', which is the Japanese word for mushroom. This is based on the fact that Shiitake is a wood-boring fungus and gets its nutrients from the trees on which it grows. These are mainly dead oak trees. It grows mainly in temperate climates in Asia - China, Japan and Korea.

Shiitake is in great demand, but there is very little to be found in the wild, so it is cultivated artificially. Around 2 million tonnes are grown annually worldwide. The largest producers are Asian countries, but also the USA, Australia and others.

The most commonly used wood for cultivation is 'logs' or sawdust. Again, these are the various types of oak trees on which it grows in the wild. Shiitake can also be grown at home. It is not very demanding. Thetype of substrate we use can also influence the composition of the mushroom.

Uses of Shiitake:

Shiitake plays an important role in Asian cuisine. The mushroom has a distinctive, almost 'smoky' aroma and a meaty texture. It can be dried or used fresh. It is used in meat dishes, soups, sauces and can be prepared as a side dish.

In addition to its use as a food, Shiitake is part of traditional Chinese medicine, which uses it as a 'medicine'. In Asia, knowledge of Shiitake dates back to before our era. Written references to Shiitake date back to 199 AD. It is a Japanese writing that describes how the Kyusuyas, a tribe in Japan, brought the mushroom to the Japanese emperor as a precious gift to honour him. Chinese writings are also rich in references to Shiitake. In them, it is referred to as the elixir of life. In China, Shiitake also began to be cultivated and grown artificially very early on. The first references date back to the Sung Dynasty (960-1127). Another text, which dates back to 1313, accurately describes the procedures for cultivating and growing Shiitake. This writing comes from the pen of Wang Cheng. Although the mushroom has been known for thousands of years, it was not included in the natural history system until 1877. It was named and classified by M. J. Barkeley. At that time it was given the name Agaricus edodes, which was changed in 1976 by D. Pegler, as he reclassified it from the mushroom family to the Lentinula group.

Ingredients of Shiitake

The mushrooms are very similar in composition, but each has its own specific characteristics. Different ratios of bioactive components and some compound quite typical and unique to it.

Shiitake is 88-92% water. The caloric value of 100 grams of dried mushroom, i.e. water-free, is 387-392 kcal.

Polysaccharides and other sugar compounds

Mushrooms are very rich in polysaccharides, complex sugars. These are twofold in nature, firstly they are insoluble in water. These are coarse fibres, which include e.g. chitin and lignin. Then there are the soluble polysaccharides, which are absorbed from the digestive tract into the blood. Insoluble fibre, which is not absorbed, serves as a source of energy for the gut symbiotic bacteria. Soluble has the ability to influence processes throughout the body.

The most important polysaccharides are undoubtedly beta glucans. Both (1-4)- and (1-6)-type beta-D-glucans can be found in Shiitake. This is a different type of branching of the main chain and side chains. This gives the glucans different functionality. The best known polysaccharide, named after the fungus, is lentinan. It is found in the cell walls of mature mushrooms. Lentinans are β-D-glucans with bonds at the (1→3)- and (1→6)- positions. It is a homopolymer, i.e. it is made up of only one type of simple sugar that binds together to form long chains, in this case glucose. Lentinates are water soluble and therefore absorbable from the intestine and can be used to influence body functions. They have the advantage of being able to withstand high temperatures (they are not destroyed by cooking a mushroom, for example) and also alkaline environments. Many studies have been conducted with lentinans to test their effects. Read more in our articles.

Another compound typical of Shiitake is KS-2, which combines a carbohydrate and a protein. Unlike lentinan, it can be obtained from mycelia. It is composed of mannan and amino acids, e.g. alanine, proline, serine, threonine. This compound was isolated in 1978, since then several researches have been conducted to look into its effects.

However,Shiitake does not only contain polysaccharides, there are also simple sugars. These include mannose, trehalose, glycerol, arabinol, etc.

Since Shiitake is very popular, there are standardised products available on the market. These are known as LEM and LAP (EP3). LEM is an extract from fungal mycelia. Both extracts are rich in glycoproteins (proteins with sugar components attached) and contain glucose, galactose, xylose, arabinose, mannose and fructose. They also contain nucleic acids and compounds derived from them, B vitamins and ergosterol.

Amino acids, proteins and enzymes

Mushrooms are also a source of amino acids, which are the basic building blocks of proteins. It also contains those amino acids that the body cannot synthesize on its own from the food it receives. In Shiitake we can find alanine, glutamic acid, lysine, arginine, aspartate, proline, glycine, methionine, phenylalanine, leucine, cysteine, valine, threonine, etc.

In Shiitake, there are not only building blocks, but also complex and functional proteins, which include enzymes. Shiitake is enzymatically very active. It has to break down the wood it grows on in order to extract the necessary nutrients from it. It contains, for example, cellulases, lactases, amylases, xylanases, manganese (II) dependent peroxidases and many others. Thus, in addition to breaking down wood, Shiitake can also break down many environmental pollutants, including toxic and carcinogenic substances such as pesticides and dioxins.

Fats in Shiitake

Mushrooms, including Shiitake, also contain fats. These are mainly fatty acids. Saturated ones are represented, but also unsaturated ones, which are very beneficial for the organism. Their ratio is a very favourable 22% vs. 78%. It is worth mentioning the most saturated ones. These are palmitic acid, stearic acid and myristic acid, which are saturated. With one unsaturated bond, oleic acid and fatty acids with multiple unsaturated bonds, i.e. linoleic and linolenic acid.

Minerals, trace elements and vitamins in Shiitake

Shiitake also carries a large amount of mineral, trace elements and vitamins.

Among the most important ones are potassium, magnesium, phosphorus, calcium, iron, zinc, manganese, copper, chromium... Among the vitamins, we mention mainly ergosterol, the precursor of vitamin D2. This is formed from ergosterol when exposed to UV light. Other vitamins are from the B group, including vitamin B12.

Purine alkaloids

Alkaloids are plant substances that have many biological effects. One of the best known is erythadenine, also known as lentinacin and lentysin, in chemical nomenclature it is a 2(R),3(R)-dihydroxy-4-(9-adenyl)-butyric acid. It reduces the activity of the enzyme S-adenosyl-L-homocysteine hydrolase, which is behind the formation of homocysteine, which is associated with many pathological processes in the body. Its formation is reduced. It also regulates the activity of the angiotensin converting enzyme, which is involved in the regulation of blood pressure, with a decrease in activity, less active angiotensin II is formed, which increases blood pressure.

Lycopene

Surprisingly, Shiitake may also contain lycopene. We used to associate this substance mainly with tomatoes. It is a substance from the carotenoid group with a terpenoid structure. Lycopene is best utilized in the body when the food containing it is cooked and fat is added. Lycopene is, among other things, a powerful antioxidant.

Lenthionine

Lenthionine is a sulphur-containing organic cyclic compound. It was extracted in 1967, when Japanese scientists described it in their paper. Like other sulphur compounds, lenthionine has a specific smell and gives Shiitake its aroma. It is produced in the mushroom during its lifetime by the conversion of lentinic acid.

Shiitake, of course, contains many more components. These are alcohol compounds, ketones, volatiles, which impart aroma and flavor.

Shiitake as a protector of nature

You can read about the effects of Shiitake in publicly available sources on the internet. For example, see www.cinskyherbar.cz. Here we mention another useful property of Shiitake, which is the degradation of harmful substances that accumulate in the environment, water, soil, etc. There have been many studies that have tested the effectiveness of Shiitake in removing various substances, it has been confirmed that it is capable of breaking down many compounds into inactive and harmless ones. These includepesticides, herbicides -terbuthylazine, diflufenican, etc. In addition, it can also degrade antibiotics from the waste water of pharmacological factories and hospitals that would otherwise enter watercourses. The effect of Shiitake on cephalosporins has been tested. It can also deal with substances released from plastics, phthalates, which act as endocrine disruptors, i.e. disrupt hormonal regulation in the body.

Shiitake is therefore a very versatile fungus that can affect us indirectly by improving the environment we live in.