Health Benefits Of Shiitake Mushrooms

What are shiitake mushrooms?

The shiitake mushroom is one of the great representatives of the enormous potential of fungi. Scientifically known as Lentinus edodes or Lentinula edodes, shiitake is an edible, highly nutritious fungus native to East Asia. 

It has been used for thousands of years to improve general health, for its outstanding nutritional value, and also for its amazing health benefits, including immune system support and cholesterol reduction. A culinary-medicinal mushroom, shiitake is a nutritious and functional health food alternative: it is low in fat and high in fibre and protein, it is also a source of important vitamins and minerals, with oxidant compounds and β-glucans.^{1, 2, 3, 4}

Mushrooms are one of the most important functional foods for human beings - they are neither a plant nor an animal. They are part of a kingdom called Myceteae, which has attracted the interest of consumers who are now keenly interested in food bioactives that have beneficial effects on humans.⁵

First cultivated in China and later in Japan, where shiitake is considered the "elixir of life", it reached Thailand, Korea and Malaysia. Today, mainly due to its pharmacological properties and health benefits, shiitake is the second most popular cultivated edible mushroom on the world market and the first medicinal macrofungus to enter the field of modern biotechnology.¹

Health benefits of shiitake mushrooms

Several studies on biologically active compounds in edible mushrooms confirm the health benefits of shiitake: immunostimulant, antioxidant, antifungal, antimutagenic, antitumour, antibacterial, antiviral, anthelmintic, hepatoprotective, hypotensive, hypoglycaemic. It is a functional mushroom, whose polysaccharides have several remarkable biological activities, including immunomodulatory effects, anti-inflammatory and anti-ageing.^1,2,4,5

Shiitake has also been extensively studied for its oral health benefits. Due to its antimicrobial activity, shiitake mushroom consumption could be promoted as a preventive measure, with a focus on reducing the prevalence of dental caries and gingivitis.⁶ For these reasons, it is considered the king of mushrooms.

The health benefits of shiitake mushroom also include its medical support for conditions associated with weakened immune function (including AIDS), cancer, environmental allergies, fungal infections, common colds and flu, bronchitis, heart disease, hyperlipidaemia (including high blood cholesterol), hypertension, infectious diseases, diabetes, hepatitis, regulation of urinary incontinence.¹

Lentinan, isolated from shiitake mushrooms, is known to be a biologically active macromolecule with extremely potent activation of the human immune system, with anti-cancer activity. There is evidence that shiitake mushrooms act as immunomodulators (biological response modifiers, immunopotentiators, and immunostimulants). They are able to stimulate the nonspecific immune system and exert antitumor activity by stimulating the host defence mechanism, activating effector cells, such as macrophages, T lymphocytes, and NK cells, to secrete cytokines that are antiproliferative and induce apoptosis and differentiation of cancer cells. Its immunostimulatory effect boosts immune function as an important adjuvant therapeutic drug in cancer therapies and the management of carcinomas. Studies have shown that lentinan has a robust effect on improving quality of life and enhancing the efficacy of chemotherapy and radiotherapy in the treatment of various types of cancer, such as prostate cancer, ovarian cancer, lung cancer, stomach cancer, pancreatic cancer, colorectal cancer, duodenal cancer, cervical cancer, non Hodgkin's lymphoma.^5,7

Shiitake mushroom benefits also include heart health prevention and treatment of cardiovascular disease, acting in the reduction of blood cholesterol, mainly through the action of antioxidants and eritadenine, a substance capable of reducing blood levels of LDL, mainly from the ingestion of shiitake mushroom extract or from ingestion of dried shiitake mushroom.^4,5,8

Imbalances in the gut microbiota and impaired immunity are one of the major causes of ageing. They are associated with declining health. Studies suggest the importance of the polysaccharides present in medicinal mushrooms, such as shiitake, as prebiotics which, by modulating the gut microbiota, have great potential in the prevention and treatment of immunosenescence.⁹

Nutritional facts 

Lentinula edodes contains a considerable amount of protein with high nutritional value, comparatively similar to the nutritional value present in meat (beef) and higher than that of soya and beans. Functional foods rich in protein, such as shiitake, are important for tissue formation, body mass gain, and milk production, and are therefore necessary for healthy growth in children and adolescents, as well as during pregnancy and lactation.¹⁰

Shiitake also contains a significant concentration of some important vitamins (b vitamin, c vitamin, and d vitamin). Vitamin B6, vitamin B9, vitamin B12, vitamin C, vitamin D2, and vitamin D3 in shiitake mushrooms have been also studied for treating hypercholesterolemia, inflammation, hypertension, and osteoporosis.¹¹

Lentinula edodes has a low content of lipids. It has 9 essential amino acids, minerals (such as Calcium, Iron, Potassium, and Zinc), and a high content of fibre, which help the body to function properly and strengthen the immune system. 

In addition, shiitake mushroom has a wide range of functional metabolites, including polysaccharides, lectins and bioactive secondary metabolites such as lentinan, a β-glucan with immunomodulatory activity the most important polysaccharide known, because it potentiates the immune system, increasing the body's natural defences. The derived polysaccharides have been studied as the most valuable compounds a source of numerous bioactive substances with multiple beneficial health effects: anti-cancer, antioxidant, antimicrobial, and immunomodulatory properties.^2,3

Our immune system can be supported by natural products with antioxidant activity. In this respect, dietary antioxidants are of great importance. They are potential protective agents that reduce oxidative damage. Wild mushrooms, mane mushrooms, maitake mushrooms and our shiitake mushrooms in particular have been extensively studied for their antioxidant properties.¹²

Uses of shiitake mushrooms

First cultivated in East Asia, the health benefits of mushrooms date back thousands of years, when they were already being used either as food for health maintenance or as medicines for the treatment of disease. 

In traditional Chinese medicine (TCM), phytotherapy has been used as one of the most important tools for the prevention and treatment of a large number of syndromes. Nowadays, ancient TCM remedies are being re-investigated using modern scientific methods to ensure their efficacy and safety and they are developed as first-class dietary supplements as well as new medicines. Agaricus blazei Murill (a mushroom originating in Brazil); Cordyceps mushroom (a parasitic fungus) and Lentinus edodes - our shiitake mushroom, are some of those herbal products elected to be studied.¹³

Several shiitake-derived products are marketed and sold as dietary supplements because of the health benefits of shiitake mushrooms. As a source of biologically active compounds with medicinal value, it is used in complementary medicine and is also considered a nutraceutical. Shiitake has been studied for its enormous potential for therapeutic applications. It has been suggested that shiitake may boost the immune system (as an important anticancer and antiviral agent), protect the liver and reduce cholesterol.^1,2,5

Shiitake mushroom has an intense flavour. It is an important cuisine in East Asia. Nowadays, it is often used in both Oriental and Western cuisine, in rice, sauces, flours, gratins, soups, and casseroles. We can find fresh shiitake mushrooms or dried shiitake, as well as shiitake mushroom extract powder.

Taking advantage of the additive and synergistic effects of the bioactive compounds they contain, mushrooms can be used directly in the diet to promote health. In fact, oriental medicine often prescribes a natural hypocholesterolemic and anti-sclerotic diet, preventing and treating heart health. In this sense, shiitake mushrooms are a great food alternative food and a potential natural cholesterol medicine. Indeed, it has recently been discovered to have a significant cholesterol-lowering effect. The therapeutic implications of mushrooms are vast and intensive research is required, especially to detail the mechanisms of various health benefits of mushrooms.

Side effects and other concerns

The only known adverse reaction to the consumption of shiitake mushrooms is the eruption of pruritic, erythematous papules, known as shiitake dermatitis, a lentinan toxic reaction that may occur after eating insufficiently cooked shiitake mushrooms.⁶

Summary

The increase in mushroom consumption worldwide is probably a response to this shift towards a new paradigm in which the field of lifestyle medicine is growing: people are taking a protagonist role in their health care, making better choices to adopt healthy habits with a focus on disease treatment and prevention. 

Shiitake is the most studied species as a supporting natural therapy for treating and preventing various cancers. Mushrooms have an anti-cancer activity that is associated with polysaccharides present in the cell wall of the fruiting body (fruit), which can stimulate the production of antibodies that inhibit tumour growth. 

The shiitake mushroom has tremendous therapeutic potential. It is a healthy food, rich in proteins, fibres and lipids, vitamins, and important minerals, in addition to many other nutritional and culinary values, it is a functional food with numerous medicinal and curative properties, a source of biologically active compounds relevant to complementary medicine, such as  immunopotentiating, dietary supplements, anticancer, antiviral, hepatoprotective, hypocholesterolemic, anti-ageing.

The main attribute of mushrooms is their nutraceutical properties, which have been the main focus of researchers around the world. More pharmacological and physiological research on the properties of mushrooms needs to be done, especially with a focus on detailing and clarifying the mechanisms of the various health benefits: boosting the immune system, reducing cholesterol, maintaining homeostasis, regulating biorhythms, curing, preventing various life-threatening diseases such as cancer, stroke and heart disease.⁵