What are Medicinal Mushrooms?

Mushrooms have been valued as food and as medicine since ancient times. Archaeological evidence indicates that mushrooms have been an important food source for humans since our early hunter-gatherer days, with over 2000 species of mushroom known to be edible. Nutritionally, mushrooms are a good source of fibre, protein, vitamins and minerals, and are low in calories.¹ Many mushrooms have also been used medicinally, especially in Asian traditional medicine systems. Medicinal mushrooms contain many biologically active compounds, such as polysaccharides, most notably β-glucans, as well as terpenoids, polyphenols, peptides, vitamins and minerals. Various mushroom species have demonstrated immunomodulatory, anti-inflammatory, anti-cancer, antioxidant, hypoglycaemic and hypocholesterolaemic effects.¹

Active Constituents of Medicinal Mushrooms

Beta-Glucan Polysaccharides

The primary constituents of medicinal mushrooms are the polysaccharides, which are a structural component of the mushroom cell walls. The most important polysaccharides are the beta-glucans. When consumed, these bind to receptors on human immune cells, including dectin-1, toll-like receptors, and CR3 complement receptors, thereby modulating immune function and activating T cells, natural killer cells and macrophages. As well as immunomodulatory effects, beta-glucans have demonstrated anti-inflammatory, antioxidant, anti-cancer, antimicrobial and antidiabetic effects.² The beta-glucan content varies between different species of mushrooms, with the highest levels seen in Trametes versicolor (Turkey Tail) and Lentinula edodes (Shiitake)¹ – see Table 1.

Table 1: Beta-Glucan Content of Different Medicinal Mushrooms¹

Other Compounds

Terpenes, and terpenoids are also important constituents, which can enhance the immune system by promoting gene expression for immune-related proteins. They also possess anti-inflammatory, antioxidant, and antitumor properties. Ganoderma mushrooms such as Ganoderma lucidum (Reishi) are particularly rich in terpenoids. Mushrooms also contain proteins with cytotoxic and anticancer effects, known as fungal immunomodulatory proteins (FIPs), which have various mechanisms of action. Additionally, proteins-like lectins, which bind to sugars, play roles in immunity and cell interactions, and have immunomodulatory, antitumor, and antiproliferative properties.

Other bioactive fungal metabolites include phenolic compounds (antioxidants with various mechanisms), laccases (copper-containing oxidases), and fatty acids.

Mushrooms Quality

The phytochemical profile of medicinal mushrooms varies, depending on a range of factors including the plant part used, the growing conditions and what the mushrooms are grown on. A mushroom is made up of the fruiting body (the above ground part) and the hyphae and mycelium (the below ground filamentous network), which have differing phytochemical profiles. Traditionally, only the fruiting body was used medicinally.

Figure 1: Anatomy of the Mushroom³

The growth medium used to grow the mushrooms also has a large impact on the mushroom’s composition. For example, a study found that Reishi mushrooms grown on wood logs contain higher levels of the active terpenoids and phenolic compounds, and had higher antioxidant and hypoglycaemic effects, than Reishi grown on growth medium in sacks.⁴ Additionally, cultivating mushrooms under controlled, organic conditions can yield mushrooms with lower levels of heavy metals and contaminants compared to wild grown mushrooms grown in polluted environments.¹

Key Mushroom Species

Turkey Tail

Trametes versicolor (Turkey Tail), previously known as Coriolus versicolor, has traditionally been used as a “magic herb” in Asian regions and particularly in traditional Chinese medicine. It is used to promote good health, strength, and longevity. Known as yunzhi or tunzhi in China, its medicinal uses were recorded in ancient texts including the “Compendium of Materia Medica” and “Shen Non-Compendium Medica”. Currently, highly concentrated extracts of the active beta-glucan constituents glycoprotein PSK and polysaccharide peptide PSP are routinely used in Japan and China in integrated cancer therapy, in conjunction with chemotherapy or radiotherapy.² [Venturella]

Reishi

Ganoderma lucidum is known as Reishi in Japan, lingzhi (meaning ‘spirit plant’) in China or simply the ‘mushroom of immortality’. Its species name ‘lucidum’, meaning ‘shiny’ or ‘brilliant’, refers to the appearance of its fruiting bodies, which can be described as lacquered-looking reddish-orange to black caps. Nearly all Reishi growing wild in Japan are found on old Japanese plum trees. Despite their rarity, Reishi is one of the most widely used medicinal mushrooms in the world.^2,5,6 It has been long used to promote longevity and well-being, and is included in the ancient text “Shen Nong’s Materia Medica” (206 BC-8 AD).² It is now widely used as an adjuvant treatment in cancer patients, and is valued for its  anticancer, immunomodulating, antioxidant, hepatoprotective, antihyperlipidaemic, antidiabetic, and tonic properties.²

Shiitake

Lentinula edodes (Shiitake) has been renowned in Japan and China as a food and medicine for thousands of years for its strengthening and restorative properties.⁶ It was recorded in the 14th century by a Chinese physician that Shiitake was beneficial for the treatment of malignancy.⁷ It’s active beta-glucan constituent Lentinan is widely used in Japan as an adjunct in cancer patients today. Shiitake may be beneficial in any condition associated with lowered immune function, thanks to its immunomodulatory effects.²

Maitake

Grifola frondosa is also known as Maitake. In Japanese, Maitake means ‘dancing mushroom’. Some say it is so named because in ancient times people who found the mushroom danced with joy, since it could be exchanged for its weight in silver. Others say the name is derived from its appearance. Its fruiting bodies are small tongue- or fan-shaped caps fused to stalks that overlap with adjacent fungi forming masses that resemble butterflies in a wild dance, occurring at the base of stumps and on roots. Maitake is also called hen of the woods and sheep’s head.⁶ It was used historically in traditional Chinese medicine to calm the mind and the nerves, as well as to improve spleen and stomach conditions, and for haemorrhoids.⁸

Conclusion

Mushrooms have been utilised as both food and medicine for thousands and thousands of years. When grown and processed under ideal conditions, they can be a valuable medicine for the support of immune function and general well-being.

References

¹ Łysakowska P, Sobota A, Wirkijowska A. Medicinal Mushrooms: Their Bioactive Components, Nutritional Value and Application in Functional Food Production—A Review. Molecules. 2023 Jul 14;28(14):5393.

² Venturella G, Ferraro V, Cirlincione F, Gargano ML. Medicinal Mushrooms: Bioactive Compounds, Use, and Clinical Trials. IJMS. 2021 Jan 10;22(2):634. DOI:10.3390/ijms22020634

³ Wille ECG, Bento CRC. Filamentous Fungi Growth as Metaphor for Mobile Communication Networks Routing. Adv Electr Comp Eng. 2021;21(2):59-66. DOI:10.4316/AECE.2021.02007

⁴ Song T, Zhang Z, Liu S, Chen J, Cai W. Effect of Cultured Substrates on the Chemical Composition and Biological Activities of Lingzhi or Reishi Medicinal Mushroom, Ganoderma lucidum (Agaricomycetes). Int J Med Mushrooms. 2020;22(12):1183-90. DOI:10.1615/IntJMedMushrooms.2020037133

⁵ American Herbal Pharmacopoeia. Reishi mushroom - Ganoderma lucidum: standards of analysis, quality control, and therapeutics. Santa Cruz: American Herbal Pharmacopoeia; 2006.

⁶ Hobbs C. Medicinal mushrooms: an exploration of tradition, healing, & culture. Summertown; Botanica Press; 1995.

⁷ Jones K. Shiitake: the healing mushroom. Rochester: Healing Arts Press; 1995.

⁸ Mizuno T, Zhuang C. Maitake, Grifola frondosa: pharmacological effects. Food Rev Int. 1995;11(1):135-149. DOI: 10.1080/87559129509541024