Historical use of Shiitake mushrooms
Shiitake mushrooms (Lentinus edodes) are native to Asia where they have been cultivated for their culinary and medicinal value since the Ming Dynasty (1368 to 1644), who developed methods for cultivating these mushrooms on logs (Jones 1995). In the countries of East Asia Shiitake mushrooms are still used as ‘Functional foods’ for diseases involving depressed immune functions, including cancer, environmental allergies, frequent flu and colds, infectious disease, etc. (Bisen et al 2010).
Health benefits of Shiitake mushrooms
Scientists have isolated many health promoting compounds from shitake mushrooms, including polysaccharides, such as β-glucans, which have shown marked anticarcinogenic activity (Rop et al 2009), lentian known for its immunostimulatory effect (Zhang et al 2019), vitamin D2 (Cardwell et al 2018), immune boosting minerals such as zinc (Jones 1995), and all essential amino acids normally found in meat (Bano et al 1963), among others.
As reported by Ina et al (2013), lentinan has been shown in animal and laboratory studies to activate various immune cells, including the cytotoxic T cells, which can kill foreign cells, including cells infected with a virus.
A small 4-week study by Daie et al (2015) including 52 healthy males and females, who consumed either 5 or 10 g of dry shiitake mushrooms daily, demonstrated that regular consumption of Shiitake mushrooms resulted in improved immune cell proliferation and activation, a reduction in inflammatory proteins and increased secretory IgA (sIgA) production, the primary antibody produced by immune cells within the body (Stadtmueller et al 2016). As sIgA is found in mucous secretions, it is the first line of defence against bacteria, food residues, yeasts, parasites and viruses (Mantis & Forbes 2010).
A study by Hearst et al (2009) demonstrated that shiitake mushrooms extract has extensive antimicrobial activity against 85% of the organisms it was tested on. The extract has shown antimicrobial effects against 39 bacterial, yeast and fungal pathogens.
Although research is conflicting, consumption of Shiitake mushrooms (and other culinary mushrooms), in addition to a healthy diet and lifestyle practices, may offer a degree of protection against viral infections.
Arsenic in Shiitake mushrooms
A study by Llorente-Mirandes et al (2014) found that Shiitake products had high proportions of inorganic arsenic, a highly toxic compound and a carcinogen, used in the production of pesticides, herbicides, and insecticides. Although arsenic content appears to be highly variable, depending on soil arsenic concentration, excessive consumption of these mushroom may be counterproductive.
References available on request
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