Lentinus edodes (shiitake)

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Shiitake mushroom, native to East Asia, is cultivated worldwide for its purported health benefits. The fresh and dried forms of the mushroom are commonly used in East Asian cooking. 

Lentinan (1,3 beta-D-glucan), a polysaccharide isolated from shiitake is thought to be responsible for the mushroom’s beneficial effects. Lentinan is used widely in Japan and China as an adjuvant to cancer chemotherapy. Although it has been shown to have anticancer effects lentinan is considered a biological response modifier, rather than having a direct cytotoxic effect on tumor cells. Studies conducted with shiitake extracts in vitro and in animal models reveal immunostimulatory, antiviral, hepatoprotective, antihypercholemic, antiproliferative, cytotoxic, antimutagenic, and anticaries properties. Latcripin-13 domain isolated from shiitake was shown to exhibit antitumor activity in lung cancer cells.

In a randomized dietary intervention in young adults, eating shiitake mushrooms for 4 weeks altered immune function. An orally administered shiitake mycelial extract decreased the incidence of chemotherapy-associated adverse effects in a small study of patients with advanced gastrointestinal cancer, and in combination with immunotherapy, improved quality of life in cancer patients. 

Mechanisms of Action

Trametes versicolor is thought to be a biological response modifier. PSK has been found to induce cytokine expression in human peripheral blood mononuclear cells in vitro. In other studies, PSP, as well as a Coriolus extract, selectively induced apoptosis of human promyelocytic leukemia HL-60 cells. PSP also increased apoptotic cell death in cells that had been treated with camptothecin. In these cells, PSP reduced cellular proliferation, inhibited cell progression through both the S and G2 phases of DNA replication, reduced 3H - thymidine uptake, and prolonged DNA synthesis time. An additional in vitro study showed that a medicinal mushroom blend that included Trametes inhibited cell proliferation and induced cell cycle arrest at the G2/M phase in the invasive human breast cancer cell line MDA-MB-231. DNA-microarray analysis indicated that the mushroom extract inhibited the expression of cell cycle regulatory genes and suppressed metastatic behavior through the inhibition of cell adhesion, cell migration, and cell invasion . The inhibition of metastatic behavior was linked to the suppression of urokinase plasminogen activator (uPA). PSP has also been shown to inhibit the interaction between HIV-1 gp120 and CD4 receptor, HIV-1 transcriptase activity, and glycohydrolase enzyme activity associated with viral glycosylation.

Several animal studies report of synergism between PSK and biologic therapies, including a concanavalin A-bound L1210 vaccine and the IgG2a monoclonal antibody against human colon cancer cells. PSP induces cytokine production and T-cell proliferation, and prevents immune suppression due to cyclophosphamide in animal models. Peritoneal macrophages isolated from mice that were fed PSP show increased production of reactive nitrogen intermediates, superoxide anions, and tumor necrosis factor.

Non-small cell lung cancer patients have increased leukocyte and neutrophil counts, and increased serum IgG and IgM after consumption of PSP. Healthy volunteers as well as breast cancer patients who used a formula containing Trametes and Salvia were found to have elevated counts of T-helper lymphocytes (CD4+), a high ratio of CD4+/CD8+, and elevated absolute counts of B-lymphocytes. TNF-alpha and IL-8 gene expression were also found to be significantly induced after PSK administration in healthy volunteers and gastric cancer patients, although individual response varied. PSK was shown to induce apoptosis in promyelomonocytic leukemia HL-60 cells, and p38 MAPK (mitogen-activated protein kinas) was found to play an important role in this process.

Dosage

The dose of Shiitake used in clinical trails for during cancer treatment was 8 gm. For general immuno-support and cancer prevention a formula containing several mushroom species (which may contain 20-250 mg of Shiitake may be reasonable. 

Safety

Shiitake appears to be well tolerated and the weight of the available evidence supports its safety with rare reported side affects. There are rare reports of allergic skin reactions (dermatitis).

Where to get it

Fabio Almeida