Shiitake

Lentinula edodes (Lentinus edodes)
(from Medicinal Mushrooms – A Clinical Guide by Martin Powell)

Japanese name – Shiitake
Chinese name – Xiang Gu (Fragrant Mushroom)

L. edodes is an important ingredient in Asian cuisine and its annual production (2 million tons) is second only to the common button mushroom (Agaricus bisporus). As well as being delicious, it has an excellent nutritional profile with high levels of B vitamins and pro-vitamin D2 (ergosterol)1.

Since the 1960’s L. edodes has been the subject of intensive research as an anti-cancer agent. LEM, a crude mycellial extract from L. edodes with proven immuno-modulating properties contains glycoproteins, nucleic acid derivatives, vitamin B compounds and ergosterol while Lentinan, a highly purified polysaccharide from L. edodes, is licensed in Japan for the treatment of gastric cancer.

Other bioactive compounds from L. edodes include eritadenine, which shows promise for lowering cholesterol levels, and Lentin, an anti-fungal protein which also inhibits HIV-1 reverse transcriptase activity and proliferation of leukemia cells2.

Uniquely among the medicinal mushrooms high levels of consumption have been reported to cause an allergic skin reaction termed Shiitake Dermatitis and although there are no reports of reactions at supplementation levels caution or an alternative choice of mushroom are advised in those with sensitive skin3,4.

Cancer – Analysis of 5 clinical trials with a total of 650 participants shows that the addition of Lentinan at 2mg/week to standard chemotherapy offers a significant advantage over chemotherapy alone in terms of survival for patients with advanced gastric cancer, with patients with lymph node metastasis having slightly better results than patients without5. Additional trials confirm increased survival, reduced side effects from chemotherapy and improved quality of life in patients with colorectal, hepatocelluar, breast cancer and metastatic prostate cancer6. In a trial with 69 metastatic prostate cancer patients the 50% survival length of treated and control patients was 48 and 35 months respectively, while the five-year survival rate of treated patients was 43% against 29% in the control group7.

Although usually delivered by injection, Lentinan is also orally bioavailable although the clinical dosage is likely to be significantly higher 8,9.

Cholesterol Control – Eritadenine has been shown to be a potent inhibitor of S-adenosylhomocysteine hydrolase and to accelerate excretion of ingested cholesterol and its metabolic decomposition. When added to the diet of rats (0.005%), eritadenine caused a 25% decrease in total cholesterol in one week1.

Early studies indicated that levels found in whole shiitake mushrooms may be too small to have a significant effect but recent research has shown the presence of eritadenine at levels 10 times higher than originally, indicating therapeutic possibilities for shiitake, particularly in cases where patients have shown statin intolerance10,11.

In clinical trials dried L. edodes (9g/day) decreased serum cholesterol 7-10% in patients suffering from hypercholesterolemia and 90g/day fresh L. edodes (equivalent to 9g/day dried mushroom) led to a decrease in total cholesterol of 9-12% and triglycerides of 6-7%1.

Hepatitis B – Polysaccharides extracts from L. edodes have been shown to be hepatoprotective and in a study of 40 patients with chronic viral hepatitis B, LEM at 6g/day for 4 months improved liver function and resulted in 17 patients becoming seronegative for Hbe antigen1,9.

HIV – LEM increased the T-cell count in HIV patients with AIDS symptoms from 1250/mm3 to 2550/mm3 after 60 days1.

Candida – In vitro studies show L. edodes to have consistently high levels of anti-microbial activity, including the highest anti-candidal action among several mushroom species (for further discussion see section on Candidiasis).

CLINICAL SUMMARY

Main Therapeutic Application – Cancer, cholesterol control, especially as an adjunct to statins
Key Components – Polysaccharides and eritadenine Dose – 2-6g/day polysaccharide extract for immune support. 9g/day dried fruit body for cholesterol control.

Because eritadenine’s cholesterol lowering action differs from that of prescription statins or natural sources of statins such as P. ostreatus or M. purpureus, it can usefully be combined with them in cholesterol control protocols.

Caution
– Patients with sensitive skin or on anti-coagulant medication.

1. Shiitake (Lentinus edodes) Wasser SP. Encyclopedia of Dietary Supplements. 2005
2.Lentin, a novel and potent antifungal protein from shitake mushroom with inhibitory effects on activity of human immunodeficiency virus-1 reverse transcriptase and proliferation of leukemia cells. Ngai P.H, Ng T.B. Life Sci. 2003;73(26):3363-74.
3. Shiitake dermatitis now occurs in France. Hérault M, Waton J, Bursztejn A.C, Schmutz J.L, Barbaud A. Ann Dermatol Venereol. 2010;137(4):290-3.
4. Shiitake dermatitis: flagellate dermatitis after eating mushrooms. Hautarzt. Haas N, Vogt R, Sterry W. 2001;52(2):132-5
5. Individual patient based meta-analysis of lentinan for unresectable/recurrent gastric cancer. Oba K, Kobayashi M, Matsui T, Kodera Y, Sakamoto J. Anticancer Res. 2009;29(7):2739-45.
6. Effects of lentinan in advanced or recurrent cases of gastric, colorectal, and breast cancer. Taguchi T. Gan To Kagaku Ryoho. 1983;10(2 Pt 2):387-93.
7. Effect of lentinan for advanced prostate carcinoma. Tari K, Satake I, Nakagomi K, Ozawa K, Oowada F, Higashi Y, Negishi T, Yamada T, Saito H, Yoshida K. Hinyokika Kiyo. 1994;40(2):119-23.
8. Inhibition of human colon carcinoma development by lentinan from shiitake mushrooms (Lentinus edodes). Ng M.L, Yap A.T. J Altern Complement Med. 2002;8(5):581-9.
9. The medicinal benefits of Lentinan (β-1, 3-D glucan) from Lentinus edodes (Berk.) singer (Shiitake Mushroom) through oral administration. Yap A.T, Ng M.H. Int J Med Mushr. 2005;7(12):170
10. Production of the bioactive compound eritadenine by submerged cultivation of shiitake (Lentinus edodes) mycelia. Enman J, Hodge D, Berglund K.A, Rova U. J Agric Food Chem. 2008;56(8):2609-12.
11. Quantification of the bioactive compound eritadenine in selected strains of shiitake mushroom (Lentinus edodes). Enman J, Rova U, Berglund K.A. J Agric Food Chem. 2007;55(4):1177-80.
12. Shiitake, Lentinus edodes: Functional properties for medicinal and food purposes Mizuno T. Food Reviews International, 1995;1(1):109-128

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