Shiitake (Shitake) mushrooms are a legendary gourmet treat, used for centuries in Asia as both food and remedy. Shiitake recipes are innumerable and delicious.

Shiitake is also one of the most thoroughly researched and documented medicinal mushrooms. Not only do they have excellent nutritive value; they also are the source of at least two important components with proven pharmacological effects--LEM (Lentinula edodes mycelium extract) and Lentinin. These two components have demonstrated strong antitumor activity.

The initial antitumor research was performed in 1969 by Tetsuro Ikekawa at Purdue University in West Lafayette, Indiana, along with colleagues at the National Cancer Center Research Institute in Tokyo. The researchers found that water extracts of shiitake and several other mushrooms collected in the wild produced high rates of tumour inhibition in mice (72 to 92%). Ikekawa later identified a polysaccharide in shiitake called lentinan as having powerful antitumor activity.

Part of any positive medicinal effects of shiitake may result from it serving as a dietary supplement, particularly the provision of various amino acids such as isoleucine, leucine, lysine, methionine, phenylalanine, threonine, and valine, as well as vitamins B1, B2, B12 and also mineral salts.

Regular intake may prevent rickets, especially in infants, which could be due to a disorder of phosphorus and calcium metabolism caused by vitamin D deficiency. Lentinula edodes is very rich in the provitamin - not present in quantity in vegetables. Ergosterol is converted to vitamin D in presence of sunlight. Vitamin D increases resistance against illnesses and has preventive and curative effects on colds.

Lentinula edodes also contains adenine and choline, which may prevent the occurrence of cirrhosis of the liver as well as vascular sclerosis. Tyrosinase contained in Lentinula edodes tends to lower blood pressure. Two other constituents which have been isolated from Lentinula edodes tend to reduce serum cholesterol.

Like many medicinal mushrooms, Shiitake acts by enhancing various immune system functions rather than attacking the tumor cells directly. Shiitake is used medically for any and all diseases involving depressed immune function including cancer, AIDS, environmental allergies, yeast infections, and frequent flu and colds. In addition, contains compounds effective in lowering cholesterol and treating high blood pressure.

In rare cases, there is an allergic dermatological reaction to Shiitake.

http://www.herbmed.org/Herbs/Herb171.htm:

Pharmacodynamics:

The mycelium-free culture fluid of Lentinus edodes was bacteriostatic against Streptococcus pyogenes, Staphylococcus aureus and Bacillus megaterium. The substance responsible for the activity was heat-stable, could be extracted with chloroform and had a molecular weight under 10000. Hatvani 2001

Hemagglutinating activity of culture liquid was substantially higher than mycelium for four strains of Lentinus edodes. The carbohydrate-binding capacity of the agglutinins was established. The lectin activity seem to be involved in the formation of hyphal aggregates of brown mycelial film. Tsivileva 2001

Shiitake extract showed an inhibitory effect on water-insoluble glucan formation from sucrose by crude glucosyltransferases of Streptococcus mutans JC-2 and S. sobrinus OMZ-176. The firmly adherent plaque in the artificial plaque formation test was strongly inhibited by shiitake extract. Shouji 2000

A critical review of existing data on the mechanism of whole mushrooms and isolated mushroom compounds, in particular (1-->3)-beta-D-glucans, and the means by which they modulate the immune system and potentially exert tumor-inhibitory effects. Borchers 1999

Antibacterials were extracted by chloroform, ethylacetate or water from Lentinus edodes, active against Streptococcus spp., Actinomyces spp., Lactobacillus spp., Prevotella spp., and Porphyromonas spp. of oral origin n contrast to general bacteria, which very little activy was found. Hirasawa 1999

Chemopreventive effects of plant polysaccharides (including Lentinus edodes) were compared using in vitro screening method of initiation and promotion processes in carcinogenesis and found to produced anti-genotoxic and anti-tumor promoting activities. Kim 1999

A novel Lentinus proteinase inhibitor has been purified from the fruiting bodies of Lentinus edodes. No apparently homologous proteinase inhibitors in the protein database were found, though there is a stong similarity to the propeptide segment of a microbial serine proteinase. Odani 1999

The aqueous extract of the shiitake mushroom was found to decrease IL-1 production and apoptosis in human neutrophils, as measured by ELISA and flow cytometry respectively. It was found to increase IL-1 production and apoptosis in the U937 monocytic cell line. Sia 1999

This review highlights some of the recently isolated and identified substances of higher Basidiomycetes mushrooms origin that express promising antitumor, immune modulating, cardiovascular and hypercholesterolemia, antiviral, antibacterial, and antiparasitic effects. Wasser 1999

An extract of culture medium of Lentinus edodes mycelia, JLS-S001, significantly blocked the release of infectious herpes simplex virus type 1 (HSV-1) from African green monkey kidney cells. Sarkar 1993

The active principle of EP3, a fraction from an extract of the culture medium of Lentinus edodes mycelia, which causes proliferation of bone marrow cells, and inhibits HIV replication in vitro, was characterized as a water-solubilized lignin. Suzuki 1990

Animal Studies:

Mice were pretreated with solutions of Shiitake, intraperitoneally injected15 d. later with N-ethyl-N-nitrosourea or cyclophosphamide and killed 24 or 48 h after treatment , results showing a high degree of variability, with some indications of an antigenotoxic effect.. de Lima 2001

In the control group of rats, total LDL-cholesterol concentration was significantly higher and fecal cholesterol excretion was significantly lower than the Lentinus Edodes group. Fukushima 2001

The mitosis index of hepatoma cells in vitro and the inhibition rates against implanted S-180 tumors in mice could be significantly decreased by treatment with the polysaccharide extracts from LentinusÊedodes. Jiang 1999

In this study, mice were treated with a carcinogen to induce urinary bladder carcinoma and it was observed that carcinoma occurred only in 9 of 17 mice (52.9%), in 7 of 15 mice (46.7%) and 13 of 20 mice (65.0%) treated with Lentinus edodes. Kurashige 1997

Lentinan (LNT), a beta-glucan derived from Lentinus edodes is known to work positively against cachexia in patients with malignant tumors. The results suggest that LNT partially normalizes TNF-induced cachexia in rats. Tamura 1997

Chronic oral administration Lentinus edodes treated with wet-heating and fructo-oligosaccharides significantly prevented pulmonary thrombosis induced by lactic acidosis in rats. However, decreases in the numbers of platelet and fibrinogen level by lactate were not changed. Otsuka 1996