Shiitake Mushroom Overview June 10 2014
Shiitake has been cultivated in China since the Song Dynasty in 1100 AD. A woodcutter named Wu San Kwung cut into a log with shiitake and later noticed the mushrooms growing where his ax had struck. This was the beginning of log cultivation. Today, numerous farmers are engaged in shiitake production in China.
They can be grown, with lower yields, on birch logs stacked above ground. Logs must be freshly cut and stacked, with mycelium plugs or sawdust spawn sealed with cheese wax. Newer sawdust plug spawn has a Styrofoam backing and is self-sealing. Both work fine. The logs need moisture and should be watered once a week if nature does not provide timely rains. A number of companies in Scotland utilize birch for shiitake cultivation. Oak is their wood of choice.
Shiitake has been used in traditional Chinese and Japanese Kampo medicine for centuries to increase stamina and circulation and help to alleviate arthritis, diabetes, high blood cholesterol, and immune deficiency.The dried powder and purified polysaccharides help stimulate the immune system.
Medicinal Use and Chemical Constituents
Shiitake's medicinal benefits are based in their chemical compounds, as discussed below:
■ Twelve different polysaccharides, lentinan, LEM (heteroglucan protein) from mycelia, lignins, KS-2 (alpha mannan peptide) glycoproteins, eritadenine, methyl sulphide, ergosterol, ergocalciferol, 33 percent protein, 47 percent complex carbohydrates, sugars including xylose and arabinose, B12, and thirty-seven enzymes. The molecular structure of lentinan sugars forms a helix that resembles the helix of DNA.
■ Mycelium: peptide mannans, double stranded RNA, eritadenine, c-AMP modulating endocrines, phyto-hemaglutinine, guanile monophosphate, and ergosterol.
LEM, or Lentinula edodes mycelium, is a protein-bound polysaccharide that has been shown to inhibit HIV infection of cultured human T-cells and potentiate the effect of AZT against viral replication. In a phase II study, 107 HIV-positive patients were treated with didano-sin for six weeks. After this time, eighty-eight patients were given two milligrams of lentinan per week intravenously, while the control group was given only the drug. The combined treatment significandy increased CD4+ cells after thirty-eight weeks compared to the control.
Lentinan has been found effective in increasing T-cell production when given at low doses, but at increased amounts, patients show lower T-cell counts.
A lignin-rich fraction from LEM called JLS-18 has been found to possess seventy times the antiviral activity of LEM itself.
EP3 is lignin that shows high activity against HIV in the lab. It reduced replication by 90 percent and completely inhibited the toxic effect of HIV to T-cells. Herpes simplex I and II and western equine encephalitis virus were also completely inhibited. Partial inhibition of mumps, measles, and polio viruses was observed
In one randomized, controlled trial, 275 patients with advanced or recurrent stomach cancer were given chemotherapy with or without lentinan. The best results were found when the mushroom extract was administered before chemotherapy and in those without prior chemotherapy.
A monosaccharide derived from the mycelium of several Basidiomycete mushrooms, including shiitake, cultivated in a fermentation tank is known as Active Hexose Correlated Compound, or AHCC. After a series of steps and freeze-drying, a product with an exceptionally low molecular weight of five thousand daltons is produced. The active nutrient is acetylated beta-glucan, which enhances the immune system. More than seven hundred hospitals in Japan use it as part of protocols associated with chemotherapy to reduce hospital infections and support against the formation of abnormal cells. More than eighty research studies have been conducted. It appears to stimulate macrophages as well as increasing their numbers. This leads to increased production of cytokines like IL-12 and TNF, LAK and CTL cells directly, and interferon indirectly.
Animal research suggests it may be more effective at enhancing IL-12 levels in Th-1 dominant individuals.
A prospective cohort study with AHCC from February 1992 to January 2002, was conducted on 269 patients with hepatocellular carcinoma with some on placebo and others on the drug. Survival rate was 79 percent for the AHCC group and 51 percent for the control group.
Another study involved 229 patients with gastrointestinal cancer. All patients received chemotherapy and 127 were additionally given AHCC. After twenty-seven months, survival rate for the AHCC group was 66.7 percent and only 35 percent for the control group. After ten months, AHCC survival rate was 89.9 percent and for the control group was 55.9 percent.