Mushrooms are known for their nutritional and medicinal value as well as for the diversity of bioactive compounds they contain. Coriolus versicolor, aka “turkey-tail mushroom”, is a mushroom commonly found throughout North America, Asia, and Europe. The visible form of Coriolus versicolor is a fan-shaped mushroom with wavy margin and colored concentric zones. The colors of the distinctive layers created by these bodies may be light to dark brown or gray and resemble a turkey tail. Coriolus versicolor is an obligate aerobe that is commonly found year-round on dead logs, stumps, tree trunks, and branches. The fungus occurs throughout the wooded temperate zones of Asia, Europe, and North America and may be the most common shelf fungus in the Northern Hemisphere. The mushroom belongs to the family Basidiomycotina. This mushroom has long been treasured in China where it is called Yun Zhi, or “cloud fungus”, and in Japan where it is known as Kawaratake, or “mushroom by the river bank”.
Coriolus versicolor was recorded in the Compendium of Chinese Materia Medica by Li Shi Zhen during the Ming Dynasty in China, as being beneficial to health and able to bring longevity if consumed regularly. More than 120 strains of Coriolus versicolor were recorded in the Compendium of Chinese Materia Medica. According to the theory of traditional Chinese medicine (TCM), Coriolus versicolor has a slightly sweet taste and cold property, exerting its effects in the body via the liver and spleen. As a medicinal substance documented in some TCM classics, Coriolus versicolor is considered useful for dispelling heat, removing toxins, strengthening physique, increasing energy and spirit, and enhancing the host’s immune function. In the clinical practice of TCM, Coriolus versicolor is often indicated for various types of cancers, chronic hepatitis, and infections of the upper respiratory, urinary, and digestive tracts. In Asia, Coriolus versicolor is used as a preventive tonic and therapeutic agent for numerous conditions. And throughout the world, it has also become a popular mushroom for treating a variety of cancers. Overall, both the mycelium and fruiting body of the mushroom exhibit immune-enhancing properties and are shown to have potent anticarcinogenic activity.
Coriolus versicolor is primarily a biological response modifier. DNA-microarray analysis indicates that the mushroom extract inhibits the expression of cell cycle regulatory genes and suppressed metastatic behavior by inhibiting cell adhesion, cell migration, and cell invasion. The inhibition of metastatic behavior is linked to the suppression of urokinase plasminogen activator.1 A variety of other anticarcinogenic mechanisms have been observed in laboratory studies of Coriolus versicolor extract. Its extract can alter the expression of the p53 gene2 and suppress heat shock proteins3 that are overexpressed in a wide range of human cancers and are implicated in tumor cell proliferation.
The protein-bound polysaccharides or polysaccharopeptides produced by Coriolus versicolor are effective immunopotentiators, which are used to supplement chemotherapy and radiotherapy as well as the treatment of various infectious diseases. Actually, an extremely broad range of physiological effects has been associated with the use of Coriolus versicolor polysaccharopeptides. Some of the main effects include:
immunopotentiation by inducing production of interleukin-6, interferons, immunoglobulin-G, macrophages, and T-lymphocytes;
countering of immunosuppressive effects of chemotherapy, radiotherapy, and blood transfusions;
antagonization of immunosuppression induced by tumors;
inhibition of proliferation of various cancers by inducing production of superoxide dismutase (SOD), glutathione peroxidase, and general immune enhancement;
improvement of appetite and liver function; calming of the central nervous system;
enhancement of pain threshold;
and improvement of intestinal disorders.
Researchers discovered and labeled two of this mushroom’s active anticancer polysaccharides as PSK, or Polysaccharide-K, and PSP, or Polysaccharide-P. They are chemically similar, but PSK contains fucose, while PSP contains rhamnose and arabinose. Both PSK and PSP extracts exhibit immunomodulating and antitumor activity.4 PSK, also known and marketed as “Krestin”, has been studied most extensively and is in wide clinical use as an adjunctive and adjuvant cancer therapy in Japan and China. PSK has been shown to improve survival rates in patients with gastric5, 6 and colorectal7, 8, 9 cancers. Other research on PSK has been shown to have antioxidant capacity which may allow it to play a role as a normal tissue chemo- and radio-protector when used in combination with adjuvant or definitive chemotherapy and/or radiotherapy in the treatment of cancer, while it may also enable it to defend the host from oxidative stress.10, 11
In the in vitro situation, these polysaccharide extracts were found effective for activating T lymphocytes,12, 13, 14, 15, 16, 17, 18 B lymphocytes,19 monocytes/ macrophages,20, 21, 22 bone marrow cells,23 natural killer cells, and lymphocyte-activated killer cells as well as promoting the proliferation and/or production of antibodies and various cytokines such as interleukin (IL)-2 and IL-6, interferons, and tumor necrotic factor.24, 25 Based on the clinical data accrued to date, Coriolus versicolor extracts appear highly effective for restoring depressed blood levels of lymphocytes and IL-2 and weakened antitumor activity of natural killer cells.26, 27, 28, 29, 30, 31
Most Coriolus versicolor clinical research has focused on its effects on overall survival rates. In 1984, Sugimachi’s group at Kyushu University published a retrospective analysis of breast cancer patients with recurrent disease who were treated with Coriolus versicolor extract as Krestin (PSK).32 Some patients received chemotherapy only, while others received both chemotherapy with Krestin (PSK) immunotherapy. They demonstrated that the survival rate af