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International Journal of Medicinal Mushrooms

Impact factor: 1.357

ISSN Print: 1521-9437
ISSN Online: 1940-4344

International Journal of Medicinal Mushrooms

DOI: 10.1615/IntJMedMushr.v3.i4.20
8 pages

Beneficial Effects of Edible and Medicinal Mushrooms on Health Care

Tetsuro Ikekawa
Japanese Association of Integrative Medicine (JAIM). Association for Popularization of Integrative Medicine and Treatments (NPO, Japan), Sanshin Building, 3F, 2-15-14 Uchikanda, Chiyoda-ku, Tokyo 101-0047,Japan

ABSTRACT

Studies on antitumor activities of Basidiomycetes have been in progress at the National Cancer Center Research Institute of Japan since 1966. At present, studies on mushrooms are being conducted worldwide. At the time when we started the studies, it had been said in Japan that hard mushrooms such as Polyporaceae (saruno koshikake in Japanese) were effective against cancer. We therefore tested such hard mushrooms using a bioassay to measure the so-called "host-mediated" antitumor activities, but the results were not always satisfactory including Trametes versicolor (L.: Fr.) Lloyd (kawaratake) or Phellinus linteus (Berk. et Curt.) Teng (meshimakobu). However, the aqueous extracts of edible mushrooms showed high growth inhibitory activity against solid Sarcoma 180. Antitumor polysaccharides such as glucans were isolated from the mushrooms, and among them, a β-(1−3)-glucan, which we isolated from Lentinus edodes (Berk.) Sing, (shiitake), was named lentinan and used clinically by a narrow adaptation in Japan. Another popular edible mushroom, Flammulina velutipes (Curt.: Fr.) P. Karst. (enokitake), also has high antitumor activity, and polysaccharides and a low molecular weight protein-bound poly-saccharide (EA6) were isolated. It was demonstrated that EA6 was active against tumors when administered orally (p.o.), but not so effective by intraperitoneal (i.p.) injection. It proved to be especially useful by p.o. in combination with surgery and other antitumor agents. By an antitumor screening test we isolated "proflamin" from mycelia of F. velutipes, which was highly active against allogeneic and syngeneic tumors when administered p.o in mice. An epidemiological study in Nagano Prefecture, Japan indicated that the cancer death rate among fanners producing F. velutipes as a main occupation was remarkably lower than that of other people in the Prefecture. A detailed epidemiological study is ongoing. The cancer prevention effect of Hypsizygus marmoreus (Peck) Bigel. (bunashimeji), one of the most popular edible mushrooms, was investigated. It also has high antitumor activity and a preventive effect in tumor metastasis. Cancer preventive study of edible mushrooms was performed. Control mice were bred on ordinary food and the treated mice with a food containing 5% of dried fruiting body of H. marmoreus. All mice were injected i.d. with a strong carcinogen, methylcholanthrene, and carcinogenesis in the mice was investigated. As a result of the 76-week observation, 21 of 36 of the control mice developed tumors, but only 3 of 36 mice in the treated group had tumors. The mechanism of cancer inhibitory and preventive activities of edible mushrooms was due to immunopotentiation and antioxidant activity. Thus, the intake of mushrooms proved to be effective in cancer prevention and growth inhibition. From ancient times, it has been said in Oriental traditional medicine that medicine and food have the same origin (Ishoku Dougen or Yakushoku Dougen in Japanese).