Medicinal Properties of Shiitake June 16 2014
Protein 13-18%; niacin (mg/100 g): 55; thiamin (mg/100 g): 7.8; riboflavin (mg/100 g): 5.0. Ash: 3.5-6.5%. Fiber: 6-15%. Fat: 2-5%. Vetter (1995) found that the caps had 15.24% protein while stems had 11%.
Lentinan, a water-soluble polysaccharide (B-1,3 glucan with B-1,6 and B-1,3 glucopyranoside branchings) extracted from the mushrooms, is approved as an anticancer drug in Japan. The Japanese researcher Chihara was one of the first to publish on the anticancer properties of Shiitake, stating that lentinan "was found to almost completely regress the solid type tumors of Sarcoma 180 and several kinds of tumors including methylchloranthrene-induced fibrosarcoma in synergic host-tumour system" (Chihara, 1978, p. 809). The mode of activity appears to be the activation of killer and helper "T" cells.
Another heavyweight polysaccharide, called KS-2, isolated by Fujii et al. (1978), also suppressed Sarcoma 180 and Ehrlich ascotes carcinoma in mice. Other protein-bound fractions have shown differing degrees of antitumor activity. Clearly, a number of anti-tumor compounds are produced in Shiitake besides the well-known lentinan.
In the past twenty years, more than a hundred research papers have been published on the chemical constituents of Shiitake and their health stimulating properties. In an early study (Sarkar, 1993), an extract from the cultured mycelium of Shiitake interrupted the replication of the type 1, herpes simplex virus. Ghoneum (1998) has shown that an arabinoxylane derivative from fermenting Shiitake is effective in slowing the HIV virus. In clinical trials H the San Francisco General Hospital, Gordon (1998) found that a combination of lentinan with didanosine (ddI) showed a mean increase of 142 CD-4 cells/mm3 over a 12-month period compared to a decrease in CD4 cells in patients treated with ddl alone. Odani et al. (1999) has isolated a novel serine proteinase inhibitor from the fruitbodies with a molecular mass of 15,999. In a study on the effect of a novel low molecular polysaccharide fraction on human cells, interleukin 1 and apoptosis on human neutrophils decreased while increasing interleukin 1 and apoptosis in the monocytic (U937) human leukemia cells. (Sia et al., 1999). Yamamoto et al. (1997) found that Shiitake's mycelium produces a water soluble lignin-polysaccharide fraction, unique from lentinan, which has potent anti-viral and immunopotentiating activities in vitro and in vivo. These studies confirm the medical significance of this species, and encourage further research.
In a series of clinical studies by Ghoneum et al (1994, 1995, 1996), patients afflicted with a variety of cancers, some with advanced malignancies, were treated with mycelially derived hemicellulose compounds and showed significant improvement. Ghoneum (1998) found that arahinoxylane, a fraction from the fermentation of Shiitake, Turkey Tail (Trametes versicolor), and the split gill mushroom (Schizophyllum commune), increased human NK activity by a factor of 5 in 2 months. Ghoneum's studies are the first clinical trials with cancer and mushrooms in the United States.
Shiitake has also shown promise in lowering blood pressure. (Kabir and Yamaguchi, 1987; Jong et al., 1991.) Novel antibiotics have recently been isolated from Shiitake. (Hirasawa, 1999). The cholesterol-lowing compound was identified as eritadenine, an adenine derivative.
A very small percentage of individuals are allergic to Shiitake mushrooms, and a rare form of dermatitis, exacerbated by sunlight, has been reported in Japan (Hanada et al. 1998).
For more information on the medicinal properties of Shiitake, consult Mori et al. (1987), Fujii et al. (1978), Jong (1991), Ladanyi et al. (1993) and Jones (1995).