An Open Letter From Paul Stamets

In a time when the host defense of people is of primary concern, empowering the immune system has never been so important. Although many of those skilled in the art are aware of the immune-enhancing properties of mushrooms, few may realize that mushrooms are rich sources of natural antibiotics. While the cell wall glucans are well known for their anti-bacterial properties, few medical practitioners are aware that many of the secondary metabolites—the extracellular secretions by the mycelium—are exquisitely designed to combat a wide range of bacteria and other microorganisms (Anke 1989). Interestingly, some mushrooms are target-specific in their antibiotic properties, whereas others have more broad range effects. With an increasing number of gram-negative bacteria developing resistance to commercial antibiotics, mushrooms hold great promise for novel medicines in modern times. I personally believe that combinations of mushroom products, especially Polypores, help impart a protective immunological shield from a pantheon of infective diseases.

The pharmaceutical industry has been slow to explore mushrooms for antibiotic activity—until recently. We know now that more than 75% of Polypore mushroom species thus far surveyed show strong antimicrobial activity, and that 45% of 204 mushroom species analyzed—polypores and gilled mushrooms alike—showed activity (Suay et al., 2000). This higher concentration of effective antibiotics from Polypore mushrooms underscores that this barely explored group, in particular those with a long history of folkloric use by indigenous peoples, should be carefully surveyed (Atsumi, S., et al., 1990; Hirasawa et al., 1999).

Not only do the extracellular metabolites inhibit microbes, but so do the heavy molecular weight cell-wall polysaccharides. For instance, PSK from Trametes versicolor inhibits the growth of infectious yeasts such as Candida albicans (Tsukagoshi et al., 1984; Sakagami, 1991, 1993). Anti-tumor polysaccharides inhibit bacteria such as Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Hericium erinaceus shows strong anti-microbial activity against a broad range of infectious agents (Kawagishi, 1991 et al., 1994).

The good news is that these naturally occurring antibiotics are orally active and do not require a prescription for those seeking generalized protection. We encourage everyone to become more informed—and to inform others—especially health practitioners who are in doubt or are mycophobic. The following references will help in this education process.

Be well. Be safe. Be pro-active and strengthen your immune system—your host defense—with medicinal mushrooms.

Paul Stamets
Oct. 19th, 2001

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Selective Supporting Bibliography

Anke, T., 1989. "Basidiomycetes: a source of new bioactive secondary metabolites." Progress in Industrial Microbiology 27:51-66.

Atsumi, S., et al., 1990. "Production, isolation and structure determination of a novel beta-glucosidase inhibitor, cyclophellitol, from Phellinus sp." Journal of Antibiotics (Tokyo) Jan;43(1):49-53.

Hirasawa, M., N. Shouji, T. Neta, K. Fukushima & K. Takada, 1999. "Three kinds of antibacterial substances from Lentinus edodes (Berk.) Sing. (Shiitake, an edible mushroom)." International Journal of Antimicrobial Agents Feb; 11(2):151-157

Kawagishi et al., 1991. "Hericenones C, D and E, Stimulators of nerve growth factor (NGF)-synthesis from the mushroom Hericium erinaceum." Tetrahedron Letters vol. 32, no. 35, 4561-4564.

Kawagishi et al., 1994. "Erinacines A, B, C, strong stimulators of nerve growth factor synthesis, from the mycelia of Hericium erinaceum." Tetrahedron Letters 35 (10): 1569-1572.

Sakagami, H., T. Aoki, A. Simpson, & S.I. Tanuma, 1991. "Induction of immunopotentiation activity by a protein-bound polysaccharide, PSK." Anticancer Research 11:993-1000.

Sakagami, H., K. Sugaya, A. Utsumi, S. Fujinaga, T. Sato and M. Takeda, 1993. "Stimulation by PSK of interleukin-1 production by human peripheral blood mononuclear cells." Anticancer Research May-June 13(3): 671-5.

Suay, I, F. Arenal, F. Asenio, A. Basilio, M. Cabello, M.T. Diez, J. B. Garcia, A. Gonzalez del Val, J. Gorrochategui, P. Hernandez, F. Pelaez, M. F. Vicente, 2000. "Screening of basidiomycetes for antimicrobial activities." Antonie van Leeuwenhoek 78: 129-139.

Tsukagoshi, S., Y. Hashimoto, G. Fujii, H. Kobayashi, K. Nomoto, K. Orita, 1984. "Krestin (PSK)." Cancer Treatment Review 11:131-155.

Wasser, A.L. & Weis, A.L., 1999. "Medicinal properties of substances occurring in higher basidiomycetes mushrooms: current perspectives." (Review) International Journal of Medicinal Mushrooms vol. 1, 31-62.

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