Extracts and polysaccharides from different mushrooms, including Ophiocordyceps sinensis, Trametes versicolor, Lentinula edodes and Grifola frondosa have been shown to exert an inhibitory effect on influenza virus in vitro and in vivo through their modulation of immune response1-4. Mycelial extracts of edible mushrooms have also been shown to be effective as adjuvants for intranasal influenza vaccine producing a high influenza virus specific IgA and IgG response in nasal washings and serum respectively5.

Medicinal mushrooms can be used prophylacticlly at the start of the ‘flu season’ to maintain immune competency, or taken at the onset of symptoms to lessen the duration and severity of colds.

1. In vivo anti-influenza virus activity of an immunomodulatory acidic polysaccharide isolated from Cordyceps militaris grown on germinated soybeans. Ohta Y, Lee JB, Hayashi K, Fujita A, Park DK, Hayashi T. J Agric Food Chem. 2007;55(25):10194–10199.
2. Inhibitory effect of TNF-α produced by macrophages stimulated with Grifola frondosa extract (ME) on the growth of influenza A/Aichi/2/68 virus in MDCK cells. Obi N, Hayashi K, Miyahara T, Shimada Y, Terasawa K, Watanabe M, Takeyama M, Obi R, Ochiai H. Am J Chin Med. 2008;36(6):1171–1183.
3. Antiviral and interferon-inducing activities of a new peptidomannan, KS-2, extracted from culture mycelia of Lentinus edodes. Suzuki F, Suzuki C, Shimomura E, Maeda H, Fujii T, Ishida N. J Antibiot. 1979;32(12):1336–1345.
4. Depression of early protection against influenza virus infection by cyclophosphamide and its restoration by protein-bound polysaccharide. Tsuru S. Kitasato Arch Exp Med. 1992;65(2-3):97–110.
5. Induction of cross-protective immunity against influenza A virus H5N1 by an intranasal vaccine with extracts of mushroom mycelia. Ichinohe T, Ainai A, Nakamura T, Akiyama Y, Maeyama J, Odagiri T, Tashiro M, Takahashi H, Sawa H, Tamura S, Chiba J, Kurata T, Sata T, Hasegawa H. J Med Virol. 2010;82(1):128–137.