Maitake mushroom is an edible mushroom consumed widely in Asia as food and used in traditional medicine to treat diabetes and hypertension. Maitake extracts are commercially available as dietary supplements marketed to “enhance immune function” and to treat HIV and cancer. Beta 1,6-glucan, a protein bound polysaccharide, has been identified as the active constituent.
Maitake extracts exhibited hypoglycemic effects in a few studies (9) (12). Preliminary data suggest that maitake may be useful in inducing ovulation in patients with polycystic ovary syndrome (PCOS) (22).
Maitake demonstrated antitumor effects (16), enhanced bone marrow colony formation, reduced doxorubicin toxicity (11), and inhibited tumor metastasis in vitro (13). In a study done in mice, oral maitake extract promoted maturation of hematopoietic cells to functionally active myeloid cells and enhanced peripheral blood leukocyte recovery following chemotoxic bone marrow injury (17). A novel polysaccharide, MZF, was shown to induce dendritic cell maturation and enhanced antitumor response (20). Maitake also enhanced interferon activity against bladder cancer cells (18) and alleviated inflammation associated with inflammatory bowel disease (19).
In a small non-controlled study, tumor regression or significant improvements in symptoms were observed in half of the subjects using Maitake extract (5). In another study of postmenopausal breast cancer patients, oral administration of maitake extract was shown to have immunomodulatory effects (14). Oral maitake also enhances neutrophil and monocyte function in patients with myelodysplastic syndrome (25). More studies are underway to establish maitake's anticancer potential.