Maitake Mushroom

• To prevent and treat cancer
  Laboratory studies and small uncontrolled studies in humans show that maitake extracts slow the growth of tumors and stimulate certain immune cells.
• To manage diabetes
  Maitake reduced blood glucose levels in a study of rats. Human data are lacking.
• To lower high cholesterol
  Evidence is lacking to support this claim.
• To lower high blood pressure
  Evidence is lacking to support this claim.
• As an immune stimulant
  Maitake stimulates the activity of certain immune cells in laboratory studies and in mice. It has also been shown to stimulate immune function in a small group of cancer patients. Larger studies are needed.
• To lose weight
  Evidence is lacking to support this claim.

Do Not Take If

• You are taking blood sugar-lowering medications: Maitake may increase their effects in Type-2 diabetic patients.
• You are taking warfarin: According to a case report, maitake can interact with warfarin resulting in an elevated international normalized ratio (INR).

Clinical Summary

Maitake is an edible mushroom consumed widely in Asia as food and used in traditional medicine to treat diabetes and hypertension. Its 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 also suggest that they may be useful in inducing ovulation in patients with polycystic ovary syndrome ⁽²²⁾.

In other studies, maitake demonstrated antitumor effects ⁽¹⁶⁾, enhanced bone marrow colony formation, reduced doxorubicin toxicity ⁽¹¹⁾, and inhibited tumor metastasis in vitro ⁽¹³⁾. In murine models, orally administered extracts promoted maturation of hematopoietic cells to functionally active myeloid cells and enhanced peripheral blood leukocyte recovery following chemotoxic bone marrow injury ⁽¹⁷⁾; and protected against cyclophosphamide-induced immunosuppression ⁽³³⁾. A novel polysaccharide, MZF, was shown to induce dendritic cell maturation and enhanced antitumor response ⁽²⁰⁾; a Selenium-enriched polysaccharide enhanced the antitumor activity of 5-Fu ⁽³⁰⁾; and a combination of polysaccharides and vitamin C was reported to induce apoptosis and autophagy in human hepatoma cells ⁽³¹⁾. Maitake also enhanced interferon activity against bladder cancer cells ⁽¹⁸⁾ and alleviated inflammation associated with inflammatory bowel disease ⁽¹⁹⁾.

Additionally, a maitake fraction showed antileishmanial effects ⁽³²⁾; and a maitake polysaccharide has been reported to ameliorate lipid metabolic disorders by modulating gut microbial phylotypes and by regulating genes involved in hepatic lipid and cholesterol metabolism ⁽³⁴⁾.

In a small non-controlled study, tumor regression or significant improvements in symptoms were observed in half of the subjects who took maitake extract ⁽⁵⁾. In a trial of postmenopausal breast cancer patients, oral administration of a maitake extract was shown to have immunomodulatory effects ⁽¹⁴⁾; and to enhance neutrophil and monocyte function in patients with myelodysplastic syndrome  ⁽²⁵⁾. More studies are underway to evaluate maitake’s anticancer potential.

Purported Uses

• Cancer prevention
• Diabetes
• High cholesterol
• Hypertension
• Immunostimulation
• Weight loss

Mechanism of Action

Maitake is thought to exert its effects through its ability to activate various effector cells, such as macrophages, natural killer cells, and T cells, as well as interleukin-1 and superoxide anions ^{(2) (3) (4) (13)}. Studies also suggest possible hypoglycemic activity ⁽⁹⁾. The antidiabetic effect of alpha-glucan may be due to its effects on insulin receptors by increasing insulin sensitivity and ameliorating insulin resistance of peripheral target tissues ⁽¹²⁾.

Maitake extract enhanced the growth and differentiation of mouse bone marrow cells treated with doxorubicin, a chemotherapeutic agent ⁽¹¹⁾. In addition, it may modulate antigen presentation as evidenced by protective effects against tumor implantation following transfer of dendritic cells from tumor-bearing mice that were treated with maitake ⁽¹⁵⁾.

In other studies, maitake D fraction demonstrated antitumor activity by upregulating expression of a proapoptotic gene, BAK-1 ⁽²³⁾; and prevented breast carcinogenesis, blocked tumor invasiveness, reduced angiogenesis, and increased overall survival in a murine model ⁽²⁶⁾. In addition, maitake polysaccharides were found to induce apoptosis GFPs induced via the mitochondrial-dependent apoptotic pathway in human breast cancer cells ⁽²⁷⁾; the beta glucan GFPBW1 also showed antitumor effects that are thought in part due to activation of macrophages via the Dectin-1/Syk/NF-κB signaling pathway ⁽²⁴⁾; and an orally administered maitake alpha-glucan was found to activate dendritic cells and macrophages in Peyer’s patches, resulting in induction of systemic antitumor T-cell response ⁽²⁸⁾.

Maitake also exerted antidepressant effects in mice, involving activation of the α-Amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptors, which are important mediators for the treatment of depression ⁽²⁹⁾.