Maitake Extracts and Their Therapeutic Potential — A Review

Alternative Medicine Review, Feb, 2001 by Mark Mayell

Maitake researchers have identified several ways maitake can counter cancer:[17-25]

* By protecting healthy cells from becoming cancerous

* By helping to prevent cancer metastasis

* By slowing or stopping the growth of tumors

Studies have confirmed all three of these potential benefits. Preliminary but unpublished clinical data from a noncontrolled study also suggest a fourth potential benefit: maitake may work in conjunction with chemo-therapy to lessen its side effects, such as hair loss, pain, and nausea, and to boost its positive effects.

In a study of maitake's cancer-preventive potential, 20 five-week-old mice were injected once with a carcinogenic substance (3-MCA, methylcholanthrene). Beginning on the fifteenth day after injection, 10 mice were fed 0.2 mg of maitake D-fraction for 15 consecutive days. The other 10 (the control group) received saline solution. After 30 days the number of mice with cancer was 30.7 percent in the maitake group and 93.2 percent in the control group. Nanba notes that Lentinan has also been shown to be effective against MCA, but needs to be administered through i.v. injection for 10 consecutive days to achieve a similar inhibition ratio, "suggesting that maitake D-fraction has the stronger ability to enhance the immune system."[26]

In another study, researchers exposed mice to a known urinary bladder carcinogen (N-butyl-N'-butanolnitrosoamine; BBN) every day for eight weeks and then fed them medicinal mushrooms, including maitake, shiitake, and oyster mushrooms. All 10 mice treated only with BBN developed bladder carcinoma. Mushroom feeding significantly reduced the number of bladder cancers, with maitake being the most effective. Carcinomas were observed in 46.7 percent of the maitake-treated mice compared to 52.9 percent and 65 percent for shiitake and oyster, respectively. The mushrooms also prevented a significant depression in lymphocyte and NK cell activity.[27]

In a study on the potential antimetastatic activity of maitake, researchers

injected liver carcinoma cells into the rear footpad of mice. Mice were divided into three groups. The control group received normal feed, while two other groups received either whole maitake powder as 20 percent of their diet or 1 mg/kg of D-fraction intraperitoneally 10 times. After 30 days the mice were observed for tumor foci metastasized to the liver. In the control group 100 percent of the animals showed metastasis. By comparison, the D-fraction prevented 91.3 percent of that total, and the maitake-feed diet 81.3 percent (p [is less than] 0.01) (Figure 1).[28]

[Figure 1 ILLUSTRATION OMITTED]

Researchers administered 1 mg/kg/day of a purified maitake polysaccharide fraction (MT-2; 3-branched beta-1,6 glucan) intraperitoneally 24 hours after implantation of MM-46 tumor cells, IMC-carcinoma cells, or Meth-A fibrosarcoma cells in the axillary region of experimental male mice. On the twenty-fifth day after the cells were implanted, the solid tumors were extirpated and weighed to obtain a tumor growth inhibition ratio. The maitake fraction was found to cause significant tumor growth inhibition, ranging from 25.6 percent for Meth-A fibrosarcoma to 49 percent for MM-46.[29]