Maitake (Grifola frondosa) is an edible mushroom whose polysaccharide (beta-glucan) extracts are sold to support the immune system, especially by people with cancer. Early trials show it changes immune markers in the blood, both up and down.
Also known as: Grifola frondosa, maitake D-fraction, hen of the woods.
A breast cancer trial tested 0.1 to 5 mg per kg of liquid extract twice a day for 3 weeks (Deng 2009); a myelodysplastic syndrome trial used 3 mg per kg twice a day for 12 weeks (Wesa 2015). These are study protocols, not a recommendation.
It is sold in the US as a dietary supplement. Under the 1994 dietary supplement law (DSHEA), FDA does not approve dietary supplements before they are marketed, and the maker, not FDA, is responsible for safety and labeling. The National Cancer Institute lists maitake among the commonly used medicinal mushrooms and says FDA has not approved medicinal mushrooms to treat cancer or any other condition (NCI PDQ).
What studies show: in a dose-escalation trial in 34 women after breast cancer treatment, maitake extract both raised and lowered different immune markers, with intermediate doses sometimes suppressing them, and the authors warn it may depress as well as enhance immune function (Deng 2009). In 18 people with lower-risk myelodysplastic syndrome, 12 weeks raised lab measures of white cell function; the trial measured immune markers rather than how patients fared (Wesa 2015).
Safety: no dose-limiting toxicity was found in the breast cancer trial; two women stopped early for mild nausea, joint swelling, rash or itching (Deng 2009). In the MDS trial it was well tolerated, and 4 people developed eosinophilia without symptoms (Wesa 2015).
We could not find a single published half-life or time to peak for maitake that applies to a supplement dose, so we do not list one. Plant extracts are mixtures of many compounds, so no single figure would describe them.
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