Maitake showed promising anti-tumor and immunomodulatory properties in numerous preclinical trials.[1][1] However, it’s important to exercise caution when interpreting these results, because animal models of human disease often have significant specificity to that animal, due to biological and immunological differences from humans. Moreover, clinical (human) research on maitake’s effects on humans remains limited.
In one phase 1–2 clinical trial involving postmenopausal women with a history of (but no current) breast cancer, maitake extract was given orally at gradually increasing dosages over three weeks. The results showed that maitake increased the production of both stimulatory and suppressive cytokines, which play a key role in the regulation of the immune system response.[2] Although these findings did not lead to any observable clinical changes, they did suggest that maitake has complex effects on the immune system. Although some people may benefit from it, individuals with cancer should consider maitake supplementation carefully due to its immunosuppressive effects.
Another small non-randomized clinical trial assessed the levels of immunomodulatory markers in individuals with stage II–IV lung, lingual, gastric, and breast cancer who were given maitake’s D-fraction (a bioactive extract; see below under “How does maitake work?”) twice daily at different dosages based on the specific type of cancer. The study found slightly increased levels of T cells ( CD4+ and CD8+) and enhanced natural killer (NK) cell activity following treatment. Although these results suggest that matiake’s D-fraction may have immunostimulatory properties and a potential inhibitory effect on cancer progression, it’s important to note that the outcomes varied among different cancer groups. Additionally, two patients died despite the observed increase in T cells.[3] Given the study design and size, these findings should be interpreted with caution.
Finally, one non-controlled clinical trial reported mixed results for the effect of maitake on HIV infection. T cell (specifically CD4+ cells) activity and viral load improved for some participants, but worsened for others.[4] More clinical studies should be conducted to explore efficacy and safety of maitake supplementation for people with HIV.