A new study recently presented at the annual American Association for Cancer Research (AACR) Meeting in Washington, D.C. has reported that an extract of maitake mushroom reduced human breast cancer cell viability in the laboratory. Maitake mushrooms have various bioactive components. However, D-fraction, a protein-bound polysaccharide compound, appears to be the most potent for enhancing the immune system when administered in pill or injection form. Previous studies have reported that the combination of maitake fraction with chemotherapy might result in increased potential to reduce the size of lung, liver, and breast tumors. The authors cultured hormone receptor positive (ER+/PR+) MCF-7 cells, incubating them with increasing concentrations of liquid maitake D-fraction. The cells were evaluated for viability and for cell death (apoptosis). All of the experiments were performed in triplicate. Maitake-treated cells appeared to have higher apoptosis levels and poorer viability when compared to non-treated cells. The authors conclude that the results of the study could prompt the development of new therapeutic strategies against breast cancer based on maitake D-fraction.

Good mushroom choice for breast cancer

Maitake mushrooms are sold dried or fresh in upscale supermarkets and specialty markets. Maitake mushrooms have previously been shown to reduce growth, inhibit angiogenesis, and induce apoptosis of human breast cancer cells in the laboratory. However, a 2009 trial of maitake mushroom supplementation in postmenopausal breast cancer survivors found that, contrary to expectations, the maitake extract had both immune enhancing and immune suppressant effects at various doses. Therefore, we would caution breast cancer survivors and those at high risk from consuming maitake mushroom extracts.

A good choice for breast cancer prevention through diet might be white button mushrooms, the common supermarket mushrooms. White button mushrooms have among the most powerful proven breast cancer chemopreventive properties of the mushrooms that have been studied. They have been shown to suppress aromatase activity and estrogen biosynthesis, in addition to inhibiting proliferation of estrogen receptor positive breast cancer cells. Several studies have concluded that diets high in white button mushrooms may lower the risk of estrogen receptor positive breast cancer, especially in postmenopausal women, by reducing the production of estrogen from androgen in the body. Portobello and crimini mushrooms are closely related to white button mushrooms and may have similar properties.