An extract of the edible mushroom Maitaki, Grifola frondosa, rich in glucan polysaccharides, with potential immunostimulating activity. Upon oral ingestion, Maitaki mushroom extract may promote dendritic cell (DC) maturation, increase interferon gamma (IFN-gamma) and tumor necrosis factor alpha (TNF-alpha) production, and may enhance natural killer (NK) cell activity, thereby amplifying both innate and T cell-mediated immune responses against cancer cells. In addition, this extract may stimulate the production of granulocyte colony stimulating factor (GCSF) and promote hematopoiesis, and may improve the neutrophil count.