A new study found that white button mushroom (Agaricus bisporus) consumption reduced myeloid-derived suppressor cells (MDSCs) in both prostate cancer mouse models and patients. Usually, MDSCs help us, but in cancer, they switch sides and prevent the immune system from attacking the tumors. In mice, the treatment shrank tumors by 47.39% without side effects. In prostate cancer patients, 3 months of white button mushroom tablets similarly reduced circulating MDSCs and activated immune cells, suggesting it could slow prostate cancer progression.