Almond mushroom (Agaricus blazei Murill), also called “Himematsutake,” has been traditionally used in Brazil and Japan for its purported health benefits, including immune support. In the context of chemotherapy, there is some scientific evidence suggesting that extracts of almond mushroom may help reduce chemotherapy side effects. Several small clinical studies and animal experiments indicate that Agaricus blazei polysaccharides may modulate the immune system, potentially reducing symptoms like fatigue, nausea, and vulnerability to infections during chemotherapy. For example, a randomized, double-blind, placebo-controlled study published in 2011 in Evidence-Based Complementary and Alternative Medicine reported that breast cancer patients undergoing chemotherapy who received Agaricus blazei extract experienced less severe chemotherapy-induced side effects (such as appetite loss and alopecia) compared to placebo, though the sample size was small.

However, the overall quality of the evidence is low: studies tend to be small, sometimes lack rigorous controls, and results are not always consistent. Most research has focused on immunomodulatory effects rather than direct reduction of specific chemotherapy side effects. Systematic reviews note that while the mushroom has promise, more large-scale, high-quality trials are needed. Thus, the scientific evidence supporting its use for reducing chemotherapy side effects is preliminary and best described as limited but existent, meriting a moderate-low rating.