Maitake Mushroom (Grifola frondosa) Enhances Cognitive Function in Healthy Older Japanese: A Randomized, Double-Blind, Placebo-Controlled Trial.

Extended longevity has resulted in an increased number of patients with dementia. Therefore, new methods for treating and preventing dementia are highly desirable. Multiple health benefits have been reported for Grifola frondosa (maitake mushrooms). In this study, we investigated the safety and effects of continuous intake of maitake mushrooms on cognitive function in healthy older individuals. We conducted a randomized, double-blind, placebo-controlled trial over 18 wk targeting 47 healthy Japanese individuals aged 60 y or older. The individuals were randomly divided into three groups: a Y10M group consumed bread containing 50 g of the maitake mushroom strain Y10M, a C5304 group consumed bread containing 50 g of the maitake mushroom strain C5304, and a placebo group consumed bread without maitake mushrooms. No participants discontinued the intervention due to adverse effects in any group. The Y10M group showed a significant improvement in cognitive assessment based on the Japanese version of the Montreal Cognitive Assessment (MoCA-J) score compared to the placebo group after the intervention. However, no difference was observed in the MoCA-J scores between the C5304 and placebo groups. The activity of natural killer cells, a type of immune cell, was also significantly augmented in the Y10M group and positively correlated with MoCA-J scores. These results suggest that improved cognitive function is, at least in part, attributable to the activation of the immune system. This study suggests that consumption of maitake mushrooms may help inhibit the decline in cognitive function in healthy older individuals.