The First Randomised Trial on Maitake and Memory Is Here. Here's What It Found.

If you follow functional mushroom research, you've probably noticed that most of the conversation around cognition centres on one species: Lion's Mane. There are good reasons for that. The Mori et al. (2009) trial on Lion's Mane and mild cognitive impairment is one of the most-cited studies in the field.

But a new paper published in the Journal of Nutritional Science and Vitaminology suggests the relationship between mushrooms and cognitive function may run deeper than a single species.

Jogi et al. (2026) just published the first randomized, double-blind, placebo-controlled trial testing maitake mushroom (Grifola frondosa) specifically for cognitive function in healthy older adults. No animal models. No observational data. A proper RCT.

Here's what they found.

The setup

47 healthy Japanese adults aged 60 and over were randomly assigned to one of three groups. Two groups consumed bread containing 50 grams of maitake mushroom daily for 18 weeks, each group receiving a different maitake strain (Y10M and C5304). The third group received plain bread as a placebo.

Cognitive function was measured at baseline and after 18 weeks using three validated screening tools: the MMSE, HDS-R, and MoCA-J (the Japanese version of the Montreal Cognitive Assessment).

To confirm participants were actually absorbing the maitake, the researchers measured blood ergosterol levels. Ergosterol is a lipid found almost exclusively in fungi, making it an effective biomarker for mushroom consumption.

The results

The Y10M maitake group showed a statistically significant improvement in MoCA-J total score compared to placebo (p=0.045). When the researchers looked at the MoCA-J subscales, the improvement was driven specifically by the memory domain (p=0.024).

Neither the MMSE nor HDS-R detected significant differences between groups, but the researchers note this is consistent with how these tools perform. The MoCA-J is considered more sensitive for detecting subtle cognitive changes, particularly in healthy populations where decline is mild.

The C5304 strain group did not show significant cognitive improvement, which points to something the researchers discuss at length: strain matters. Two mushrooms of the same species, grown differently, can produce different outcomes.

The mechanism: NK cells and the brain

This is where the study gets particularly interesting.

The researchers measured natural killer (NK) cell activation before and after the 18-week intervention. NK cells are part of the innate immune system, and recent research has increasingly linked systemic immune activation to brain function.

The Y10M group showed significantly increased CD69 expression on NK cells compared to placebo. More importantly, the change in NK cell activation positively correlated with the change in MoCA-J scores (R=0.338, p=0.027).

The proposed pathway: maitake polysaccharides (beta-glucans) activate NK cells, potentially contributing to cognitive maintenance through immune-mediated mechanisms. Previous research has shown that NK cells can clear amyloid-beta in the brain and improve microglial function, offering a plausible biological link between immune activation and cognitive performance.

This matters because beta-glucans are not unique to maitake. They're the primary bioactive polysaccharides in Lion's Mane, Reishi, Chaga, Cordyceps, and most other functional mushroom species. If the immune-cognition pathway holds up in larger studies, it could help explain why multiple mushroom species appear to support cognitive function through different, overlapping mechanisms.

Limitations worth noting

The study is rigorous in design but has clear limitations that the authors are transparent about.

The sample size is small (47 participants, roughly 14-17 per group). The population is exclusively healthy older Japanese adults, so results may not generalize to other demographics. Diet was unrestricted beyond the bread intervention, and genetic or lifestyle factors were not controlled for.

The study was funded by YUKIGUNI FACTORY Co., Ltd., a maitake mushroom manufacturer. The authors state that the sponsor did not influence data collection or analysis and that the conflict of interest is disclosed. Still, it's worth noting when evaluating any industry-funded research.

What does this mean for the broader picture?

This isn't a study you'd build a product claim on. It's a single trial with a small sample.

But it's a meaningful addition to a growing body of evidence that functional mushrooms interact with cognitive function through multiple biological pathways, not just the direct neurotrophic effects most often associated with Lion's Mane.

The fact that strain-specific differences produced different outcomes also reinforces something we think about constantly: sourcing, cultivation, and extraction methods aren't marketing details. They're variables that change what the mushroom actually does.

If you want to read the full paper: Jogi EM et al. "Maitake Mushroom (Grifola frondosa) Enhances Cognitive Function in Healthy Older Japanese: A Randomised, Double-Blind, Placebo-Controlled Trial." J Nutr Sci Vitaminol, 72, 163-175, 2026.

This article is for educational purposes only. It is not intended to diagnose, treat, cure, or prevent any disease. Mycogenius does not sell maitake mushroom products.