Daily maitake mushroom consumption may boost memory in older adults

Daily consumption of a specific strain of maitake mushroom might help older adults preserve their memory and cognitive function. In a small study of healthy Japanese volunteers, participants who ate bread enriched with the mushroom showed improved cognitive test scores that correlated with enhanced immune system activity. The research was published in the *Journal of Nutritional Science and Vitaminology*.

As the global population ages, the number of individuals experiencing age-related cognitive decline continues to rise. When memory and judgment abilities degrade, it substantially impacts the daily routines and overall well-being of older adults. Because existing medical treatments for advanced dementia are highly limited, health professionals often focus on prevention.

Strategies frequently target mild cognitive impairment, widely known as MCI. This condition represents an intermediate phase between typical age-related memory issues and more serious forms of dementia. Health experts generally believe that stopping or delaying the progression of MCI offers a highly effective way to maintain long-term brain health.

Eri M. Jogi, a researcher leading the study out of the research and development department at Yukiguni Factory Co. Ltd. in Niigata, Japan, teamed up with clinical experts and academics from nearby institutions. They designed a trial to test whether eating maitake mushrooms daily could support the cognitive profiles of healthy older adults, driven by a growing urgency to address neurodegeneration.

“We felt a serious threat from the increasing number of dementia patients worldwide, and considered that maitake may help to reduce the risk of dementia,” Jogi said. “Since no curative treatment for dementia has been established, preventing the onset is considered important.”

While mushrooms have been a staple in Eastern medicine for centuries, human clinical data regarding their impact on the brain remains sparse.

“Maitake (Grifola frondosa) has various health benefits, and also has been suggested to improve cognitive function in animal models of dementia,” Jogi said. “However, the effects of maitake on cognitive function in healthy people have not been investigated. Therefore, we evaluated whether maitake contributes to maintaining healthy cognitive function in elderly people.”

Lifestyle habits, especially diet, represent an accessible approach to neurological maintenance. Past scientific inquiries have suggested that eating various types of mushrooms might lower the risk of developing cognitive disorders. For example, lion’s mane mushrooms have gained attention for their potential neuroprotective traits. Yet, the specific cognitive effects of other commonly consumed culinary mushrooms on human memory remain largely uncharted.

The maitake mushroom is a popular edible fungus in many Asian cuisines. Animal studies have indicated that maitake extracts might lower blood pressure, support metabolic health, and stimulate the immune system. Some laboratory experiments also hint that maitake components might protect nerve cells from oxidative damage.

The potential connection between maitake mushrooms, immune system activation, and brain protection represents an advancing area of neurobiology. Historically, researchers thought the brain existed completely separate from the body’s peripheral immune system. Today, biologists recognize that peripheral immune cells actively help maintain neurological function. They do this by assisting in the removal of cellular waste and managing localized inflammation.

Investigating this link, however, initially faced resistance from the scientific community.

“Maitake is widely known for its immunoregulatory function. Traditionally, enhancing the immune system was thought to be ineffective in improving cognitive function, so when we began this study, we received skeptical opinions from immunologists,” Jogi explained. “However, we found several recent reports that cognitive function can be improved via the immune system, and our study also observed similar results.”

Jogi and the team recruited a small study cohort of 47 healthy Japanese volunteers. The volunteers were between the ages of 60 and 85. The researchers utilized a randomized, double-blind, placebo-controlled design. In scientific research, this framework is considered the gold standard.

This experimental setup requires that participants are randomly assigned to their testing groups. It also mandates that neither the researchers nor the participants know who receives the active treatment. This framework helps eliminate physical bias and the placebo effect, where people feel better simply because they believe they are receiving a valid therapy.

The participants were divided into three groups. One group ate two daily pieces of bread containing 50 grams of a maitake mushroom strain called Y10M. A second group ate bread containing 50 grams of a different maitake strain known as C5304. The third group consumed a placebo bread containing no mushroom material at all.

The trial lasted for 18 weeks. The bread was baked with tomato and onion powders to hide the distinctive smell and taste of the fungi. This masking process ensured the participants could not guess which group they were placed in.

To verify the participants consumed the bread consistently, the researchers tracked a biological marker called ergosterol. Ergosterol is a type of fat molecule found almost exclusively in fungi. Blood tests administered throughout the trial confirmed that participants in both maitake groups had elevated ergosterol levels. This physical evidence proved they digested the active mushroom ingredients over the full testing period.

Measuring subtle shifts in memory among healthy adults is a challenging task over a short 18-week timeframe. The research team applied three distinct diagnostic tools. The Mini-Mental State Examination and the revised Hasegawa’s Dementia Scale are brief questionnaires widely used by doctors to diagnose established dementia. However, these basic tools often lack the sensitivity needed to detect minor cognitive struggles.

To account for this hurdle, the researchers also used the Japanese version of the Montreal Cognitive Assessment. This lengthy evaluation requires participants to complete tasks involving executive function, planning, language, and visuospatial processing. Medical professionals frequently use this assessment to identify the early warning signs of mild cognitive impairment before standard dementia tests pick up on any deficits.

The physical results across the three tests varied. Scores on the more traditional dementia tests did not change for any group. However, the group eating the Y10M maitake strain exhibited measurable improvements on their Montreal Cognitive Assessment scores. This improvement was largely driven by higher marks in the specific assessment category measuring memory recall.

These positive cognitive changes were isolated to just the one mushroom strain. The group eating the C5304 strain did not experience this memory boost. The placebo group also ended the trial with unchanged cognitive scores. General blood tests and physical exams confirmed that the mushroom bread was completely safe, causing no adverse side effects in any participants.

“We were most surprised to find that the effects on cognitive function and immunity differed depending on the maitake strains,” Jogi said. “It was also very interesting that cognitive function improved among healthy elderly people over a relatively short period of just 18 weeks.”

To understand why the Y10M strain benefited the brain, the scientists analyzed the participants’ blood for signs of immune activation. They specifically focused on natural killer cells, often abbreviated as NK cells. These specialized white blood cells operate as an early defense mechanism in the body, identifying and destroying infected or damaged tissue.

While typically associated with virus protection, NK cells also help regulate tissue repair. Emerging research indicates they assist related immune cells in sweeping away harmful protein debris from the nervous system. Blood analysis revealed that the Y10M group experienced an increase in the presence of early activation markers on their natural killer cells.

When the researchers compared the data sets, they observed a positive correlation between the activation of these immune cells and the improved memory scores on the cognitive assessments. The participants with the most active natural killer cells also tended to show the highest cognitive gains. These biological clues suggest a potential mechanism of action.

The researchers propose that consuming specific strains of maitake mushrooms stimulates peripheral immune cells, which naturally decline in efficiency as humans age. This immune revitalization might subsequently help the brain maintain its neural networks. By sweeping away metabolic waste, the activated immune system ultimately preserves memory function over time.

Like all dietary research, the published paper includes recognized limitations. The sample size of 47 individuals represents a small study, making it difficult to draw broad conclusions for the general public. The participants also maintained their normal, unrestricted diets at home, which introduces numerous variables that the researchers could not control.

Jogi also emphasized that the findings relate strictly to preservation rather than a cure. “An important point to note is that, since our study did not involve dementia patients, it does not suggest that maitake can treat dementia,” she said.

The researchers do not yet know exactly why the Y10M strain offered neurological benefits while the C5304 strain did not. Both mushrooms share almost identical macronutrient profiles. The scientists suspect that subtle structural differences in their specialized carbohydrates might alter how the body’s digestive system and immune receptors interact with the fungus.

Future investigations will require larger groups of volunteers over longer clinical periods to verify these outcomes. Scientists will also need to test more diverse populations to confirm these dietary benefits extend beyond this specific demographic.

“We aim to reveal the health benefits of mushrooms and to provide mushrooms that help promote health in many people,” Jogi said. “To achieve this aim, we first want to clarify why the effects on cognitive function and immunity differed depending on the maitake strains. Moreover, we will examine how factors related to mushroom ingestion (method, amount, and timing) affect its health benefits, and we want to clarify how these benefits can be enhanced.”

As they continue this line of inquiry, the research team hopes to explore the exact molecular pathways connecting a mushroom-enriched diet to natural killer cell function and long-term brain health in aging adults. They view the fungi as an exciting frontier for natural health interventions.

“We hope that many people will come to know that maitake is a food with great potential,” Jogi said. “We believe that maitake may offer various health benefits beyond cognitive function through immunoregulation, and we intend to reveal its potential.”

Ultimately, they envision their research translating into simple dietary choices that improve patients’ quality of life.

“We would like many people to know that daily ingestion of maitake may reduce the risk of dementia,” Jogi added. “We expect that maintaining healthy cognitive function will also help extend a healthy lifespan.”

The study, “Maitake Mushroom (Grifola frondosa) Enhances Cognitive Function in Healthy Older Japanese: A Randomized, Double-Blind, Placebo-Controlled Trial,” was authored by Eri M Jogi, Masaharu C Kato, Yuki Masuda, Morichika Konishi, Naoko Kuwabara, Shinji Sato, Saori Nakagawa, Kenji Yamasaki, Ryutaro Aoki, Miho Ohno, Shuzo Ohata, Setsushi Kato and Michio Hashimoto.