A long-term study of more than 3,000 middle-aged and older adults found that people who consumed greater amounts of mushrooms performed better on tests measuring short-term and working memory, though researchers cautioned that the findings do not establish cause and effect.
By yourNEWS Media Newsroom.
Regular mushroom consumption was associated with stronger performance on tests of short-term and working memory among middle-aged and older adults followed for approximately a decade, according to research involving Japan’s National Center for Geriatrics and Gerontology.
The observational study followed 3,162 adults participating in a national aging project in Japan. Participants documented their dietary habits through detailed food records, allowing researchers to estimate typical mushroom consumption and compare those eating patterns with cognitive performance over time.
Memory was evaluated using digit span testing, a standard assessment in which participants repeat sequences of numbers in their original order and then repeat other sequences in reverse. The forward portion measures short-term memory and attention, while the reverse task places greater demands on working memory because participants must retain information while mentally rearranging it.
Adults reporting higher mushroom consumption achieved measurably stronger scores on both tests, according to the research team. The relationship remained statistically significant after investigators accounted for numerous factors that could otherwise influence cognitive performance, including age, overall dietary quality, chronic health conditions and socioeconomic circumstances.
The strongest associations emerged among people with moderate to higher levels of mushroom intake.
Researchers nevertheless emphasized an important limitation: The study found an association between eating mushrooms and memory performance but could not demonstrate that mushrooms themselves caused the cognitive differences.
People who regularly consume mushrooms could differ from those who do not in additional lifestyle, dietary or health characteristics that were not completely captured by the analysis. Statistical adjustments can reduce the effects of such differences but cannot eliminate every possible source of confounding in an observational study.
The analysis was conducted collaboratively by government research institutions in Japan and the United States, according to the report, and did not receive funding from the commercial mushroom industry.
The results add to earlier research examining whether mushroom consumption could be associated with healthier cognitive aging. A separate long-term Japanese cohort previously found an association between greater mushroom intake and a reduced risk of developing dementia.
Scientists are particularly interested in mushrooms because they contain several nutrients and naturally occurring compounds that could plausibly affect neurological health.
Among the most closely studied is ergothioneine, an amino acid-derived antioxidant that humans cannot manufacture and therefore must obtain through food. Mushrooms are an especially notable dietary source.
Ergothioneine can cross the blood-brain barrier and accumulate in brain tissue, characteristics that have prompted researchers to investigate whether it could help protect neurons against oxidative stress.
Oxidative stress occurs when unstable molecules contribute to cellular damage faster than the body can adequately neutralize them. Over time, such damage has been implicated in aging and neurological decline, including processes that can interfere with memory and other cognitive functions.
Mushrooms also contain glutathione, another antioxidant, and can provide vitamin D, depending partly on the mushroom and its exposure to ultraviolet light. Both nutrients have separately been investigated in connection with neurological and broader health outcomes.
The researchers did not, however, measure participants’ ergothioneine levels or establish that any particular mushroom compound produced the memory differences observed in the study. The analysis also did not examine individual mushroom varieties separately.
That distinction is important because varieties can differ substantially in their concentrations of ergothioneine and other compounds. Button, shiitake and maitake mushrooms all contain ergothioneine, although the amount can vary considerably between species.
Researchers therefore cannot conclude from this study that one type of mushroom is superior to another for cognitive health.
The study’s decade-long design nevertheless offered researchers an opportunity to examine real-world dietary patterns across a large group of aging adults, something considerably more difficult to reproduce through a lengthy randomized clinical trial.
Interest in such dietary research is increasing as aging populations face rising rates of memory impairment and dementia. Scientists are examining whether long-established lifestyle patterns — including nutrition, physical activity and other modifiable behaviors — could help preserve cognitive abilities before substantial decline develops.
Working memory is particularly important because it allows people to temporarily retain and manipulate information while carrying out everyday mental tasks. It is involved in activities ranging from following instructions and performing calculations to organizing information and making decisions.
The reverse digit span task used in the study is designed to challenge precisely that ability. Rather than simply recalling numbers, participants must hold them in memory and mentally reorder them before responding.
Because participants who consumed more mushrooms performed better on both the forward and reverse portions, the findings point to an association involving short-term retention as well as the more demanding mental processing required for working memory.
The study does not provide a recommended mushroom serving or establish how frequently mushrooms would need to be consumed to produce a cognitive benefit.
Researchers also have not determined whether preparation methods substantially change any potential neurological effects. Light cooking, including a brief sauté, has been suggested as one approach that may retain more nutrients than prolonged boiling, but the current study did not directly test cooking techniques or compare their effects on memory.
For consumers, the research supports mushrooms as one component of a varied diet rather than as a proven treatment or guaranteed method of preventing cognitive decline.
The findings provide another reason for scientists to investigate ergothioneine-rich foods and their potential relationship with brain aging, but controlled research will be necessary to determine whether increasing mushroom intake directly improves memory or reduces the likelihood of cognitive impairment.
Future studies could also help determine whether specific varieties, quantities or preparation techniques are associated with greater effects and whether measurable levels of ergothioneine or other mushroom-derived compounds correspond with changes in cognitive performance.
For now, the decade-long findings add to an expanding body of observational evidence suggesting that dietary patterns — including regular mushroom consumption — may be associated with how well memory and other cognitive abilities are maintained with age.
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