Several species of mushrooms, from common grocery store varieties to specialized medicinal fungi, show genuine promise in protecting against cognitive decline. A landmark six-year study from the National University of Singapore found that older adults who ate more than two standard portions of mushrooms per week had 50 percent reduced odds of developing mild cognitive impairment compared to those who rarely ate them. That finding, published in the Journal of Alzheimer’s Disease in 2019, helped ignite a wave of research into how mushrooms affect the aging brain, and the evidence has only grown since. The protective effect appears to be driven largely by a compound called ergothioneine, a unique antioxidant that humans cannot produce on their own and must obtain through diet, with mushrooms being the richest source by far.
Researchers at NUS discovered that plasma levels of ergothioneine were significantly lower in participants with mild cognitive impairment than in age-matched healthy controls, suggesting the compound plays a direct role in brain health. Beyond ergothioneine, specific mushrooms like lion’s mane contain compounds that stimulate nerve growth factor synthesis, which is critical for neuronal repair. This article covers the strongest evidence behind mushroom consumption and brain health, examines the specific species with the most research behind them, explains what ergothioneine does in the brain, and addresses the real limitations of the current science. It also looks at a major new clinical trial that could reshape how we think about mushrooms as a tool for dementia prevention.
Table of Contents
- What Does the Research Actually Say About Mushrooms and Cognitive Decline?
- Ergothioneine — The Brain Compound You Cannot Make on Your Own
- Lion’s Mane — The Mushroom With the Strongest Clinical Evidence
- Which Common Grocery Store Mushrooms Offer Brain Benefits?
- Reishi, Chaga, and Cordyceps — Promising but Mostly Preclinical
- What the Ongoing Clinical Trial Could Mean for Dementia Prevention
- Where the Science Is Heading
- Conclusion
- Frequently Asked Questions
What Does the Research Actually Say About Mushrooms and Cognitive Decline?
The evidence linking mushroom consumption to better cognitive outcomes comes from several population-level studies across different countries. The NUS Singapore study, which tracked more than 600 Chinese seniors over age 60 from 2011 to 2017, remains one of the most cited. Its finding of a 50 percent reduction in mild cognitive impairment risk among regular mushroom eaters was striking, but it was not an isolated result. A 2024 analysis of the EPIC-Norfolk cohort in the United Kingdom found that higher mushroom intake was associated with higher cognitive test scores in older adults. Separately, a study using data from the U.S. National Health and Nutrition Examination Survey between 2011 and 2014 found a positive association between mushroom intake and cognitive performance in older Americans.
These are observational studies, which means they can identify associations but cannot prove that mushrooms directly caused the cognitive benefits. People who eat more mushrooms may also have healthier diets overall, exercise more, or differ in other ways that protect brain health. That said, the consistency of the findings across different populations and dietary cultures is noteworthy. The NUS study, for instance, accounted for age, gender, education, cigarette smoking, alcohol consumption, physical activities, and social activities, and the association still held. A major step toward more definitive evidence is now underway. A 2025 randomized controlled trial protocol published in Frontiers in Aging Neuroscience describes a 600-participant study testing golden oyster mushroom powder, standardized to contain 7.0 milligrams per gram of ergothioneine, against a placebo over 24 months in at-risk middle-aged adults. This is the kind of large, long-duration trial that the field has been missing, and its results could move mushrooms from “promising dietary factor” to a more evidence-based recommendation.
Ergothioneine — The Brain Compound You Cannot Make on Your Own
Ergothioneine is classified as a unique antioxidant and anti-inflammatory amino acid. Unlike vitamins C or E, which the body can recycle or obtain from dozens of food sources, ergothioneine must come almost entirely from dietary intake, and mushrooms contain far more of it than any other food. What makes this compound particularly relevant to brain health is that it accumulates in the brain and appears to counteract several of the pathological processes associated with dementia, including mitochondrial dysfunction, neurotoxin accumulation, and neuroinflammation. The NUS research team specifically measured ergothioneine in participants’ blood and found that those with mild cognitive impairment had significantly lower plasma levels than healthy controls. This does not prove that low ergothioneine caused the cognitive problems — it is possible that the disease process itself depletes the compound — but it does establish a biological link between this mushroom-derived nutrient and brain function.
The body has a dedicated transporter protein for ergothioneine, which is unusual for a dietary compound and suggests it plays an important biological role that evolution has preserved. However, ergothioneine content varies considerably between mushroom species. Oyster, shiitake, and king oyster mushrooms tend to be among the richest sources, while white button mushrooms contain less. cooking methods also matter: ergothioneine is relatively heat-stable, but prolonged boiling can leach it into cooking water. If you are cooking mushrooms in soup, you retain the ergothioneine in the broth. If you are boiling them and discarding the water, you may be losing a meaningful portion.
Lion’s Mane — The Mushroom With the Strongest Clinical Evidence
Among all mushroom species studied for cognitive benefits, lion’s mane has the most direct human clinical data. This shaggy, white mushroom contains hericenones and erinacines, terpenoid compounds that stimulate the synthesis of nerve growth factor, a protein essential for the growth, maintenance, and survival of neurons. No other commonly available food source is known to have this specific mechanism of action. A 49-week randomized controlled trial involving 49 patients with mild Alzheimer’s disease found that lion’s mane mycelia supplements significantly improved scores on the Instrumental Activities of Daily Living scale compared to placebo. An earlier 16-week trial of 30 people with mild cognitive impairment also showed improved cognitive test performance during supplementation.
In healthy young adults, a 2025 study published in Frontiers in Nutrition found that even a single dose of lion’s mane improved reaction time on the Stroop task, a standard test of cognitive processing speed, with 28-day supplementation showing a trend toward reduced subjective stress. Animal research has reinforced these findings: in 15-month-old mice, eight months of lion’s mane treatment prevented cognitive decline and decreased markers of brain inflammation. There is one important caveat that anyone considering lion’s mane should know. In the 16-week human trial, cognitive improvements did not persist after participants stopped taking the supplement. Scores declined back toward baseline once supplementation ended. This suggests that lion’s mane may need to be consumed consistently and over the long term to maintain any cognitive benefit, rather than taken as a short course.
Which Common Grocery Store Mushrooms Offer Brain Benefits?
You do not need to seek out exotic or expensive medicinal mushroom supplements to potentially benefit your brain. The NUS Singapore study specifically examined six commonly consumed mushrooms: golden mushrooms, oyster mushrooms, shiitake, white button, dried mushrooms, and canned mushrooms. All of these were included in the dietary assessment that showed the 50 percent reduced risk of mild cognitive impairment among regular consumers. A standard portion in the study was defined as roughly three-quarters of a cup of cooked mushrooms, and the protective threshold was more than two portions per week. This is worth emphasizing because it means the protective association was observed with mushrooms that are widely available at any grocery store, not with concentrated extracts or capsules. Shiitake and oyster mushrooms tend to have higher ergothioneine content than white button mushrooms, so if you are choosing between varieties, those may offer more of the key compound per serving.
But even white button mushrooms contain ergothioneine and other bioactive compounds including beta-glucans and selenium. The tradeoff between whole mushrooms and supplements is worth considering. Whole mushrooms provide a matrix of nutrients, fiber, and bioactive compounds that work together in ways we do not fully understand. Supplements, particularly lion’s mane extracts, offer concentrated doses of specific compounds and have been the basis for most clinical trials. Neither approach has been proven superior for brain health. If someone dislikes the taste or texture of mushrooms, a supplement may be a reasonable alternative, but it should not replace an otherwise healthy diet.
Reishi, Chaga, and Cordyceps — Promising but Mostly Preclinical
Several other mushroom species are frequently marketed for brain health, but the evidence behind them is substantially thinner than what exists for lion’s mane or common edible mushrooms. Reishi, also known as Ganoderma lucidum, has been used in traditional Chinese medicine for centuries, and preclinical studies highlight its ability to reduce oxidative stress, modulate microglial activity, and support synaptic function. These are relevant mechanisms for neuroprotection, but the studies have been conducted primarily in cell cultures and animal models, not in human clinical trials. Chaga, or Inonotus obliquus, has shown similarly interesting preclinical results. A 2020 review found that chaga extract reduced amyloid-beta accumulation in experimental models, which is significant because amyloid-beta plaques are one of the hallmarks of Alzheimer’s disease.
Cordyceps militaris has been studied for mood-related effects, with a 2025 study finding that a cordyceps formula alleviated depressive behaviors through microglia regulation in an animal stress model. Depression and cognitive decline share overlapping neuroinflammatory pathways, so this is relevant if indirect. The warning here is straightforward: none of these three mushrooms have robust human clinical trial data supporting their use for cognitive decline prevention. Marketing claims often far outpace the science. Someone spending significant money on reishi or chaga supplements specifically for brain protection should understand that they are betting on preclinical promise rather than proven human benefit. The money and effort might be better directed toward eating more common mushrooms regularly, which at least has observational human evidence behind it.
What the Ongoing Clinical Trial Could Mean for Dementia Prevention
The 600-participant randomized controlled trial using golden oyster mushroom powder represents a turning point in this field. Previous human studies on mushrooms and cognition have been limited by small sample sizes, typically between 30 and 50 participants, and short durations. This new trial, described in Frontiers in Aging Neuroscience in 2025, addresses both problems with 300 participants in each arm and a 24-month follow-up period.
The study is using Pleurotus citrinopileatus powder standardized to 7.0 milligrams per gram of ergothioneine, which allows researchers to test a specific, measurable dose of the key bioactive compound. If the trial produces positive results, it would provide the strongest evidence yet that a mushroom-derived intervention can meaningfully slow cognitive decline in people at risk for dementia. If the results are negative or ambiguous, that would also be valuable information, forcing a reconsideration of how much of the observed benefit in population studies is truly attributable to mushrooms versus other dietary and lifestyle factors.
Where the Science Is Heading
The next few years will likely clarify whether mushrooms belong in formal dietary guidelines for brain health or remain in the category of “probably helpful but unproven.” Beyond the golden oyster mushroom trial, researchers are investigating ergothioneine as a standalone supplement, which could separate the effects of this specific compound from the broader nutritional profile of whole mushrooms. There is also growing interest in combining mushroom compounds with other interventions, such as exercise programs or Mediterranean-style diets, to see whether the effects are additive.
What seems increasingly clear is that the research has moved well past the point of being dismissible. Multiple population studies across different countries, a plausible and well-characterized biological mechanism in ergothioneine, and preliminary clinical trial results with lion’s mane all point in the same direction. For families dealing with cognitive decline or worried about dementia risk, adding mushrooms to the weekly diet is a low-risk, low-cost step that aligns with the best available evidence, even as we wait for the definitive trials to report their findings.
Conclusion
The evidence connecting mushroom consumption to cognitive protection is built on a consistent body of observational research, a compelling biological mechanism centered on ergothioneine, and early clinical trial results that show measurable benefits for specific species like lion’s mane. The NUS Singapore study’s finding that eating more than two portions of common mushrooms per week was associated with a 50 percent reduction in mild cognitive impairment risk remains one of the most striking dietary findings in dementia research. Supporting data from the EPIC-Norfolk cohort and U.S. NHANES analyses reinforce the pattern across populations. At the same time, intellectual honesty requires acknowledging what we do not yet know.
Most clinical trials have been small and short. Benefits from lion’s mane supplementation may not persist after stopping. And for reishi, chaga, and cordyceps, the evidence remains almost entirely preclinical. The ongoing 600-participant, 24-month randomized trial of golden oyster mushroom powder could provide the rigorous evidence this field needs. In the meantime, regularly including mushrooms in your diet — particularly shiitake, oyster, and lion’s mane varieties — is a practical, well-supported step that carries essentially no downside for brain health.
Frequently Asked Questions
How many mushrooms do I need to eat per week for potential brain benefits?
The NUS Singapore study found that more than two standard portions per week, with each portion being roughly three-quarters of a cup of cooked mushrooms, was associated with a 50 percent reduced risk of mild cognitive impairment. This is a reasonable target based on the best available evidence.
Are mushroom supplements as effective as eating whole mushrooms?
Most clinical trials on cognitive benefits have used mushroom extracts or powders, particularly lion’s mane, while the large observational studies measured whole mushroom consumption. Both approaches have supporting evidence, but they have not been directly compared. Whole mushrooms provide additional nutrients and fiber that supplements do not.
Does cooking mushrooms destroy the brain-protective compounds?
Ergothioneine is relatively heat-stable, so cooking does not eliminate it. However, boiling mushrooms and discarding the cooking water can leach ergothioneine out. Sautéing, grilling, or using mushrooms in soups where the broth is consumed are better options for retaining the compound.
Can lion’s mane reverse existing dementia symptoms?
A 49-week trial showed that lion’s mane mycelia improved daily living function scores in patients with mild Alzheimer’s disease, and a 16-week trial showed cognitive improvements in people with mild cognitive impairment. However, these were small studies, and in one trial benefits did not persist after supplementation stopped. Lion’s mane should not be considered a proven treatment for dementia.
Are reishi and chaga mushrooms good for brain health?
Reishi and chaga have shown neuroprotective effects in laboratory and animal studies, including reducing oxidative stress and amyloid-beta accumulation. However, there is very limited human clinical data for either species specifically related to cognitive decline. Their brain health benefits in humans remain unproven.
Is ergothioneine available as a standalone supplement?
Ergothioneine supplements do exist and are commercially available. However, most of the human evidence linking ergothioneine to cognitive protection comes from studies of whole mushroom consumption, not isolated supplements. The ongoing 600-participant clinical trial is using mushroom powder standardized for ergothioneine content, which may help clarify whether this compound alone is responsible for the observed benefits.
