Oyster mushrooms preserved mood and cut inflammation in older adults

A randomized crossover trial in Food & Function found that a single serving of oyster mushrooms preserved positive mood and cut three postprandial inflammatory markers in healthy older adults, but produced no consistent improvement on any cognitive measure. The study, by Cha and colleagues at the University of Reading, Tufts University, and King’s College London, is the first controlled evidence that acute oyster mushroom intake shifts inflammation markers within hours of a meal. It leaves the cognitive question unanswered.

The OYSACO trial put 33 healthy adults aged 60 to 80 through four test sessions, each a week apart. They ate a noodle soup laced with 0, 0.5, 1, or 2 servings of freeze-dried oyster mushroom. That works out to 0, 40, 80, and 160 grams of fresh mushroom. Each dose supplied a different amount of ergothioneine, a sulphur-containing amino acid that humans cannot synthesize. The body takes it up through a dedicated transporter called OCTN1, which is expressed at high levels in tissues that handle oxidative stress: brain, eyes, bone marrow. Animal and in-vitro work has shown ergothioneine to be neuroprotective and anti-inflammatory, and it is being studied as a possible intervention for cognitive decline.

After the control soup, the group’s positive affect dropped and mental fatigue climbed across the 6-hour window. After any mushroom soup, these shifts disappeared. The effect was not cleanly dose-dependent. All three mushroom doses blunted the mood deterioration seen with the control, but the 1-serving condition produced the sharpest signal across both the positive affect and mental fatigue measures. The researchers used linear mixed modelling with participant as a random factor and baseline scores as a covariate, with Bonferroni correction on the post-hoc tests.

What the study measured

At baseline and at 2, 4, and 6 hours after eating, each participant completed the PANAS-NOW mood scale, a subjective mental fatigue rating, and four cognitive tasks: the Rey Auditory Verbal Learning Task (episodic memory), a task-switching paradigm (executive function), the Corsi Blocks task (visuospatial working memory), and a finger-tapping task (motor speed). Blood was drawn at 6 hours and assayed for glucose, triglycerides, interleukin-6, brain-derived neurotrophic factor (BDNF), and serum polyphenol and ergothioneine metabolites. The team also exposed cultured rat microglial cells to each participant’s serum and measured three inflammation readouts: nitrite, NADPH oxidase 2 (NOX2), and inducible nitric oxide synthase (iNOS).

On cognition, the results went nowhere. Episodic memory, working memory, executive function, motor speed. None showed a consistent dose-response benefit. The authors are clear that this was an acute study, a single meal tracked across a single afternoon. Chronic dosing may be needed to move cognitive endpoints. And with only 32 completers, the study lacked the power to catch subtle effects.

Inflammation: three markers, three drops

The clearest signal was in the inflammatory panel. Serum taken after any mushroom dose drove significantly lower nitrite, NOX2, and iNOS in microglial cells than serum from the control condition. Nitrite is a proxy for nitric oxide production, which climbs with neuroinflammation. NOX2 and iNOS sit upstream of oxidative and nitrosative stress, the low-grade inflammatory signalling tied to age-related cognitive decline. The drop appeared at all three mushroom doses. Forty grams of fresh oyster mushroom was enough.

This lines up with the broader ergothioneine literature. A 2024 double-blind pilot by Yau and colleagues in the Journal of Alzheimer’s Disease found that 25 mg of ergothioneine three times weekly for a year cut a panel of oxidative damage markers in older adults with mild cognitive impairment. Cognitive outcomes in that trial were also mixed. Oyster mushrooms carry roughly 13 mg of ergothioneine per 100 g, which puts the OYSACO doses between 5 and 21 mg. The Yau trial enrolled people with measurable cognitive impairment; the OYSACO cohort was cognitively healthy. That difference may partly explain why neither study found a clean cognitive signal.

BDNF: the unexpected result

BDNF went the wrong way. Instead of rising after mushroom consumption, it dropped, and the drop grew with dose. The difference hit statistical significance at the 2-serving level. Lower circulating BDNF is generally linked to poorer cognitive aging and smaller hippocampal volume, so this is hard to read as anything other than a warning light. The authors say the mechanism is unclear and may reflect a short-term response that does not carry over to chronic exposure. One possibility: the anti-inflammatory effect temporarily alters how BDNF moves between the central nervous system and the periphery. Without cerebrospinal fluid data or a longer follow-up, the finding stays an open question.

Glucose, triglycerides, and interleukin-6 did not differ between conditions. The mushroom soups were well tolerated. Palatability scores matched the control, so the mood difference was not driven by anyone hating the placebo soup.

Where this leaves the evidence on mushrooms and brain health

The OYSACO study is the first randomized trial of whole-food oyster mushroom on cognition and mood in older adults. It joins a small but growing body of human research on mushrooms and the brain. The same group (Cha, Bell, Shukitt-Hale, and Williams) published a 2024 review in Neuroscience & Biobehavioral Reviews that cataloged every human intervention and epidemiological dataset available. Most of the evidence points toward mood and inflammatory pathways, not direct cognitive gains. Epidemiological cohorts have tied higher mushroom intake, one to two servings per week, to lower odds of mild cognitive impairment, but intervention data are still thin.

Nearly every mushroom-cognition trial so far has used lion’s mane (Hericium erinaceus), not oyster mushrooms, and run for 4 to 16 weeks. The OYSACO trial asked something narrower: what happens in the hours after a single mushroom-containing meal? For mood and inflammation, something real. For cognition, not much, at least not acutely.

What this means for someone reading at home

The dose that seems to matter is modest. One serving (80 grams of fresh oyster mushroom, about a large handful) is easy to add to a stir-fry or soup. The mood-stabilizing signal at that dose, plus the inflammatory-marker drop at every dose tested, makes a more practical case for eating mushrooms regularly than for chasing them as a therapeutic supplement. Ergothioneine has to come from food. Mushrooms are the main source. People who eat them often have higher circulating levels; low ergothioneine status has been associated with frailty and cognitive decline in cohorts.

Oyster mushrooms are cheap and widely available compared to lion’s mane or reishi. A 2024 nutrient survey ranked them among the top dietary sources of ergothioneine alongside shiitake and king oyster; button mushrooms had far less. Cooking does not seem to break ergothioneine down, so sauteed oyster mushrooms in a meal should deliver roughly what the freeze-dried powder in the trial did.

Still: this was one meal in 33 healthy people. It says nothing about whether eating oyster mushrooms every day for weeks or months would change any cognitive endpoint that matters. The BDNF result, preliminary as it is, is a reason to watch for replication rather than to draw conclusions. And for anyone hoping for a cognitive boost specifically, this trial does not support that. The mood and inflammation findings are the story.

References

1. Cha S, Bell L, Fisher DR, et al. A randomised controlled study to investigate the cognitive, mood, metabolic and anti-inflammatory effects of acute oyster mushroom intervention in healthy older adults. Food & Function 17:784-795. 2026. https://doi.org/10.1039/D5FO03075G
2. Cha S, Bell L, Shukitt-Hale B, et al. A review of the effects of mushrooms on mood and neurocognitive health across the lifespan. Neuroscience & Biobehavioral Reviews 158:105548. 2024. https://doi.org/10.1016/j.neubiorev.2024.105548
3. Yau YF, Cheah IK, Mahendran R, et al. Investigating the efficacy of ergothioneine to delay cognitive decline in mild cognitively impaired subjects: A pilot study. Journal of Alzheimer’s Disease 102(3):841-854. 2024. https://doi.org/10.1177/13872877241291253