The Mushroom Nutrient That May Help Protect the Aging Brain

A little-known compound found in mushrooms is attracting serious attention from researchers studying brain health and aging.

It's called ergothioneine.

And a major new study published in Nature Aging found that, among nearly 1,000 blood metabolites examined, ergothioneine had the strongest association with better overall cognition.

The intriguing part? Mushrooms are one of the richest dietary sources of this unusual nutrient.

One variety in particular—the golden oyster mushroom—contains exceptionally high amounts.

But before you start thinking you've discovered an edible Alzheimer's cure, there's an important catch: the research is promising, but it hasn't proved that eating mushrooms prevents dementia.

Here's what we know so far.

A surprising finding in the blood

The 2026 Nature Aging study took a remarkably broad approach.

Researchers examined 991 metabolites in the blood of 1,082 middle-aged adults who did not have dementia. They looked for relationships between these metabolites, cognitive performance and brain MRI measurements.

Fourteen metabolites were significantly associated with general cognition.

Ergothioneine showed the largest effect.

The researchers then looked at independent groups of older adults and found that the association with cognition could be replicated.

They also examined whether the metabolic pattern associated with better cognition corresponded to Alzheimer's disease appearing later in life. In an older Rotterdam Study cohort, blood samples were available from people who subsequently developed Alzheimer's disease as well as people who did not.

The overall metabolic signature associated with better cognition was significantly related to the pattern associated with future Alzheimer's disease.

That doesn't mean ergothioneine was shown to prevent Alzheimer's. But it puts the compound on a much more interesting scientific radar.

So what exactly is ergothioneine?

Ergothioneine is a naturally occurring sulfur-containing compound that humans cannot make for themselves.

It is produced by certain fungi and microorganisms and enters our diet through foods containing it.

Mushrooms are particularly rich sources.

Scientists have known for years that the human body actively absorbs and retains ergothioneine. We even have a specialized transporter—called OCTN1—that is particularly efficient at taking it into cells.

That is unusual.

The body doesn't appear to treat ergothioneine like an incidental food chemical that simply passes through. It actively takes it up and stores it in tissues.

Researchers have proposed that ergothioneine may help protect cells from oxidative stress and inflammation and may have effects on mitochondria and other cellular processes.

But here's another important distinction:

We know ergothioneine has interesting biological properties. We don't yet know exactly what role it plays in preventing human disease.

Much of the mechanistic evidence comes from laboratory and animal research, while human evidence is still developing.

The yellow mushroom connection

If you picture a mushroom, you're probably thinking of a white button mushroom or perhaps a brown cremini.

But one of the richest known sources of ergothioneine is considerably more exotic-looking.

The golden oyster mushroom (Pleurotus citrinopileatus) has a brilliant yellow color and, according to published analyses, can contain substantially more ergothioneine than many common mushrooms.

Other mushrooms are good sources too, including:

• Oyster mushrooms
• Shiitake
• King oyster mushrooms
• Maitake
• Porcini

Even ordinary white button mushrooms contain ergothioneine.

And you don't need to find the golden variety to get the potential benefit. The evidence so far is about ergothioneine exposure, not about one particular mushroom species.

In other words, don't turn this into a hunt for an elusive yellow fungus.

Are mushrooms themselves linked to better brain health?

Interestingly, yes—although again, the evidence isn't definitive.

A 2022 analysis of 2,840 Americans aged 60 and older found that people who consumed more mushrooms performed better on certain cognitive tests, including tests of processing speed and verbal learning.

Several observational studies in Asian populations have also reported associations between mushroom consumption and lower rates of mild cognitive impairment or dementia.

One Japanese prospective study followed older adults and found an association between mushroom consumption and lower dementia risk.

These studies are interesting because they look at the food itself, rather than simply measuring ergothioneine in the blood.

But observational studies have a fundamental limitation: people who eat more mushrooms may differ from people who eat fewer mushrooms in many other ways.

They might eat more vegetables, exercise more, have healthier overall diets or have different socioeconomic circumstances.

Researchers can statistically adjust for some of these factors, but they cannot completely eliminate the possibility that something else explains part of the association.

Now we have some intervention evidence

This is where things get particularly interesting.

A randomized controlled trial published in 2026 gave 80 healthy adults aged 60–80 either oyster mushrooms or a placebo four times per week for 12 weeks.

The oyster-mushroom group showed improvements in measures of delayed verbal recall and delayed word recognition compared with the placebo group.

There were also differences in measures of mood.

That's more informative than an observational study because participants were assigned to the mushroom intervention rather than simply reporting what they normally ate.

But the study was small and lasted only 12 weeks.

It also tested oyster mushrooms—not purified ergothioneine—and therefore cannot tell us whether ergothioneine was responsible for the cognitive effects.

Another randomized trial tested ergothioneine itself in 147 adults aged 55–79 who reported subjective memory problems.

Participants received either 10 mg or 25 mg of ergothioneine daily or a placebo for 16 weeks.

Blood levels of ergothioneine rose substantially in the supplement groups. Some measures of memory and prospective memory improved, particularly with the higher dose, but the results were mixed and the improvement in the primary memory measure was not sustained throughout the study.

Again, intriguing—but hardly a slam dunk.

The longer-term dementia evidence is encouraging

Perhaps the most interesting human evidence comes from a prospective Japanese study involving 1,344 adults aged 65 and older who did not have dementia when the study began.

Researchers measured their blood ergothioneine levels and followed them for a median of 11.2 years.

During that period, 273 participants developed dementia, including 201 cases of Alzheimer's disease.

Higher baseline blood ergothioneine levels were associated with lower subsequent risks of:

• Alzheimer's disease
• Non-Alzheimer's dementia
• Dementia overall

The associations remained after researchers adjusted for numerous cardiovascular, lifestyle and dietary factors.

That's a substantial piece of evidence.

But it remains observational.

It tells us that people with higher ergothioneine levels tended to have lower dementia risk.

It does not prove that raising ergothioneine levels will lower dementia risk.

That's a crucial difference.

What about taking an ergothioneine supplement?

This is where I'd pump the brakes.

Ergothioneine supplements are already available, and human studies suggest that supplemental ergothioneine can substantially raise blood levels.

Short-term studies have also generally found it to be well tolerated at the doses studied.

The FDA has issued "no questions" responses to several GRAS notices involving ergothioneine as a food ingredient.

But safety is not the same thing as proven benefit.

We don't currently have the kind of large, long-duration randomized trial that would allow us to say:

Take X milligrams of ergothioneine every day and you'll reduce your risk of Alzheimer's disease by Y%.

We simply aren't there yet.

And there's another reason to be cautious about jumping straight to supplements: mushrooms contain far more than ergothioneine. They also provide fiber, protein, minerals and numerous other bioactive compounds.

We don't yet know whether the potential benefits of mushrooms come from ergothioneine alone—or from the combination of compounds in the whole food.

An intriguing finding about antacids

The new Nature Aging study produced another finding that deserves attention, although it needs even more confirmation.

Researchers found that people taking antacid medications—particularly proton pump inhibitors (PPIs)—tended to have lower blood levels of ergothioneine.

They also found an association between antacid use and poorer cognition in their middle-aged cohort, with statistical analysis suggesting that lower ergothioneine might account for part of that association.

This does not mean that PPIs cause Alzheimer's disease.

The researchers themselves emphasize that their mediation analysis cannot establish causation.

People taking PPIs may differ from people who aren't taking them in ways that affect both medication use and cognition.

So this is a finding worth investigating—not a reason to stop a prescribed medication.

If you take a PPI or another long-term medication, don't change it because of this study. Talk with your healthcare professional about whether the medication is still appropriate for you.

What should an older adult actually do with this information?

Probably something wonderfully unexciting:

Eat mushrooms.

There's no need to buy an expensive ergothioneine supplement based on the current evidence.

Adding mushrooms to a generally healthy diet is a relatively simple way to increase dietary exposure to ergothioneine while getting the other nutrients and compounds mushrooms provide.

You don't need golden oyster mushrooms, either.

White button, cremini, shiitake, oyster, king oyster and maitake mushrooms can all contribute ergothioneine.

And there's no established "brain-health dose" of mushrooms.

So don't feel as though you need to eat a giant bowl of mushrooms every day.

Think of mushrooms as one small piece of a much larger brain-health puzzle that includes regular physical activity, good cardiovascular health, adequate sleep, a nutritious diet, social engagement and staying mentally active.

The bigger lesson

Perhaps the most interesting part of this story isn't actually the mushroom.

It's ergothioneine itself.

A compound that most people have never heard of is showing up repeatedly in research on aging, cognition and dementia.

The newest study looked at hundreds of metabolites and found that ergothioneine stood out.

Other human studies have linked higher blood levels to slower cognitive and functional decline and lower future dementia risk.

And early randomized trials are beginning to ask the more important question:

If we deliberately increase ergothioneine—or eat more of the foods that contain it—can we actually change brain aging?

We don't know yet.

That's exactly why this is a discovery worth watching.

The Watchdog Takeaway

Mushrooms are not proven to prevent Alzheimer's disease—but the evidence surrounding one mushroom-derived nutrient is becoming increasingly interesting.

Ergothioneine is strongly associated with healthier cognition in several human studies, and mushrooms are among its richest natural food sources. Early intervention research is encouraging, but we still need larger and longer randomized trials before anyone can say that eating mushrooms or taking ergothioneine will prevent dementia.

For now, adding a variety of mushrooms to a healthy diet is a reasonable food choice. Buying an expensive supplement specifically to prevent Alzheimer's is a much bigger leap than the evidence currently supports.