Supplement: Ergothioneine

What It Is

Ergothioneine is a sulfur-containing amino acid, one the human body cannot make. It comes entirely from the diet, and it originates in fungi and certain soil bacteria that build it; plants and animals pick it up from there and pass it along the food chain. Mushrooms are by far the richest source. Levels vary widely by species, from about 0.15 to 7.3 milligrams per gram of dry weight, with specialty mushrooms such as oyster, shiitake, king oyster and porcini at the top and the common white button mushroom lower but still a meaningful contributor. Organ meats such as liver and kidney, black and red beans, and oat bran carry smaller amounts. It is heat-stable, so cooking mushrooms keeps most of it intact.

The name most people meet it under is "the longevity vitamin," a label the biochemist Bruce Ames proposed in 2018 for a small group of diet-derived compounds that may not be strictly essential for survival but could matter for a long, healthy life. That is a hypothesis about ergothioneine, and a reasonable one, held apart from what has actually been measured in people.

What It Does

What has been measured is the level of ergothioneine already circulating in a person's blood, and how that level tracks with their health over the following years. In three separate groups of people, those with more ergothioneine in their blood went on to have lower death rates, less cardiovascular disease, and slower cognitive decline. Alongside that, the body has a dedicated transporter for it and it behaves as an antioxidant in the laboratory, which gives the associations a plausible mechanism, and short human studies have found it safe.

The distinction that runs through all of it: every one of the human findings below is a blood-level association, not a test of taking ergothioneine. Higher levels come with better outcomes, and the level rises with a diet full of the foods that carry it. Each card grades one finding at the strength of its own evidence.

The Research & Studies

Everything here is based on the research we have collected and checked, sorted into groups and ordered with the strongest evidence first. Click any claim to open the studies behind it.

How it works

The body has a dedicated transporter (OCTN1 / SLC22A4) that actively concentrates ergothioneine in tissuesModerate · mixed

In plain terms

Humans have a specific, gene-encoded pump that grabs ergothioneine from food and stores it in tissues, which is why researchers suspect the body needs it for something.

In detail

Ergothioneine is taken up by a specific transporter, OCTN1, encoded by the gene SLC22A4, shown in 2005 to carry ergothioneine with high affinity. The body absorbs it avidly, excretes little (under 4 percent of an oral dose in the urine), and concentrates it in tissues under oxidative stress such as red blood cells, the liver and the lens of the eye. A dedicated transporter is the main argument that ergothioneine plays a physiological role rather than passing through as an inert food component. A dedicated transporter shows the body handles ergothioneine deliberately; on its own it does not prove a health benefit or that supplementing helps.

The study · 1

Grundemann et al., Discovery of the ergothioneine transporter · Proc Natl Acad Sci USA 2005;102(14):5256-5261

Longevity And Mortality

Higher blood ergothioneine tracked with about 14% lower all-cause and 21% lower cardiovascular death per 1 SDPreliminary

In plain terms

Swedish adults with more ergothioneine in their blood were less likely to die, or to develop or die from heart disease, over the next roughly 20 years, about 14 to 21% lower risk for each step up in level.

In detail

In 3,236 Swedish adults free of cardiovascular disease and diabetes at baseline, each 1 standard-deviation higher plasma ergothioneine was associated with a 14% lower risk of death from any cause (hazard ratio 0.86), 21% lower cardiovascular mortality (0.79) and 15% lower risk of coronary disease (0.85), over a median 21.4 years, after adjustment for age, sex, body-mass index, blood lipids, blood pressure, smoking and alcohol. Measured in: 3,236 adults (61% women), mean age 57, from the population-based Malmo Diet and Cancer study, Sweden. What could explain it instead: Ergothioneine was the metabolite most tightly linked to a health-conscious food pattern (fish, vegetables, whole grains), so a higher level may mark a better overall diet and the healthier life around it rather than an effect of the compound. Reverse causation is also possible: early or hidden illness can lower the level, making a low reading look more harmful than it is.. One observational cohort measuring the level already in the blood; nobody was given ergothioneine, so this cannot show the compound caused the lower death rate.

The study · 1

Smith et al., Ergothioneine is associated with reduced mortality and decreased risk of cardiovascular disease · Heart 2020;106(9):691-697

Cognition

Lower plasma ergothioneine predicted faster cognitive and functional decline in older adultsPreliminary

In plain terms

Older adults with less ergothioneine in their blood tended to think and function worse at the start and to slip faster over the following years, across memory and several other mental skills.

In detail

Among 470 older adults attending memory clinics in Singapore, lower plasma ergothioneine at baseline predicted poorer cognition to start and faster decline over follow-up across memory, executive function, attention, processing speed and language, as well as faster functional decline. The longitudinal link held in people who were not yet demented. Measured in: 470 older adults attending memory clinics, Singapore. What could explain it instead: Being unwell lowers ergothioneine, so a low level in a declining person may be a consequence of failing health rather than a cause of it (reverse causation). Diet quality and general health also differ between people with high and low levels.. An observational cohort of people already attending memory clinics; it measured the level, it did not supplement anyone, so it cannot show that raising ergothioneine would slow decline.

The study · 1

Wu et al., Low Plasma Ergothioneine Predicts Cognitive and Functional Decline in an Elderly Cohort Attending Memory Clinics · Antioxidants (Basel) 2022;11(9):1717

A Marker, Not Yet a Medicine

The cohort studies measure the ergothioneine that is already in someone's blood; they do not give it to anyone. That is the whole reason to read them carefully. A higher blood level rises and falls with a diet rich in mushrooms, fish, vegetables and whole grains, the same health-conscious pattern that tracks with lower disease on its own. In the largest study, ergothioneine was the single metabolite most tightly linked to that healthy food pattern. So part of the association between a high level and a longer life may reflect the diet and the life around it, not the compound acting on its own. Illness runs the other way too: being unwell can lower the level, which can make a low reading look like a cause of decline when it is partly a consequence.

The strongest argument that ergothioneine is more than a passenger is biological. The body has evolved a specific transporter that pulls it out of food and concentrates it in tissues, and organisms rarely build a dedicated pump for something inert. That is what makes the longevity-vitamin idea worth taking seriously. It is a reason to keep studying it, not evidence that a capsule extends anyone's life.

What would settle the question is a randomized trial: give some people ergothioneine, give others a placebo, and follow real outcomes over years. That has not been done for lifespan, heart disease or dementia. The human trials that exist are small and short. When purified ergothioneine was given to healthy adults, it was absorbed well and held onto by the body, yet it did not clearly move markers of oxidative damage or inflammation, an early null that may simply mean healthy people have little to correct. Where ergothioneine sits today is as a promising marker with a plausible mechanism and no outcome trial behind it.

How It Works

Anatomy of the Practice

1A dedicated transporter pulls it from food (shown in humans)

Ergothioneine is absorbed and retained by a specific transporter, OCTN1, encoded by the gene SLC22A4, identified in 2005 as its carrier. The body takes it up avidly and excretes very little, under 4 percent of an oral dose in the urine, then concentrates it in tissues under oxidative stress such as red blood cells, the liver and the lens of the eye. This handling is well established in people, and it is the main argument that ergothioneine plays a real physiological role.

2It behaves as an antioxidant and cytoprotectant (mostly cells and animals)

In the laboratory ergothioneine scavenges reactive oxygen species, binds metal ions that would otherwise drive oxidation, and protects cells under stress. This chemistry is well characterized in cells and animal models. How much of it translates into a measurable health effect in a living person is the step that has not been demonstrated.

3It accumulates where the body is under strain (mixed evidence)

Because the transporter is switched on in tissues that face inflammation and oxidative stress, ergothioneine tends to concentrate there, which is why researchers picture it as a stockpiled defense drawn on when needed. The stockpiling is documented; the payoff, whether a fuller stockpile actually protects the tissue over a lifetime, is what the cohorts hint at and no trial has confirmed.

Do It Yourself

Ways to Do It

The richest source is food, and the food is ordinary. Everything with real evidence behind it lives in the free rungs; the supplement is included for completeness, with a plain note on what is and is not known about it.

1

Eat a variety of mushrooms regularlyFreeEasy

Mushrooms are the highest dietary source by a wide margin. Specialty types, oyster, shiitake, king oyster and porcini, carry the most, and the common white button, cremini and portobello have less but still contribute across a week. Variety covers the range, and there is no need to chase exotic species. This is the route behind essentially all of the evidence that ergothioneine tracks with better health, because that evidence comes from people eating food, not taking capsules.

2

Cook them, and eat the whole mushroomFreeEasy

Ergothioneine is heat-stable, so cooking mushrooms keeps most of it, and cooking also makes them easier to digest and safer than raw. There is no special preparation to preserve it: saute, roast, or add them to soups and stews as you normally would.

3

Organ meats and beans as minor sources$Easy

Liver and kidney, and black and red beans, contain smaller amounts and add to the total if they are already part of how you eat. They are a supporting source, not a reason to change your diet, since mushrooms outrank them severalfold.

4

A purified L-ergothioneine supplement$$Easy

Purified L-ergothioneine is sold as a capsule, usually in low milligram doses. What you are buying is a nutrient with a promising marker profile, not a proven benefit: no trial has shown that taking it lengthens life, protects the heart or slows cognitive decline. It is well tolerated at these doses and it is absorbed well. If you try it, treat it as an experiment on top of a good diet, not a substitute for one, and not a substitute for care that has been shown to work.

Go Deeper

• Medicinal mushrooms: the wider tradition and evidence for mushrooms as food and medicine, where ergothioneine is one thread among many.
• Mediterranean diet: the whole-food eating pattern that carries ergothioneine along with everything else linked to a longer life, and why the pattern holds up better than any single isolated compound.
• Dementia: where the cognitive findings fit, and what has and has not been shown to protect the aging brain.
• NMN and NR: another diet-adjacent compound sold for longevity, and a useful comparison for how far a mechanism and marker can carry before trials weigh in.

The Chinese Medicine View

Chinese medicine has no concept of ergothioneine, and reading it into the tradition would be an invention. What the tradition does have is a long use of fungi, both as medicine and as food, and a way of reading their nature that can be laid over the modern compound as interpretation, held apart from the research above.

Several fungi sit in the materia medica with defined roles. Fu Ling (Poria) is a gentle, widely used medicinal that strengthens the Spleen, drains dampness and calms the spirit. Zhu Ling (Polyporus) is a stronger draining diuretic used to move damp accumulation. Ling Zhi (Ganoderma, reishi) tonifies, settles the spirit and is associated with long life in the tradition's own terms. The culinary mushrooms that are richest in ergothioneine belong more to the food category than the pharmacy, valued as nourishing but understood, like all fungi, as carrying a certain dampness.

That is also where the tradition would caution rather than cheerlead. Fungi are read as damp by nature, and rich, moistening foods are understood to burden a person who already tends toward damp or phlegm, feeding the accumulation rather than clearing it. A strongly draining fungus like Zhu Ling is used with care and mainly where there is real dampness to move, since drawing off fluids in someone who is dry or depleted can injure the very reserves the tradition wants to protect. The instinct here is the familiar one, that the right food and the right amount depend on who the person is, which sits beside a modern picture where benefit turns on the whole diet and the individual, not a fixed dose for everyone.

Cautions For This Practice

Extra restraint

Everything to be aware of is here, in one place. This practice suits most healthy people; a few situations call for real care.

A 90-day rat study found no adverse effects at the highest dose, and ergothioneine was not mutagenic

In a 90-day oral toxicity study, Sprague-Dawley rats given up to 1,600 mg/kg/day, the highest dose tested, showed no adverse effects (a no-observed-adverse-effect level at that dose), and ergothioneine was negative in a bacterial reverse-mutation (Ames) test. This toxicology package supports its acceptance as a novel food in Europe and its safe status for food use. An animal toxicology study funded by a supplement manufacturer (Mironova Labs); it speaks to short-term safety, not to any benefit, and long-term safety in people taking a concentrated supplement is untested.Marone et al., A Safety Evaluation of a Nature-Identical L-Ergothioneine in Sprague Dawley Rats

Safe at the doses studied; long-term human safety is unmeasured

Purified ergothioneine has been well tolerated in short human studies and in animal toxicology, and it has been accepted as a novel food in Europe and for food use in the United States. What has not been studied is taking a concentrated supplement for years. Food sources carry no such open question, which is another reason food is the sensible route.

Pregnancy and breastfeeding: get it from food

The transporter for ergothioneine is active in the placenta and the compound concentrates in the developing baby, but supplementation during pregnancy or breastfeeding has not been studied. That absence is a reason to rely on ordinary food sources such as cooked mushrooms rather than a concentrated capsule during these times.

It is not a replacement for treatment that works

Because a high blood level tracks with better heart and brain health, it is tempting to treat a supplement as protection. No trial supports that, so it should not stand in for the measures that do have evidence, from managing blood pressure and cholesterol to the wider diet and activity patterns linked with a long life.

Forage only what you can identify

The advice to eat more mushrooms means cultivated or store-bought ones. Wild mushrooms include species that are poisonous and easily confused with edible ones, and misidentification is the real hazard here, not the ergothioneine. Leave wild foraging to people trained to identify what they pick.

Start slow, be smart, read the research, and consult a professional if you have any concerns. This is here to inform your choice, not make it for you.

Common Questions

Should I take an ergothioneine supplement?

There is no trial showing that it lengthens life, protects the heart or slows cognitive decline, so a supplement buys a nutrient with a promising blood-level profile, not a proven benefit. It is safe and well absorbed at the doses sold. If you want more ergothioneine, the food route is both cheaper and the one the evidence actually rests on: a variety of mushrooms across the week. A capsule is a reasonable experiment on top of a good diet for someone who wants it, provided it does not replace food or proven care.

What foods have the most ergothioneine?

Mushrooms, by a wide margin. Specialty types such as oyster, shiitake, king oyster and porcini carry the most, and common white button, cremini and portobello have less but still contribute. Smaller amounts turn up in organ meats such as liver and kidney, in black and red beans, and in oat bran. Cooking does not destroy much of it, so a normal cooked serving delivers most of what is there.

Is ergothioneine a vitamin?

Not in the classical sense. A vitamin is a compound the body cannot make and needs, where a deficiency causes disease. Ergothioneine is diet-derived and the body cannot make it, and it has a dedicated transporter, which is why it was proposed as a possible "longevity vitamin." What has not been shown is that a low level causes a specific deficiency disease, so the vitamin label is a hypothesis about it, not an established fact.

Does ergothioneine slow aging or prevent dementia?

The evidence today is a set of associations. People with more of it in their blood tend to live longer and to decline more slowly in memory and thinking, and lower levels in older adults predicted faster cognitive decline. None of that shows the compound caused the better outcome, because a high level tracks a healthier diet and general health, and being unwell can lower the level. No trial has tested whether taking ergothioneine changes aging or dementia. It is a marker worth watching, not a demonstrated treatment.

Is it safe?

At the amounts studied, it looks very safe. It is well tolerated in short human studies, a 90-day animal toxicology study found no adverse effects even at the highest dose tested, and it was not mutagenic in a standard genetic test, which is part of why regulators have accepted it as a food ingredient.

The unmeasured part is long-term use of a concentrated supplement, and pregnancy and breastfeeding, where food sources are the sensible route.