Ergothioneine is a sulfur-containing compound made by fungi and some bacteria, not by plants or people. You get it from food, mostly mushrooms, and your body holds on to it using a transporter built for it alone. Researchers are interested because of that transporter and because people with higher blood levels in one long Swedish study had lower death rates. Human trials are still small.
Most nutrients that get a "longevity" label have been studied for decades. Ergothioneine is newer to most people, even though it was discovered more than a century ago. Interest picked up in 2005, when German researchers found that humans have a dedicated transporter for it, and again in 2018, when biochemist Bruce Ames proposed it as one of several possible "longevity vitamins." This guide covers what ergothioneine is, which foods have the most, what studies in people have found, and what's still unknown.
Last reviewed: November 2, 2026
Key Takeaways
- Ergothioneine (sometimes written ERG or ET) is an amino acid derivative made by fungi and certain bacteria. Humans can't make it, so all of it comes from food.
- Mushrooms are by far the richest source. Golden oyster, oyster and porcini mushrooms are at the top; common button mushrooms have less but still some.
- The body has a transporter, called OCTN1 or ETT, that pulls ergothioneine into cells and keeps it there for weeks to months.
- In a Swedish study of 3,236 adults followed for about 21 years, higher blood ergothioneine was linked with lower death rates. That kind of study can't show cause and effect.
- Supplement trials so far are small and short. Europe's food safety agency has judged synthetic ergothioneine safe as a novel food.
What is ergothioneine?
Ergothioneine is a small molecule built from the amino acid histidine, with a sulfur atom attached. It was first isolated in 1909 from ergot, a fungus that grows on rye, which is where the name comes from.
Plants don't make it, and neither do animals. Fungi make it, and so do some soil bacteria. Plants pick up a little from the soil, and animals, including us, get it by eating. That's why it shows up in mushrooms in large amounts and in other foods, including meat, in much smaller amounts.
In the lab, ergothioneine acts as an antioxidant and binds certain metal ions. It's also unusually stable compared with many antioxidants. But a 2023 review by Barry Halliwell and colleagues at the National University of Singapore, one of the main groups studying it, made a careful point: its antioxidant effects are well established in test tubes, and the evidence that this is its main job inside the body is weak. The same is true, they noted, for vitamin C and many plant polyphenols. So the honest answer to "what does it do" is that scientists don't fully know yet.
Why do scientists think ergothioneine matters?
The strongest clue is the transporter. In 2005, Dirk Gründemann's team at the University of Cologne showed that a protein called OCTN1 moves ergothioneine into cells more than 100 times more efficiently than the other molecules it was thought to carry. They proposed renaming it ETT, the ergothioneine transporter. Cells that have it build up high levels and hold on to them. Cells without it barely take any in.
Bodies don't usually evolve dedicated machinery for things that don't matter. That's the reasoning behind calling ergothioneine a possible vitamin. Johns Hopkins researcher Bindu Paul has described it as a "stress vitamin," and Bruce Ames put it on his 2018 list of proposed longevity vitamins, alongside carotenoids such as astaxanthin and lutein.
"Proposed" is the key word. No health agency treats ergothioneine as an essential nutrient, and there's no recommended daily intake. Ames's idea is a hypothesis about long-term health in aging, not a settled finding. For background on why aging researchers focus on years lived in good health, see our explainer on healthspan vs lifespan.
Which foods are high in ergothioneine?
Mushrooms, by a wide margin. Penn State researchers measured a range of 0.15 to 7.27 mg per gram of dried mushroom across species, and a 2020 review in Nutrition Research Reviews listed some of the highest.
| Mushroom | Reported ergothioneine (dry weight) | Rough estimate per 100 g fresh |
|---|---|---|
| Golden oyster (Pleurotus citrinopileatus) | About 10.65 mg per g | About 100 mg |
| Porcini (Boletus edulis) | More than 7 mg per g | About 70 mg or more |
| Oyster (Pleurotus species) | Up to about 4 mg per g | Up to about 40 mg |
| Shiitake | About 1 mg per g | About 10 mg |
| White button (Agaricus bisporus) | About 0.4 mg per g | About 4 mg |
The last column is our own rough math, assuming fresh mushrooms are about 90% water. Real amounts vary with the variety, how they were grown and which part you eat. The Penn State team found more in the caps than the stems.
Outside mushrooms, the 2020 review notes that tempeh, a fermented soybean food made with a mold, also contains high levels. Most other foods have far less. Dried porcini are an easy way to add a lot to soups and sauces, since a small handful goes a long way.
What do studies in people show about ergothioneine?
There are two kinds of human evidence: studies that track blood levels in large groups, and small trials that give people ergothioneine or mushrooms.
| Study | Who | What was done | What they found |
|---|---|---|---|
| Smith et al., 2020 (Sweden) | 3,236 adults, median 21.4 years of follow-up | Measured 112 blood compounds at the start, then tracked health records | Ergothioneine was the compound most tied to a health-conscious eating pattern. Each standard-deviation step up in blood level was linked with a 14% lower death rate. Observational only. |
| Cheah et al., 2017 (Singapore) | Healthy adult volunteers | 5 to 25 mg of pure ergothioneine a day for 7 days | Blood levels rose and stayed high; under 4% left in urine. Oxidative damage markers trended lower, but most changes weren't statistically significant. |
| Yau et al., 2024 (Singapore) | 19 adults aged 60 and over in a memory study | 25 mg three times a week, or placebo, for 1 year | Blood counts and kidney and liver markers stayed normal. The ergothioneine group did better on one learning test. Very small pilot. |
| Cha et al., 2026 (UK) | 80 healthy adults aged 60 to 80 | Four portions of oyster mushrooms a week, or a placebo food, for 12 weeks | The mushroom group did better on delayed word recall and recognition, and placebo scores on some mood scales got worse. Tested whole mushrooms, not ergothioneine alone. |
The Swedish study is the one you'll see quoted most. It's large and long, but it measured blood levels once and then watched what happened. People with more ergothioneine in their blood were more likely to follow a health-conscious eating pattern, and probably differed in other ways too. The authors adjusted for many factors, but an observational study still can't show that ergothioneine itself made the difference.
The trials point in an interesting direction and are honest about their limits. They're small, short, and in the mushroom study, people ate a whole food with fiber and many other compounds. If you're curious about the brain side of nutrition research more broadly, our guide to nutrition and cognitive performance covers the bigger picture.
Does ergothioneine help you live longer?
No one has shown that. There's no long-term human trial, and the lifespan question in people would take decades to answer. What exists is a chain of reasoning: the body keeps a dedicated transporter for it, blood levels tend to be lower in older adults in some studies, and higher levels track with longer life in one large observational study. Each link is real. Together they make a hypothesis, not a result.
That's a common pattern in longevity research. Compounds such as NAD precursors and spermidine went through the same arc, with exciting early signals that later trials have been slower to confirm. Our overview of longevity supplements sorts the field by strength of evidence.
Is it safe to take ergothioneine supplements?
What we know so far is reassuring, with the usual caveat that long-term data is limited.
- Regulators. The European Food Safety Authority judged synthetic L-ergothioneine safe as a novel food in 2016, and in 2017 extended its safety conclusion to pregnant and breastfeeding women, infants and young children at the proposed use levels. Its animal safety data found no adverse effects at 800 mg per kg of body weight a day, far beyond any food or supplement intake.
- Human trials. The one-year Singapore pilot reported no changes in blood counts or kidney and liver markers.
- Retention. Because the body keeps ergothioneine for weeks to months, levels build slowly and fall slowly. That's different from water-soluble vitamins you clear quickly.
Doses in trials have ranged from 5 to 25 mg, which is in the same range as a serving of oyster mushrooms. If you take prescription medicine or are pregnant, it's still sensible to check with your clinician before adding any new supplement.
Food or supplement: what makes sense?
For most people, food is the simple first step. A serving of oyster or shiitake mushrooms a few times a week provides ergothioneine along with fiber, B vitamins and other compounds, and the one whole-food trial used exactly that approach. Our guide to diet and longevity covers eating patterns that tend to include mushrooms, beans and whole grains.
If you're looking at a supplement, read the label carefully. Our guide to reading a Supplement Facts label explains the basics. For ergothioneine specifically:
- Check that ergothioneine is listed in milligrams. Some mushroom powders and extracts don't state how much ergothioneine they contain, and the amount varies a lot by species.
- Know the source. Some products use pure L-ergothioneine made by fermentation or synthesis. Others use mushroom extract. Both can be fine; they're just different products.
- Be wary of big promises. Given how early the evidence is, anything sold as an anti-aging fix is getting ahead of the science.
OPA Nutrition doesn't sell an ergothioneine supplement, so this article isn't pointing you to a product.
Frequently asked questions
What does ergothioneine do in the body?
It's taken into cells by a dedicated transporter and kept there for weeks to months, with high levels in red blood cells. In the lab it acts as an antioxidant and binds metals. Researchers are still working out its main role inside the body.
Which foods are highest in ergothioneine?
Mushrooms, especially golden oyster, porcini and oyster mushrooms, followed by shiitake. White button mushrooms have less but still some. Tempeh is also high. Most other foods, including meat, have much less.
Can you take too much ergothioneine?
No upper limit has been set. Animal safety studies found no adverse effects at doses far above what people take, and EFSA judged synthetic ergothioneine safe at its approved use levels. Human trials have used 5 to 25 mg and reported no safety problems.
Is ergothioneine an essential vitamin?
Not officially. Some researchers have proposed calling it a vitamin because the body has a dedicated transporter for it, but no health agency has set a recommended intake, and no one has defined what too little looks like in people.
Is ergothioneine the same as glutathione?
No. Both contain sulfur and both are studied as antioxidants, and some mushroom species are high in both. Your body makes glutathione itself, while ergothioneine has to come from food.
Sources
- Gründemann D, Harlfinger S, Golz S, et al. Discovery of the ergothioneine transporter. Proc Natl Acad Sci U S A. 2005;102(14):5256-5261. PubMed 15795384
- Ames BN. Prolonging healthy aging: longevity vitamins and proteins. Proc Natl Acad Sci U S A. 2018;115(43):10836-10844. PubMed 30322941
- Paul BD. Ergothioneine: a stress vitamin with antiaging, vascular, and neuroprotective roles? Antioxid Redox Signal. 2022;36(16-18):1306-1317. PubMed 34619979
- Halliwell B, Tang RMY, Cheah IK. Diet-derived antioxidants: the special case of ergothioneine. Annu Rev Food Sci Technol. 2023;14:323-345. PubMed 36623925
- Borodina I, Kenny LC, McCarthy CM, et al. The biology of ergothioneine, an antioxidant nutraceutical. Nutr Res Rev. 2020;33(2):190-217. PubMed 32051057
- Kalaras MD, Richie JP, Calcagnotto A, Beelman RB. Mushrooms: a rich source of the antioxidants ergothioneine and glutathione. Food Chem. 2017;233:429-433. PubMed 28530594
- Smith E, Ottosson F, Hellstrand S, et al. Ergothioneine is associated with reduced mortality and decreased risk of cardiovascular disease. Heart. 2020;106(9):691-697. PubMed 31672783
- Cheah IK, Tang RM, Yew TS, Lim KH, Halliwell B. Administration of pure ergothioneine to healthy human subjects: uptake, metabolism, and effects on biomarkers of oxidative damage and inflammation. Antioxid Redox Signal. 2017;26(5):193-206. PubMed 27488221
- 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. J Alzheimers Dis. 2024;102(3):841-854. PubMed 39544014
- Cha S, Bell L, Eastwood J, et al. A randomised controlled study to investigate the cognitive, mood, metabolic and anti-inflammatory effects of chronic oyster mushroom intervention in healthy older adults. Food Funct. 2026;17(12):5621-5633. PubMed 42299921
- EFSA Panel on Dietetic Products, Nutrition and Allergies (Turck D, et al.). Statement on the safety of synthetic L-ergothioneine as a novel food: supplementary dietary exposure and safety assessment for infants and young children, pregnant and breastfeeding women. EFSA J. 2017;15(11):e05060. PubMed 32625352
Disclosure: OPA Nutrition sells supplements, including products mentioned in this article. This content is for education only and is not medical advice. Statements about dietary supplements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease. Talk to your healthcare provider before using any supplement, especially if you take medication or have a medical condition.
