Ergothioneine: Benefits, Foods and What Trials Show

Quick answer

Ergothioneine benefits, in short: Ergothioneine is a natural compound found in mushrooms and fermented foods, and some researchers think it may matter for healthy aging. The human evidence is very thin. The only placebo-controlled supplement trial we found had just 19 older adults with mild memory problems [1], and a 2025 review says larger, longer trials are still needed [2]. We rate the evidence D: small, early human data, so it is too soon to say it helps.

What is ergothioneine?

Ergothioneine (say “er-go-THIGH-oh-neen”) is a naturally occurring amino acid and antioxidant. People get it from food, mainly mushrooms and fermented foods, and the body takes it in using a dedicated transporter [3]. A 2023 review reports that blood levels fall after about age 60 and that lower levels have been linked to faster memory decline. Those are observational links, which can’t show that low ergothioneine is the cause [3]. This page is about ergothioneine taken by mouth. Skincare products that contain it are a different topic, and we found no verified skin trial.

Which foods contain ergothioneine?

Mushrooms and fermented foods are described as high in ergothioneine [3]. The papers we checked don’t give amounts per serving, so we don’t quote any numbers. That also means we can’t say how a mushroom-rich diet compares with a supplement.

Ergothioneine benefits: what might it help with?

Possible benefit	Rating	In plain words
Memory and learning in older adults with mild memory problems	Early	One 19-person pilot saw better scores on one learning test. It is far too small to be confident [1]
Blood marker of nerve-cell damage (neurofilament light)	Early	It stayed steady with ergothioneine but rose on placebo in the same small trial [1]
Other body systems (heart, eyes, kidneys, skin and more)	Early	Reviews describe possible roles, but we found no trials in people for these, and the 2025 review says larger trials are needed [2]
Living longer or “slowing aging”	Early	No trial has tested this in people. Higher blood levels were linked to lower death rates in observational data, which can’t show ergothioneine is the reason [3]

Ratings describe how good the research is, not a promise that it will work for you.

What the research says

• Pilot trial in older adults with mild memory problems (19 people). Adults aged 60 or older with mild cognitive impairment took either ergothioneine (25 mg capsules) or a placebo three times a week for one year. Blood counts and kidney and liver tests did not change. The ergothioneine group did better on one learning test, and its blood level of neurofilament light (a marker of nerve-cell damage) stayed steady while it rose in the placebo group [1]. The authors declared no conflicts of interest. With only 19 people, this is a pilot and not proof. PubMed · DOI
• 2025 review. It reports that observational studies link low blood ergothioneine with memory problems, heart conditions, frailty and earlier death, and that small trials in older adults suggest possible gains in thinking, memory and sleep. It also says larger, long-term trials are needed to confirm cause [2]. PubMed · DOI
• 2023 review. It describes ergothioneine as an antioxidant that protects cells in lab and animal work, and asks whether it should count as a “conditionally essential” nutrient. That is a question, not a conclusion [3]. PubMed · DOI

The main limits: only one small human supplement trial, no trial in healthy adults, and a lot of the excitement comes from lab work and observational links.

Amounts and how people take it

These are amounts used in studies, not recommendations.

• Trial amount: 25 mg capsules, taken three times a week for one year [1].
• Review on safety: a 2025 review reports no safety concerns at doses up to 25 mg a day [2].
• Timing and forms: the sources we checked don’t give a firm rule.

Side effects, interactions and who should check first

In the one-year pilot, blood counts and kidney and liver tests did not change [1], and the 2025 review reports no safety concerns up to 25 mg a day [2]. Very few people have been studied, so rare effects and interactions with medicines are not known.

Who should check with a doctor or pharmacist first

Check with a doctor or pharmacist first if you:

• take any regular medicine, because we found no interaction data
• are pregnant or breastfeeding, or planning to be, because we found no safety data for this group
• have memory worries, so a doctor can look at the cause rather than you relying on a supplement
• are thinking of more than the amounts used in studies

Ergothioneine vs spermidine

They are different compounds. Both come up in aging research, but we found no trial comparing them, so we can’t say which is better. See our spermidine entry.

Where to buy

Look for the exact name (L-ergothioneine), the amount in mg per serving, and a stated third-party testing certificate you can check. Work out the price per daily dose rather than comparing pack prices.

FAQ

What are the benefits of ergothioneine?

So far, no clear benefit has been shown in people. A small pilot trial of 19 older adults with mild memory problems saw better scores on one learning test [1], and a 2025 review calls for larger trials [2]. We rate the evidence D, so please see it as early and uncertain.

What foods are high in ergothioneine?

Mushrooms and fermented foods are described as rich sources [3]. The reviews we checked don’t give amounts per serving, so we don’t quote numbers. A varied diet that includes mushrooms is a simple food-first option, but we can’t say how it compares with a supplement.

How much ergothioneine do studies use?

The pilot trial used 25 mg capsules three times a week for one year [1]. A 2025 review reports no safety concerns at doses up to 25 mg a day [2]. These are amounts used in studies, not recommendations.

Does ergothioneine have side effects?

In the one-year pilot trial, blood counts and kidney and liver tests did not change [1], and a 2025 review found no safety concern up to 25 mg a day [2]. The trial was very small, so rare effects are unknown. Ask a doctor or pharmacist first if you take any medicine.

Is an ergothioneine supplement worth it?

It is too early to say. The only placebo-controlled trial we found had 19 people [1], and reviewers say larger, longer trials are needed [2]. If you are curious, speak to a doctor or pharmacist first, and don’t expect proven results.

Related pages

• Spermidine: another compound studied in aging research
• Urolithin A: another aging-research compound
• GlyNAC: glycine plus NAC
• Longevity supplements for beginners: where this fits in a beginner’s routine
• All supplements A-Z

Talk to your doctor

This page is for general information and is not medical advice. Speak to a doctor or pharmacist before starting any supplement, especially if you are pregnant or breastfeeding, take any medicine, or have a health condition.

References

We cite only studies and official pages we checked against PubMed, the publisher or the agency’s own site. The A to E evidence grades are explained in our editorial policy. See also our medical disclaimer and affiliate disclosure.

1. 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. PubMed · DOI
2. May-Zhang LS, Cheah IK, Zajac IT, et al. Ergothioneine for cognitive health, longevity and healthy ageing: where are we now?. Proc Nutr Soc. 2025. PubMed · DOI
3. Tian X, Thorne JL, Moore JB. Ergothioneine: an underrecognised dietary micronutrient required for healthy ageing?. Br J Nutr. 2023. PubMed · DOI