Ergothioneine
Summary
Ergothioneine is a dietary antioxidant made by fungi and some bacteria. Human trial evidence is very thin: one year-long pilot in 19 older adults with mild cognitive impairment reported better learning scores and no safety-marker changes. EFSA judged synthetic ergothioneine safe as a novel food at its proposed use levels.
Key facts
- A thio-histidine amino acid made by microbes, especially fungi (including mushrooms) and actinobacteria; plants take it up from soil and people get it from food[3]
- One pilot RCT in 19 older adults with mild cognitive impairment; no large outcome trials[1]
- EFSA set a no-observed-adverse-effect level of 800 mg/kg body weight per day in animal studies and judged synthetic ergothioneine safe at proposed food uses, including in pregnancy[2]
- 25 mg three times a week for a year did not change blood counts, kidney or liver markers[1]
- 1 graded human outcome on this page
- October 11, 2026
How it works
ProposedErgothioneine is taken up into human tissues by a dedicated transporter (SLC22A4, also called OCTN1) and acts as an antioxidant; whether this protects nerve cells in people is unproven.[3][1]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Learning and memory in mild cognitive impairment | Improved | Grade D | Pilot RCT · n = 19 · 2024 Adults aged 60 or older with mild cognitive impairment Form: Ergothioneine capsules · Dose: 25 mg three times a week · Duration: 1 year The ergothioneine group improved on a verbal learning test and plasma neurofilament light (a nerve-damage marker) stayed stable, while it rose on placebo; safety markers did not change. A pilot this small cannot establish benefit. | 39544014 (opens PubMed)Source [1] |
Forms
Studied doses
Doses studied in human trials ranged from a single regimen of 25 mg three times a week (about 75 mg weekly) for one year, in the one pilot trial cited here.[1]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
None found in our sources.
Who should be careful
- Anyone expecting proven benefits
- The only outcome trial cited here is a 19-person pilot.[1]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Where to buy Ergothioneine
Products from brands we partner with that contain Ergothioneine. Listing a product is not a claim that it works; check the amount per serving against the doses studied above, and the label for other ingredients.
- SupersmartPaid linkL-Ergothioneine1 capsule: 5 mg L-ergothioneine (MitoPrime); 30 servings. The pilot trial used 25 mg three times a week (about 11 mg/day averaged), so one daily capsule is about half that on average; human benefit is unproven.Shop at Supersmart (opens in new tab)Price and label checked 2026-10-11 on the brand’s site.
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Frequently asked questions
How much ergothioneine did the trial use?
25 mg three times a week for one year, about 11 mg a day on average.[1]
Does ergothioneine improve memory?
One 19-person pilot in older adults with mild cognitive impairment reported better learning scores; that is far from proof.[1]
Is ergothioneine safe?
EFSA judged synthetic ergothioneine safe at proposed food uses, and a year of 25 mg three times weekly did not change safety blood markers.[2][1]
Is ergothioneine a vitamin?
No. It has no official intake requirement or upper limit; EFSA assessed it as a novel food ingredient.[2]
Sources
- [1]Investigating the efficacy of ergothioneine to delay cognitive decline in mild cognitively impaired subjects: A pilot study. J Alzheimers Dis, 2024. pilot-RCT
- [2]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. review
- [3]The biology of ergothioneine, an antioxidant nutraceutical. Nutr Res Rev, 2020. review
What changed
- New monograph: definition, key facts, evidence table, studied doses, safety and FAQ written from the cited abstracts and fact sheets.
- Review: what-it-is line (histidine origin, fungi and bacteria) and the transporter mechanism are now sourced to a 2020 review.