Ergothioneine

Evidence Fact Sheet

L-Ergothioneine · EGT

Ergothioneine (L-EGT) is a mushroom-derived dietary antioxidant taken up by a dedicated OCTN1/SLC22A4 transporter and accumulated in tissues. Human evidence is emerging: a large cohort links higher plasma EGT to lower cardiovascular mortality, while early cognition and skin RCTs are small, with honest null findings in acute and biomarker studies.

Also known as: L-Ergothioneine · EGT · ERGO · 2-mercaptohistidine trimethylbetaine

Overview

Ergothioneine (L-ergothioneine, EGT) is a naturally occurring sulfur-containing amino-acid antioxidant concentrated in mushrooms and taken up by a dedicated transporter (OCTN1 / SLC22A4) that lets it accumulate and be retained in tissues including brain, blood cells and skin. Proposed mechanisms studied in preclinical models include scavenging of singlet oxygen, peroxynitrite and hydroxyl radicals, transition-metal chelation, and activation of the NRF2 antioxidant pathway. In research it is explored as a cellular antioxidant and in cognitive, cardiovascular-cohort, and skin contexts; human interventional trials are only recently maturing and remain small. Typical research doses fall in roughly the 5–30 mg/day range, with cognition pilot work around 25 mg/day. Regulatory status: US FDA GRAS self-affirmed (not FDA approval) for synthetic L-EGT and EU Novel Food authorized with an adult ceiling of 30 mg/day (no authorized health claim); not approved as a purified supplement constituent in China or Brazil as of 2026.

Mechanism of Action

Selective scavenging of singlet oxygen / peroxynitrite / hydroxyl radical (research-context · rate constant ~10^6 M^-1 s^-1 for ONOO-) · Transition-metal chelation (Fe2+/Cu2+ pro-oxidant deactivation) · NRF2-ARE antioxidant pathway activation (preclinical) · Mitochondrial DNA / cardiolipin protection (preclinical) · NF-kB / NLRP3 inflammatory-pathway suppression (in vitro / animal) · Autophagy / mitophagy modulation (emerging preclinical)

Body systems: Mitochondrial & Cellular Energy · CNS · Cellular Renewal · Immune System · Skin & Connective Tissue · Cardiovascular

Evidence-Based Benefits

Each benefit below is anchored to a specific PubMed-indexed study. Effect sizes, sample sizes, and p-values are reported as published; no values are inferred. Honest negatives and null results are kept alongside the positive findings, and disease-research populations are described as such — Ergothioneine is not characterized as a treatment for any disease.

Cardiovascular Disease & Mortality (Cohort Association)

Emerging / indexed

HR 0.85coronary disease · p=0.01
HR 0.79CV mortality · p=0.002
3,236cohort · median 21.4 yr

In a large Swedish prospective cohort followed for over two decades, higher blood ergothioneine was the diet-related metabolite most strongly associated with a healthy-cardiometabolic dietary pattern and with lower risk of coronary disease, cardiovascular death, and overall mortality. This is an observational association in people, not evidence that supplementation lowers risk.

Reported effect: HR per 1 SD increment: coronary disease HR=0.85 (p=0.01); cardiovascular mortality HR=0.79 (p=0.002); overall mortality HR=0.86 (p=4e-5); 3,236 participants, median follow-up 21.4 years

“Ergothioneine was the metabolite most strongly connected to the HCFP and was associated with a lower risk of coronary disease (HR per 1 SD increment of ergothioneine, HR=0.85, p=0.01), cardiovascular mortality (HR=0.79, p=0.002) and overall mortality (HR=0.86, p=4e-5).”

Source: PMID 31672783 · Smith 2020 · Heart

Cognition & Age-Related Neurodegeneration (Systematic Review)

Meta-analysis supported

A systematic review of 19 studies concluded ergothioneine is a candidate worth exploring for cognition and age-related neurodegenerative disease, with proposed antioxidative, anti-inflammatory and antisenescence mechanisms. It is review-level evidence describing direction only; no pooled quantitative effect size was reported, so this is a hypothesis-generating signal rather than proof.

Effect size: this study reports the direction of the finding but does not state a specific numeric effect size, so none is given here rather than estimated.

“ET is a potential compound to be explored as its role in cognition and ARND have been discovered through several studies. Mechanisms of ET in improving cognitive function and preventing ARND were found to be through its antioxidative, anti-inflammatory and antisenescence properties.”

Source: PMID 40249478 · Takhor 2025 · Inflammopharmacology

Cognition in Mild Cognitive Impairment (Pilot RCT)

RCT supported

1 yrduration

In a one-year pilot randomized trial in mild cognitively impaired subjects, the ergothioneine group showed improved learning-test performance and stabilized plasma neurofilament light chain (a neuronal-damage marker), while placebo did not improve and saw a significant rise in neurofilament. The abstract reports direction only and no effect-size statistic; with just 19 subjects this is preliminary and needs confirmation in larger trials.

Effect size: this study reports the direction of the finding but does not state a specific numeric effect size, so none is given here rather than estimated.

“Subjects receiving ergothioneine demonstrated improved performance in assessment of learning ability and stabilized plasma levels of neurofilament light chain, compared with the placebo group, which saw no improvement in cognitive assessments and a significant increase in neurofilament light chain levels.”

Source: PMID 39544014 · Yau 2024 · J Alzheimers Dis

Acute Oyster-Mushroom Intervention & Cognition (RCT, Honest Null)

Null / no benefit RCT supported

33participants · cross-over
mixedcognition · no pattern

A randomized cross-over study in 33 healthy older adults gave graded servings of ergothioneine-rich oyster mushroom and found mixed cognitive results with no consistent pattern; mood and some inflammatory markers were maintained or lowered. This is an honest negative for acute cognitive benefit and tempers expectations that a single dose sharpens thinking.

Reported effect: Cognitive findings mixed with no consistent pattern across interventions; 33 participants, randomized cross-over, four occasions

“Cognitive findings were mixed with no consistent pattern of effects seen following OM interventions compared to OM0. Overall, OM interventions helped maintain mood and lower inflammatory markers in healthy older adults, following acute supplementation.”

Source: PMID 41416984 · Cha 2026 · Food Funct

Skin Moisturizing & Facial Condition (RCT)

RCT supported

80women · 25 mg/day · 12 wk
4.7-foldplasma EGT vs baseline

In a 12-week randomized, double-blind, placebo-controlled trial of 80 healthy women, an ergothioneine-rich Pleurotus (25 mg EGT/day) raised plasma EGT 4.7-fold and significantly improved skin moisture content as well as wrinkle and texture scores versus placebo. The effect is for an oral mushroom-based product in women, not a clinical dermatology treatment claim.

Reported effect: 80 healthy women (hiratake n=39, placebo n=38), 25 mg ergothioneine/day for 12 weeks; plasma EGT 4.7-fold higher than baseline (3.4 to 15.9 μM); significantly higher skin moisture at 8 wk and better wrinkle/texture scores at 12 wk vs placebo

“At 12 weeks, wrinkle and texture scores were significantly better in the hiratake group than in the placebo group. ... Plasma EGT concentrations in the hiratake group were 4.7-fold higher than baseline (from 3.4 to 15.9 μM).”

Source: PMID 38887673 · Hanayama 2024 · Front Med

Oxidative-Damage & Inflammation Biomarkers in Healthy Humans (Honest Null)

Null / no benefit Emerging / indexed

<4%urinary excretion of dose
non-significantmost biomarker changes

When pure ergothioneine was given orally to healthy human subjects, it was avidly absorbed and retained with low urinary loss, and biomarkers of oxidative damage and inflammation (urate oxidation, DNA damage, lipid peroxidation, protein carbonylation, CRP) showed only decreasing trends. Crucially, most of these changes were non-significant — an honest negative showing strong tissue retention does not translate to a proven biomarker effect in healthy people.

Reported effect: Low urinary excretion (<4% of administered ET); decreasing trends in oxidative-damage and inflammation biomarkers but most changes non-significant

“After ET administration, some decreasing trends were seen in biomarkers of oxidative damage and inflammation, including allantoin (urate oxidation), 8-hydroxy-2'-deoxyguanosine (DNA damage), 8-iso-PGF2α (lipid peroxidation), protein carbonylation, and C-reactive protein. However, most of the changes were non-significant.”

Source: PMID 27488221 · Cheah 2017 · Antioxid Redox Signal

Dosage (research context · not a recommendation)

5-15 mg/day general antioxidant context (Cheah 2017 PK · OCTN1 saturates ~5 mg/d); cognition research context 25 mg/d ≥12 wk (Yau 2024 pilot RCT 25 mg/d in MCI); EU EFSA Novel Food regulatory ceiling 30 mg/day for adults

Regulatory Status · 4 Markets

US · FDA: US FDA — GRAS self-affirmed no-objection (synthetic L-EGT): Blue California ErgoActive GRN 734 (no-questions 2019); Tetrahedron MitoPrime (2021). Marketed as DSHEA dietary supplement + food fortification. GRAS self-affirmation is NOT FDA approval/certification.
EU · EFSA: EU — Novel Food authorized for synthetic L-ergothioneine (Decision EU 2017/1281 Tetrahedron; Reg EU 2018/462 extension; Union List Reg 2017/2470). EFSA 2016/2017 safety opinions. Adult ceiling 30 mg/day; food-supplement use; NOT recommended for pregnant/lactating women or children <3 yr. NO authorized health claim under Reg 432/2012 (market access only, ≠ functional claim).
CN · China: China: purified synthetic L-ergothioneine not in health-food catalogue nor approved as novel food (no approval as of 2026), not a food additive; only edible-mushroom-source natural EGT is legal as general food; purified EGT supplement has no compliant domestic route (cross-border only).
BR · ANVISA: Brazil ANVISA — NOT listed in IN 28/2018 Anexo I authorized constituents; no dedicated novel-ingredient pathway for purified EGT (case-by-case evaluation). Edible-mushroom extract (whole-food) permissible as traditional food; purified synthetic EGT not authorized as supplement constituent.

Safety

EU EFSA Novel Food adult ceiling 30 mg/day. NOT recommended for pregnant/lactating women or children under 3 years (EFSA — insufficient data). OCTN1 (SLC22A4) is shared with organic-cation drugs (metformin, cimetidine, verapamil) — theoretical competitive-absorption interaction; advise consulting a physician if co-medicated (HARD R5). Reproductive/genotoxicity safety: Forster 2015 reproductive-safety evaluation + Ames/chromosome/micronucleus negative; 90-day rat NOAEL high (FDA GRAS dossiers). Generally well tolerated in healthy-human PK/pilot studies with no significant adverse events reported.

Goals: longevity-stack · cognitive-support

Lifestyles: senior-60-plus

References

PubMed-indexed citations anchoring the benefit findings above. Effect sizes are reported as published.

PMID 31672783 · Smith 2020 · Heart — Cardiovascular Disease & Mortality (Cohort Association)
PMID 40249478 · Takhor 2025 · Inflammopharmacology — Cognition & Age-Related Neurodegeneration (Systematic Review)
PMID 39544014 · Yau 2024 · J Alzheimers Dis — Cognition in Mild Cognitive Impairment (Pilot RCT)
PMID 41416984 · Cha 2026 · Food Funct — Acute Oyster-Mushroom Intervention & Cognition (RCT, Honest Null)
PMID 38887673 · Hanayama 2024 · Front Med — Skin Moisturizing & Facial Condition (RCT)
PMID 27488221 · Cheah 2017 · Antioxid Redox Signal — Oxidative-Damage & Inflammation Biomarkers in Healthy Humans (Honest Null)

Frequently Asked Questions

1. What is ergothioneine and where does it come from?

Ergothioneine (L-EGT) is a sulfur-containing amino-acid antioxidant that humans cannot make; we obtain it from the diet, especially mushrooms. A dedicated transporter (OCTN1 / SLC22A4) takes it up and concentrates it in tissues such as blood cells, brain and skin, where preclinical work suggests it scavenges reactive oxygen and nitrogen species and engages the NRF2 antioxidant pathway.

2. Does ergothioneine improve memory or protect the brain?

The human evidence is early and mixed. A systematic review of 19 studies frames it as a candidate worth exploring, and a one-year pilot RCT in 19 mild-cognitive-impairment subjects reported improved learning performance and stabilized neurofilament light chain. But a randomized cross-over study in 33 healthy older adults found mixed cognitive results with no consistent pattern after acute oyster-mushroom intake. These are research findings, not a treatment for any cognitive disease.

3. What did the cardiovascular research actually show?

In a 3,236-person cohort followed a median of 21.4 years, higher blood ergothioneine was associated with lower risk of coronary disease (HR 0.85), cardiovascular mortality (HR 0.79) and overall mortality (HR 0.86). This is an observational association tied to a healthy dietary pattern — it does not prove that taking an ergothioneine supplement lowers cardiovascular risk.

4. Is ergothioneine safe, and how is it regulated?

Across the human studies reviewed it was generally well tolerated. Regulatory status varies: synthetic L-EGT is GRAS self-affirmed in the US (not the same as FDA approval) and EU Novel Food authorized with an adult ceiling of 30 mg/day and no authorized health claim; it is not recommended for pregnant or lactating women or young children, and is not approved as a purified supplement constituent in China or Brazil as of 2026. This page reports evidence and is not medical or dosing advice.

Last evidence review: 2026-06-13

← Evidence library