Ergothioneine

L-Ergothioneine

Snapshot

Indications	Contraindications
Cognitive health in ageing¹ Mild cognitive impairment² Neurodegeneration biomarkers² Sleep quality¹ Skin moisture and wrinkles³ Oxidative stress⁴ Ovarian reserve markers⁵	Pregnancy or nursing⁶ Antidepressant medication use⁶ Age under 18⁶

Ergothioneine is a sulfur-containing amino acid derivative made by fungi and certain bacteria, so humans acquire it only through diet⁷. Mushrooms are the predominant dietary source, and tissues take it up through a dedicated transporter, where it acts as an antioxidant and anti-inflammatory compound. People take it to support healthy ageing, chiefly cognition, memory, and sleep quality. Typical users are older adults concerned about cognitive decline, a group in whom blood levels tend to fall⁸. Skin condition is a further use.

Observational data consistently associate low blood ergothioneine with cognitive impairment¹. A small randomized pilot in mild cognitive impairment found improved learning performance and stabilized neurofilament light chain, a marker of neuronal damage². A 2025 observational metagenomic study of older adults found dementia was associated with depleted gut microbial ergothioneine biosynthesis pathways; no trial has tested whether this matters clinically. Products listing ergothioneine are mostly capsules, with a few liquids; see Form comparison.

Per United States product labeling, one label asks anticoagulant users to consult their therapists⁶. The Alzheimer's Drug Discovery Foundation lists the anticonvulsants gabapentin and pregabalin as possible interactions⁸.

Last updated October 16, 2026. Read how we make monographs.

In the full monograph

32 sources, 26 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources