Ergothioneine is a diet-derived sulfur-containing compound that humans absorb and concentrate using a specialized transporter. That unusual biology is established; broad healthy-aging benefits are not.
The short definition
L-ergothioneine—usually shortened to ergothioneine—is a naturally occurring derivative of the amino acid histidine. Fungi and certain microorganisms can make it; humans obtain it from food.
It is often described as an antioxidant, but that label is incomplete. Researchers are also investigating how its chemical stability, cellular transport and tissue distribution may relate to stress responses.
Why the transporter matters
In 2005, researchers identified ergothioneine as the key physiological substrate of the SLC22A4 transporter, historically called OCTN1. This transporter can move ergothioneine into cells much more efficiently than previously proposed substrates.
A dedicated uptake system is biologically interesting, but it does not by itself prove that taking more ergothioneine improves health. Transport explains access—not a clinical outcome.
Where it comes from
Mushrooms are consistently identified as important dietary sources, although content varies substantially by species, growing conditions and measurement method. Some beans, grains and organ meats also contain ergothioneine.
A food-source number without a method, food state and primary citation can be misleading. Our food database therefore publishes quantitative values only after source verification.
What human evidence shows
Human studies establish that oral ergothioneine is absorbed and retained. Observational cohorts have linked lower blood levels with poorer cognitive or functional outcomes, while a very small randomized pilot in adults with mild cognitive impairment reported exploratory signals.
Those results do not show that ergothioneine prevents dementia, reverses aging or extends human lifespan. Larger, replicated trials with prespecified clinical outcomes are needed.
Safety and supplement questions
Published human studies offer some short-term and limited longer-duration safety information, but the evidence base is not large enough to answer every interaction, life-stage or long-term-use question.
There is no universally established optimal supplementation dose for healthy adults. A clinician who knows your conditions, medicines and goals is the right person for personalized advice.
Primary references
- Discovery of the ergothioneine transporter — PubMed ↗
- Human uptake and pharmacokinetics — PubMed ↗
- Dietary sources analysis — PubMed ↗
Reference list last checked Aug. 22, 2026.
Educational information only. This page does not provide personalized medical advice.
Read the full disclaimer →