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Ergothioneine —
the other sulphur compound
the body concentrates.
Most molecules the body uses are made inside it. Ergothioneine is not — it comes entirely from the diet, and yet the body built a dedicated doorway to carry it into the cell and hold it there. A sulphur-bearing amino acid that sits close to glutathione in the chemistry of the cell, and behaves nothing like it.
I
A molecule the body goes out of its way to keep —
and does not make for itself.
There is a small group of molecules the body handles with unusual care. Ergothioneine is one of them. It is a sulphur-bearing amino acid — a derivative of the amino acid histidine, carrying a sulphur atom on its ring — and it occupies a curious place in human biology. The body cannot make it. No human enzyme synthesises ergothioneine; every molecule of it in the body arrived through the diet, produced originally by fungi and certain bacteria. And yet, despite being a molecule the body does not produce, ergothioneine is one the body has built specific machinery to capture and hold.
That machinery is a dedicated transporter — a protein in the cell membrane whose particular job is to recognise ergothioneine and carry it inside. The transporter is known by the name OCTN1, and the unusual thing about it, in the eyes of the researchers who study it, is its specificity. Cells have many transporters, most of them handling broad families of molecules. A transporter built around a single dietary compound is rare. The existence of OCTN1 is, in a sense, the body's own statement that this particular molecule is worth the trouble of keeping — a statement written in protein rather than words.
This places ergothioneine in interesting company. It sits within the cell's sulphur chemistry, near the molecules this series has been mapping — glutathione above all, but also N-acetylcysteine and the cysteine pool. But where glutathione is made continuously inside the cell and turns over in hours, ergothioneine is gathered from outside and held for a long time. Two sulphur molecules, two completely different relationships with the body. The contrast is the most interesting thing about reading them side by side.
The body does not make ergothioneine.
It builds a doorway to bring it in.
A transporter for a single molecule
is the body's way of saying
this one is worth keeping.
Four facts about the molecule
Four things that make ergothioneine unusual —
its structure, its source, its transporter, and its stability.
Ergothioneine is unlike most molecules in the cellular sulphur economy. The cards below sketch the four features the literature returns to most often.
I
A histidine derivative
The structure · sulphur on a ring
Ergothioneine is built on the amino acid histidine, modified to carry a sulphur atom on its imidazole ring in a form chemists call a thione. The structure is distinct from the open thiol that cysteine and glutathione carry — a different chemistry of sulphur entirely.
II
Entirely dietary
The source · made by fungi, not by us
The body has no enzyme to synthesise ergothioneine. It is produced by fungi and certain soil bacteria and enters the food chain from there. Mushrooms are by a wide margin the richest dietary source, which is why the molecule is sometimes described in the literature as fungal in origin.
III
OCTN1
The transporter · a dedicated doorway
A membrane transporter, OCTN1, recognises ergothioneine and carries it into the cell. Its unusual specificity for a single dietary molecule is the feature researchers point to most — a rare case of the body building dedicated machinery for a compound it does not make.
IV
Long-lived in tissue
The stability · held, not turned over
Once inside the cell, ergothioneine is stable and long-lived — accumulated in certain tissues and held for extended periods, rather than synthesised and degraded continuously. The opposite of glutathione's hours-long turnover described elsewhere in this series.
II
The dedicated transporter —
what it means that the body built a doorway for one molecule.
The discovery of OCTN1 is what moved ergothioneine from a biochemical curiosity to a molecule the field takes seriously. For most of the twentieth century, ergothioneine was a known compound without an obvious role — present in the body, clearly accumulated in some tissues, but with no understood reason for being there. The identification of a transporter built specifically around it changed the question. A body does not generally invest in dedicated machinery for a molecule that does nothing; the presence of OCTN1 implies, at minimum, that ergothioneine matters enough to be worth retaining.
The transporter concentrates ergothioneine in particular tissues — the literature describes notable accumulation in cells exposed to high metabolic demand and in tissues that handle a great deal of cellular chemistry. The pattern of where the body chooses to hold ergothioneine is one of the active areas of the research. It is the kind of distribution map that, read carefully, hints at function — the body tends to keep things where it needs them, and the tissue pattern of ergothioneine has been studied with that logic in mind, much as the turnover and distribution of glutathione has been mapped across the body.
It was this combination of features — dietary origin, dedicated transporter, selective tissue accumulation, long retention — that led one prominent researcher to propose that ergothioneine might belong to a class he termed longevity vitamins: dietary compounds that are not strictly essential in the classical sense, but whose long-term availability may be relevant to healthy ageing. The term is a proposal, framed by its author as a hypothesis rather than a settled fact, and the research that would test it fully is still developing. But it captures why the molecule draws the attention it does. Selenium occupies a similar place in the story — another rare element the body handles with unusual specificity within its sulphur and redox chemistry.
Glutathione is made and remade in hours.
Ergothioneine is gathered and kept for weeks.
Two sulphur molecules,
two opposite relationships with time.
The molecule in numbers
Three observations on ergothioneine —
the source, the transporter, and the retention.
Diet only
Ergothioneine is obtained entirely from food — the body synthesises none of it
No human enzyme produces ergothioneine. The molecule is made by fungi and certain bacteria and reaches the body through the diet, with mushrooms as the richest known source. A compound the body keeps but does not make — an unusual category in human biochemistry.
One transporter
OCTN1 — a membrane protein with notable specificity for this single dietary molecule
The OCTN1 transporter recognises ergothioneine and carries it into the cell. Its specificity for one dietary compound is the feature the literature emphasises — dedicated machinery for a molecule the body does not produce, which researchers read as a sign the molecule is retained on purpose.
Long retention
Once absorbed, ergothioneine is held in tissue for extended periods rather than turned over rapidly
Ergothioneine is stable inside the cell and accumulates in particular tissues, held for long periods. This stands in contrast to glutathione, whose hepatic pool turns over several times a day. The two sulphur molecules sit at opposite ends of the cell's spectrum of molecular time.
III
Ergothioneine in the cellular neighbourhood —
where the fungal molecule sits beside the tripeptide.
To place ergothioneine in the neighbourhood of glutathione is to notice both how close and how different the two molecules are. Both carry sulphur. Both are discussed in the literature in the context of cellular redox biology. Both accumulate in the cell at meaningful concentrations. But the chemistry of their sulphur differs — glutathione's is an open thiol, reactive and quick; ergothioneine's is a ring-bound thione, stable and slow. And their relationships with the body differ even more: one is synthesised within the cell from amino acid building blocks, the other gathered from the diet and conserved. They are neighbours in the way that two very different houses on the same street are neighbours — close in location, distinct in character.
This complementarity is part of why the molecules are sometimes studied together. The research literature has examined the cell's full complement of sulphur-bearing compounds as a kind of interlocking set, each occupying its own chemical niche, each with its own dynamics and distribution. Ergothioneine is one node in that wider network — a molecule the field continues to investigate, with new work appearing regularly on its tissue distribution, its transporter biology, and its place among the dietary compounds relevant to long-term cellular chemistry.
The contemporary Codeage catalogue brings the two molecules together directly. The Liposomal Ergothioneine+ preparation pairs ergothioneine with L-glutathione in a single liposomal format — the fungal molecule and the tripeptide side by side, as they sit in the cellular sulphur economy itself. Alongside the Liposomal Glutathione hero, it is part of the Pillar 03 architecture within the Longevity Code, where the molecules of cellular chemistry are housed as one coherent daily system. The literature on ergothioneine continues to develop; the picture described here reflects the current understanding rather than a closed account. Studies referenced were conducted independently and did not involve any specific Codeage product.
Codeage · Cellular Longevity · Pillar 03
Two sulphur molecules, one format —
from the Pillar 03 line.
The fungal molecule and the tripeptide it sits beside — formulations from the Codeage glutathione line, in formats designed for daily use.
Liposomal Ergothioneine+
A liposomal preparation pairing ergothioneine with L-glutathione — the fungal sulphur amino acid and the tripeptide together in the Helix Liposomal vesicle architecture. The Codeage entry point to the ergothioneine molecule.
View Product →Liposomal Glutathione
The flagship of the Codeage glutathione architecture. Reduced L-glutathione (GSH) supplied in a phospholipid vesicle format — the Helix Liposomal delivery system used in select Codeage formulations. The Pillar 03 anchor of the cellular redox conversation.
View Product →Liposomal NAC
N-acetyl-L-cysteine — the acetylated cysteine derivative — supplied in capsule form within the Codeage liposomal line. A further sulphur-bearing molecule from the same cellular neighbourhood, explored earlier in this series.
View Product →Previously in this series
NAC and Glutathione — How N-Acetylcysteine Connects to the Tripeptide
Codeage · The Longevity Code
The molecules of the cell —
kept within one system.
The cellular pillar of the Longevity Code houses the tripeptide and the sulphur molecules around it within a single coherent daily architecture.
Explore The Longevity Code →
