What if one of the most interesting compounds in mushrooms isn't a vitamin, mineral, or conventional antioxidant—but a molecule that the human body has a dedicated system for transporting?
It's called ergothioneine.
Ergothioneine is a sulfur-containing compound derived from the amino acid histidine. It is produced by certain fungi and microorganisms, and mushrooms are among its richest dietary sources.
Humans cannot synthesize ergothioneine themselves.
Yet human cells express a specialized transporter, OCTN1, encoded by the SLC22A4 gene, that facilitates its uptake and retention.
Why would human biology retain a system for absorbing this unusual dietary compound?
That question has attracted growing scientific attention.
What makes ergothioneine unusual?
Laboratory research suggests ergothioneine has antioxidant and cytoprotective properties and may participate in responses to oxidative stress and inflammation.
Researchers are also investigating potential relationships with mitochondrial function, neurological health, and biological aging.
But there's an important distinction between these mechanisms and established human health benefits.
The molecule is biologically interesting. Its ability to prevent disease or extend human lifespan has not been established.
The 2026 mushroom study
One of the more compelling recent investigations involved older adults consuming oyster mushrooms.
In a randomized study published in Food & Function in 2026, investigators enrolled 80 adults ages 60–80. Participants were assigned oyster mushroom powder or a calorie-matched placebo four times weekly for 12 weeks.
Seventy-two participants were included in the analysis.
Researchers reported improvements in delayed memory recall and recognition and favorable differences in some mood measurements in the mushroom group compared with placebo.
This was a whole-mushroom intervention, not a purified ergothioneine trial. Mushrooms contain other nutrients and biologically active compounds, so the improvements cannot be assigned specifically to ergothioneine.
A smaller direct supplementation trial
A 2024 pilot study investigated ergothioneine supplementation in 19 older adults with mild cognitive impairment.
Over one year, participants received ergothioneine or placebo.
Researchers reported encouraging changes in a learning and memory assessment and in a blood biomarker associated with neuronal injury.
The results are preliminary, and a study this small cannot establish clinical effectiveness.
Which mushrooms contain ergothioneine?
Oyster, shiitake, porcini, enoki, and several other mushroom varieties can provide meaningful quantities.
The concentrations vary considerably with species, growth conditions, and processing.
Interestingly, 2026 laboratory research found increased measurable ergothioneine concentrations after certain cooking methods. This may reflect changes in extractability rather than creation of new ergothioneine, and whether it improves absorption in humans remains an open question.
An emerging nutritional frontier
Ergothioneine illustrates an important shift in nutritional science.
Not every biologically valuable dietary compound fits neatly into the traditional categories of vitamins, minerals, fats, carbohydrates, and proteins.
Some compounds may influence how cells respond to physiological stress.
Whether ergothioneine ultimately proves to be a clinically important nutrient remains an unanswered question.
For now, mushrooms offer an interesting dietary source—and a compelling reason to keep studying the molecular biology of food.