Ergothioneine

What ergothioneine is

Ergothioneine is a derivative of the amino acid histidine, discovered in 1909 in the ergot fungus — hence the name. It is produced only by fungi and some bacteria. Plants cannot make it, animals cannot, humans cannot. Nevertheless, it is found in practically every human tissue.

The body therefore takes it up entirely from food, above all from mushrooms. Contents vary widely: porcini reach over 7 milligrams per gram of dry mass, oyster mushrooms up to 4, shiitake about 1 and button mushrooms around 0.4. 100 grams of fresh button mushrooms thus provide about 3 milligrams, oyster mushrooms and porcini many times that.

Its own transporter

In 2005, a group in Cologne studied a long-known transport protein called OCTN1, which was assumed to channel all kinds of organic cations through cell membranes. When the researchers systematically looked for what it prefers to transport, the answer was clear: ergothioneine, more than 100 times more efficiently than the substances the transporter had been thought to be for.

Cells with this transporter soak up ergothioneine and retain it; cells without it let practically none in. A transport system built for a single substance that the body cannot produce itself is a strong argument that this substance is important. It is not yet an argument that more of it would be better.

The longevity vitamin label

In 2018, the biochemist Bruce Ames took up this argument. His thesis: when supply is scarce, the body first serves the proteins that secure immediate survival and neglects those that protect against long-term damage. He calls the nutrients for this second group longevity vitamins. He lists 10 candidates, with ergothioneine at the very top.

Ames himself writes that these are putative vitamins. He argued; he did not measure. Strictly speaking, a vitamin is only a vitamin if its absence triggers a defined disease — to this day no one has identified an ergothioneine deficiency as a clinical condition.

What the studies show

Malmö 2020 — 3,236 people, 21 years

In the Swedish Malmö cohort, 112 metabolites were measured in the blood of 3,236 participants without heart disease or diabetes, and the group was followed for just over 21 years. Of all 112, ergothioneine was most closely linked to a healthy diet and most clearly to less disease and death. Per standard deviation more in the blood, cardiovascular mortality was 21 percent lower and all-cause mortality 14 percent lower. The authors themselves describe the substance as a biomarker of a healthy diet.

Singapore 2021 — 496 people, brain

A cross-sectional study of 496 people found: the lower the ergothioneine level, the more advanced the cognitive impairment, along with more damage in the white matter. Earlier work by the same group showed that levels fall beyond the age of 60.

Hisayama 2025 — 1,344 Japanese people, 11 years

In the Japanese Hisayama cohort, 1,344 people over 65 were followed for a median of 11 years; 273 developed dementia. The quarter with the highest ergothioneine levels had a 44 percent lower risk of dementia than the quarter with the lowest. It was co-funded by the Suntory group, whose employees measured the blood values.

Pilot study 2024 — 19 participants, one year

The longest intervention study to date: 19 people over 60 with mild cognitive impairment, double-blind against placebo, for one year. The ergothioneine group performed better in a learning test, and a blood marker of nerve damage remained stable, while it rose under placebo. A pilot study with 19 people is an indication, not proof.

Australia 2025 — 147 participants, primary endpoint missed

The largest intervention study to date: 147 people aged 55 to 79 with subjective memory complaints, 16 weeks, against placebo. The primary endpoint, an overall memory score, was not significant. Some secondary measures such as reaction time and falling asleep were. The study was funded by the manufacturer.

Japan 2022 — 92 adults, sleep

In a randomized, placebo-controlled study over 4 weeks in 92 adults with mild sleep complaints, fewer nighttime waking phases occurred; sleep duration and sleep efficiency remained unchanged. The team works at the Suntory group.

Where the data stop

Not a single randomized trial shows that additional ergothioneine extends lifespan or prevents dementia. There are mouse data — in 2024, male mice lived longer on ergothioneine —, but in humans there is as yet no study with a hard endpoint. One is currently underway in Singapore with around 600 participants over 2 years. The observational data cannot replace proof: people who eat a lot of vegetables and mushrooms usually do twenty other things differently as well.

The mechanism, too, is more open than the marketing suggests. In the test tube, ergothioneine is a very good antioxidant. Barry Halliwell, who built up this research field, writes in his 2023 review, however, that the evidence that the antioxidant effect is also its main function in the body is weak. What ergothioneine actually does in the body is therefore unclear — and longevity vitamin remains a hypothesis, not a finding.

Status, approval and legal

Synthetic L-ergothioneine has been authorized in the EU as a novel food since 2017, for food supplements with up to 30 milligrams per day for adults and 20 milligrams for children aged 3 and over. Infants, young children, pregnant and breastfeeding women are excluded from the authorization — not because a risk was found in them, but because the applicant had excluded these groups from the outset. In 2018 the authorization was extended to further food categories. Ergothioneine is not a medicine, and there is no authorized health claim.

Safety

For a substance in this category, the safety situation is unusually good. In the available human studies, no side effects occurred beyond placebo level. Two honest unknowns remain. First, long-term data for high doses are missing: the longest human study ran for one year. Second, variants of the transporter gene are associated with Crohn’s disease and rheumatoid arthritis — what this means for long-term intake, no one knows. Pregnant and breastfeeding women are excluded from the authorization. This is not medical advice.

Sources

• Gründemann et al., PNAS 2005
• Ames, PNAS 2018
• Cheah et al., Antioxid Redox Signal 2017
• Halliwell et al., Annu Rev Food Sci Technol 2023
• Smith et al., Heart 2020
• Wu et al., Free Radic Biol Med 2021
• Meng et al., Psychiatry Clin Neurosci 2025
• Yau et al., J Alzheimers Dis 2024