Ergothionein Simply Explained

1. What It Is About

Ergothioneine is a natural sulphur-containing substance. Certain fungi, bacteria and other microorganisms produce it themselves. The human body cannot make it. We take it in through food, mainly from mushrooms such as button mushrooms, but also from cereals, meat and fish. In the body ergothioneine accumulates where much work is done and much oxygen is consumed, for example in the liver, the kidney, the bone marrow and the lens of the eye. A dedicated transport pathway carries the substance into the cells. Specialists call it OCTN1. Because the body does not produce ergothioneine itself, its amount in the blood depends on how much we absorb. It is well absorbed from mushrooms. It remains in the blood for a long time, namely about 30 days. It is measured by a complex laboratory analysis, HPLC-MS/MS. Inside cells the concentration is often higher than in the blood.

2. What Studies Show

The best studied aspect is how ergothioneine enters the body. In a small study with 10 healthy men the participants absorbed ergothioneine from button mushrooms. The substance could afterwards be detected in the red blood cells 8. Another study over 7 days showed: the blood level rose markedly and no harmful breakdown product called TMAO was formed 5. This is an important safety question because TMAO has been linked to cardiovascular risks. A 2025 study examined sleep. The participants took it for 16 weeks and afterwards reported better sleep. Objective measurements were not performed, however 2. A study in older adults tested oyster mushrooms for 12 weeks. The participants recognised words better in a memory test and felt less anxious 3. Another study with 33 older adults examined a single mushroom meal. After the meal some inflammatory markers in the blood were lower than after a placebo 4. Whether these effects really come from ergothioneine or from other mushroom constituents is therefore not clarified. An observational study with more than 3000 participants found an association between higher ergothioneine levels and fewer cardiovascular events 6. Another observational study found lower ergothioneine levels in dementia patients than in healthy older people 7.

3. What Remains Unclear

Most human studies are small and last only a short time. There are only few controlled studies in which one group received the substance and another received a placebo. Long-term studies over many months or years are missing. The correct amount is also unclear. Usually only one or two doses were tested. Ergothioneine was almost always given as a mushroom extract. Whether the substance acts alone or only together with other mushroom components is therefore open. The observed associations with cardiovascular disease and dementia do not indicate whether ergothioneine can prevent these diseases. Studies that follow the disease course over a long period would be needed. Such studies are still outstanding. A planned study in people with metabolic syndrome is intended to provide more clarity, but results are not yet available 1.

4. What This Means in Everyday Life

Ergothioneine is a well-researched substance with a clear dietary uptake route. Mushrooms are a good source. That the substance rises measurably in the blood and accumulates in cells is well documented. That it is not converted to TMAO is also a robust finding. The hints of better sleep, better mood or less inflammation are interesting but not yet confirmed. They come from small studies and the contribution of other mushroom constituents cannot be excluded. Anyone interested in ergothioneine will find a natural source in mushrooms. What is missing are large, long-term human studies that demonstrate clear health benefits. Until then ergothioneine remains an intriguing substance with many open questions.

All Details with Study Numbers and Sources: detailed page on ergothioneine. For children: ergothioneine for children.