Ergothioneine, Vitamin D2 and Other Mushroom Compounds
Ergothioneine, vitamin D2 from UV light, eritadenine and other compounds in mushrooms, with what studies found in people, in animals and in the lab, and where evidence is missing.
Content last updated . This page has not been medically reviewed.
Safety first. Supplements can cause side effects and interact with medicines. Read mushroom safety and interactions before you use any mushroom product.
Ergothioneine
Ergothioneine is an amino acid that also acts as an antioxidant in the lab. A 2023 review says it is found in high amounts in mushrooms and fermented foods, and that humans take it in through a transporter protein in the gut.[2]
How much, and in which mushrooms. A pilot study reports mushrooms contain 0.4 to 2.0 mg per gram of dry weight.[3] Species and growing material change the number. One study of three species grown on different materials found the highest level in Pleurotus citrinopileatus (822.1 mg per kg dry sample), and the substrate mattered.[4] A different study of 14 species found the highest level in shiitake (Lentinula edodes).[5] Different studies measured different species, so no single ranking is reliable.
Do we absorb it? In a pilot study of 10 healthy men, ergothioneine from Agaricus bisporus mushroom powder was taken up into red blood cells after a test meal.[3]
What research shows
| Question | What the source found | Evidence label | Population and form |
|---|---|---|---|
| Antioxidant and protective roles | The review describes a large body of preclinical data pointing to a role as a cellular antioxidant.[2] | Preclinical (cells or animals) | Lab and animal studies |
| Blood levels and aging | Levels decline after age 60, and lower levels are linked to faster cognitive decline in observational data.[2] In a Japanese survey of 1,457 adults, serum levels rose with fish intake as well.[6] | Association only | Observational |
| Pregnancy | In 432 first-time mothers, higher early-pregnancy levels went with fewer pre-eclampsia cases; the authors say an intervention study is warranted.[7] | Association only; no trial | Blood levels, not supplements |
| Memory in mild cognitive impairment | A one-year double-blind pilot (19 people aged 60+) gave 25 mg capsules three times a week versus placebo. Blood counts, kidney and liver markers did not change; a learning test and a nerve-damage marker looked better.[8] | Promising but limited; tiny pilot | Capsules of ergothioneine, not mushrooms |
The review also asks whether ergothioneine should be considered a "conditionally essential" nutrient.[2] That is a question, not a settled finding. Proper evidence not found for supplement safety in pregnancy, breastfeeding or children in the sources we read.
Medicine interaction. In 10 healthy men, a shiitake-rich diet raised plasma ergothioneine for more than 48 hours and modestly increased gabapentin's kidney clearance, with no significant change in total exposure. The authors say diet-drug interactions may occur.[1]
Vitamin D2 from UV light
Mushrooms contain very little vitamin D2 on their own but plenty of ergosterol, which UV light converts to D2.[9] Commercial growers can expose mushrooms to UV after harvest for this purpose. In slices of button mushroom, an artificial UV-B dose gave far more D2 than sun exposure (67.1 versus 3.9 micrograms per gram dry weight), and vitamin D4 formed too.[10] So a mushroom has meaningful vitamin D only if it was UV-exposed; check the label (see mushrooms and vitamin D and foods high in vitamin D).
| Question | What the source found | Evidence label |
|---|---|---|
| Does it raise blood vitamin D? | In 26 young adults with low levels, soup made with UV-B-treated button mushrooms and a vitamin D2 supplement raised serum 25-hydroxyvitamin D similarly over 5 weeks.[9] | Promising but limited; small trial |
| Across trials | A meta-analysis of 6 trials found no significant overall rise, with high heterogeneity. The 3 European trials (average baseline 38.6 nmol/L) showed a rise of 15.2 nmol/L; the 3 US trials (baseline 81.5) showed none.[11] | Mixed |
Sources we read did not measure vitamin D in medicinal-mushroom powders or extracts, so assume nothing about those.
Eritadenine
Eritadenine is a compound in shiitake. A lab study found up to ten times more in four shiitake strains than previously reported for other strains.[12] In rats fed it in the diet for 14 days, it lowered cholesterol in major plasma lipoproteins.[13] Memorial Sloan Kettering says shiitake compounds lower cholesterol in lab studies, but there is no proof from clinical trials that they do so in people.[14] Human trials of eritadenine: Proper evidence not found. A PubMed search for eritadenine with human, participants or trial returned reviews and lab or food-science papers. See shiitake and mushrooms for blood sugar and cholesterol.
Frequently asked questions
Are mushrooms the only source of ergothioneine?
No. The review names fermented foods too, and a Japanese survey found serum levels rose with fish intake.[2][6]
Does ergothioneine prevent dementia?
No source we read shows that. One tiny one-year pilot reported better learning scores, which is promising but limited.[8]
Do UV-exposed mushrooms give vitamin D?
They can. Trials show a rise in blood vitamin D when baseline levels are low, with mixed results overall.[11]
Does shiitake lower cholesterol?
Lab and rat studies suggest eritadenine can, but clinical proof in people is lacking.[13][14]
Is a compound supplement better than the mushroom?
No source we read compared them. Results do not transfer between a food, an extract and an isolated compound.
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Safety note first
Mushrooms eaten as food are different from concentrated compounds sold in capsules. One small study found that a shiitake-rich diet slightly changed how the kidneys cleared the medicine gabapentin, with no change in total exposure (see below).[1] If you take any prescription medicine, ask a pharmacist before adding a compound supplement. See how interactions are classed. Other compounds have their own pages: beta-glucans, hericenones and erinacines, triterpenes in reishi, cordycepin and PSK, PSP and lentinan.
Limits and who should ask first
Compound content varies by species, strain, growing material and method.[4][12] Labeling problems affect functional mushroom products.[15] Ask a clinician if you are pregnant, breastfeeding, giving a product to a child, or have kidney or liver disease, because we found no safety data on isolated compounds for those groups. Tell the surgical team about any supplement.
References
- Effect of mushroom diet on pharmacokinetics of gabapentin in healthy Chinese subjects. British journal of clinical pharmacology. 2014. PubMed 24168107. Read 2026-10-23.
- Ergothioneine: an underrecognised dietary micronutrient required for healthy ageing?. The British journal of nutrition. 2023. PubMed 38018890. Read 2026-10-23.
- The bioavailability of ergothioneine from mushrooms (Agaricus bisporus) and the acute effects on antioxidant capacity and biomarkers of inflammation. Preventive medicine. 2012. PubMed 22230474. Read 2026-10-23.
- On the Identification and Quantification of Ergothioneine and Lovastatin in Various Mushroom Species: Assets and Challenges of Different Analytical Approaches. Molecules (Basel, Switzerland). 2021. PubMed 33805096. Read 2026-10-23.
- Potential role of ergothioneine rich mushroom as anti-aging candidate through elimination of neuronal senescent cells. Brain research. 2024. PubMed 38036238. Read 2026-10-23.
- The Association Between Serum Ergothioneine Concentration and Japanese Dietary Habits: The Third Survey of the ROAD Study. Nutrients. 2025. PubMed 39940375. Read 2026-10-23.
- Relationship between the concentration of ergothioneine in plasma and the likelihood of developing pre-eclampsia. Bioscience reports. 2023. PubMed 37278746. Read 2026-10-23.
- Investigating the efficacy of ergothioneine to delay cognitive decline in mild cognitively impaired subjects: A pilot study. Journal of Alzheimer's disease : JAD. 2024. PubMed 39544014. Read 2026-10-23.
- Bioavailability of vitamin D₂ from UV-B-irradiated button mushrooms in healthy adults deficient in serum 25-hydroxyvitamin D: a randomized controlled trial. European journal of clinical nutrition. 2011. PubMed 21540874. Read 2026-10-23.
- Impact on Vitamin D2, Vitamin D4 and Agaritine in Agaricus bisporus Mushrooms after Artificial and Natural Solar UV Light Exposure. Plant foods for human nutrition (Dordrecht, Netherlands). 2016. PubMed 27323764. Read 2026-10-23.
- Effect of Ultraviolet Light-Exposed Mushrooms on Vitamin D Status: Liquid Chromatography-Tandem Mass Spectrometry Reanalysis of Biobanked Sera from a Randomized Controlled Trial and a Systematic Review plus Meta-Analysis. The Journal of nutrition. 2016. PubMed 26865648. Read 2026-10-23.
- Quantification of the bioactive compound eritadenine in selected strains of shiitake mushroom (Lentinus edodes). Journal of agricultural and food chemistry. 2007. PubMed 17256958. Read 2026-10-23.
- Eritadenine-induced alterations of plasma lipoprotein lipid concentrations and phosphatidylcholine molecular species profile in rats fed cholesterol-free and cholesterol-enriched diets. Bioscience, biotechnology, and biochemistry. 2003. PubMed 12834276. Read 2026-10-23.
- Memorial Sloan Kettering Cancer Center, Integrative Medicine, Shiitake Mushroom (About Herbs, Botanicals & Other Products). Read 2026-10-23.
- Label compliance for ingredient verification: regulations, approaches, and trends for testing botanical products marketed for "immune health" in the United States. Critical reviews in food science and nutrition. 2024. PubMed 36123797. Read 2026-10-23.