King Oyster

What it is and how it is named

King oyster mushroom is Pleurotus eryngii, in the family Pleurotaceae, and GBIF lists it as an accepted species name. [3] It is also sold as king trumpet mushroom or eryngii. It belongs to the same genus as the oyster mushroom (Pleurotus ostreatus), but they are different species, and a result for one cannot be assumed for the other. A review of Pleurotus mushrooms describes the genus as widely cultivated and rich in protein, fiber, vitamins and minerals. [4] Nutrient numbers belong on mushroom nutrition, not here.

Traditional use

Proper evidence not found: we read no source describing traditional medicinal use of king oyster mushroom, so none is described. We searched PubMed for the species name and for human studies.

What research shows

Proper evidence not found for long-term human outcomes. We searched PubMed for Pleurotus eryngii with human intervention terms and found one human meal study that fit.

The other papers on this species that our search returned looked, from their titles, like laboratory work (cell studies and polysaccharide chemistry). We read only those titles, so we do not use them, and laboratory work could not tell a reader what eating the mushroom does anyway.

The abstract of the meal study attributes the effect to the mushroom's polysaccharides, but a single trial of this kind cannot establish the reason. A review of all edible mushrooms eaten by people found limited experimental evidence, mostly for triglycerides and an inflammation marker, and rated most of the articles "poor" for quality. [6]

Forms and why the form matters

The trial used a meal. Fresh cooked king oyster, dried slices, powder and extract capsules are different products, and none of those results transfers to another form. See mushroom supplement forms and fresh vs dried mushrooms.

Official statements

Proper evidence not found: we read no regulator statement about king oyster mushroom as a health product.

Lab data and chemistry

This section is about what laboratories have measured in king oyster, not about health effects. A compound listed here was reported in at least one study. That does not mean every mushroom or product contains it, and it does not mean it does anything in your body. For the general explanation of the compound groups, see ergothioneine and other mushroom compounds and beta-glucans vs polysaccharides.

What the laboratory literature reports in this mushroom

Wikidata, which collects "found in this species" statements from published chemistry (the LOTUS initiative), lists 21 compounds for Pleurotus eryngii. [9] None of the 21 entries carries a linked paper in the data we pulled, so we cannot name the study behind each one. We show the ones that stand out. Ergothioneine and beta-glucans are not among the 21 entries, but they are measured in the table further down, so an absent entry only means nobody added it to Wikidata.

Most of the 21 are sterols related to ergosterol, the mushroom's version of cholesterol, which is also the raw material for vitamin D2 when a mushroom is exposed to ultraviolet light. [9] [8]

Measured values

Values from the U.S. Department of Agriculture (USDA) are for 100 g of raw, edible mushroom as sold. The USDA record is a Foundation Foods entry, "Mushroom, king oyster", FDC ID 2003599 (dataset release 2025-12-18). [8] The number of samples is in the USDA record, which we did not open sample by sample.

Where the two beta-glucan sources differ: USDA's 1.95 g per 100 g of fresh mushroom works out, by our own arithmetic from its water content, to roughly 16 g per 100 g of dry matter, against 26 g in the Italian sample. That is a calculation of ours, not a reported value, and the two labs used different samples and methods. We found no open measured value for total triterpenes or for heavy metals in king oyster that we read in full.

What the numbers do and do not mean

• Amounts vary with strain, growing material, harvest and drying. The Italian paper itself says glucan content depends on the strain, the part of the fruiting body and the assay used. [10]
• A measured amount of a compound does not show a health effect. Our page above reports one small meal study, and a lab number cannot tell us what that meal did.
• The ergothioneine in the USDA row is in a food portion. By our own arithmetic it is about 2 mg per g of dry matter, which is at the top of the 0.4 to 2.0 range in [11], but that is our conversion, not a measurement. Whether ergothioneine from mushrooms or from capsules improves health is not established. The one human trial we read on a related species (oyster mushroom, four portions a week for 12 weeks, 80 older adults) reported better delayed word recall and lower anxiety scores than placebo, but it is a different species and the abstract is all we read. [13]
• Fruiting body and mycelium are different materials. The cultured king oyster mycelium in [12] was measured at higher ergothioneine than the fruiting-body range above (the paper's abstract does not state the weight basis), but that was an optimised liquid culture made for the purpose, and a mycelium-on-grain powder is a different product again. See fruiting body vs mycelium.
• "Beta-glucan" on a label depends on the test used. An enzyme-based kit separates beta from alpha glucans, as in [10], while a general polysaccharide test does not.