King trumpet mushroom (Pleurotus eryngii) is a large, meaty-textured mushroom in the oyster mushroom family. It is low in calories and fat, contains measurable amounts of ergothioneine and beta-glucans, and has been studied in a small number of human trials for its effects on digestion and post-meal blood sugar. Most of the research on this specific species is still limited compared to shiitake or reishi, so this guide separates what has been tested in people from what has only been shown in the lab.
A quick safety note before the details: people who are pregnant, are 65 or older, or have a weakened immune system should make sure any mushroom, including king trumpet, is cooked thoroughly. Processing-plant surveys have found Listeria monocytogenes present in some king oyster mushroom production facilities, and these groups are at higher risk of serious illness from that bacteria. More on this below.
Where the Name Comes From
King trumpet is also sold as king oyster mushroom, French horn mushroom, eryngi, or trumpet royale. It is native to Mediterranean Europe, the Middle East, and North Africa, where it grows near the roots of sea holly (Eryngium) plants and, in one variety, near the roots of giant fennel (Ferula) plants. It is the largest species in the Pleurotus genus, which also includes the common oyster mushroom. Today it is grown commercially across Asia, Europe, and North America, with large-scale cultivation in China and South Korea.
Nutrition Facts
The United States Department of Agriculture’s FoodData Central database does not currently list a species-specific entry for king trumpet mushroom (Pleurotus eryngii). USDA data exists for the common oyster mushroom (Pleurotus ostreatus), a close relative, and researchers use that as a general reference point for the genus. For king trumpet specifically, the most detailed figures come from peer-reviewed proximate-composition studies rather than the USDA database.
Published analyses of raw king trumpet mushroom report the following general pattern per 100 grams:
- Moisture: roughly 89 to 93 percent, consistent with most fresh mushrooms.
- Protein: roughly 2.6 to 2.9 grams, similar to or slightly higher than common oyster mushroom.
- Fat: very low, generally under 0.5 grams.
- Minerals: potassium is consistently the highest mineral by weight, followed by phosphorus, magnesium, and sodium.
- Vitamins: a comparative study of mushrooms commonly eaten in Korea found king trumpet’s vitamin content was highest in ergosterol, followed by niacin (B3), vitamin C, thiamine (B1), folate, and vitamin B12, and that king trumpet contained more of most of these vitamins than common oyster mushroom, with thiamine as the one exception.
Like other cultivated mushrooms, fresh king trumpet grown in dark commercial growing rooms is naturally low in vitamin D2. Mushrooms contain ergosterol, a compound that converts to vitamin D2 when exposed to ultraviolet light. Research on related Pleurotus species shows that mushrooms grown without UV exposure typically have less than 1 microgram of vitamin D2 per 100 grams fresh weight, while deliberate UV-B treatment after harvest can raise that substantially. Whether a specific package of king trumpet mushrooms has been UV-treated depends on the grower and is usually stated on the label.
Ergothioneine Content
Ergothioneine is an amino acid with antioxidant properties that the human body cannot make on its own; it must come from food, and mushrooms are one of the richest known dietary sources. A laboratory analysis that measured ergothioneine across several cultivated mushroom types found levels ranging from about 0.4 to 2.0 milligrams per gram of dry weight. In that analysis, common white button mushroom contained the least ergothioneine, while portabella (a mature brown variety of the same species) contained more. Every “specialty” mushroom tested, including king trumpet, shiitake, common oyster, and maitake, contained a significantly greater amount of ergothioneine than white button mushroom, and there was no statistically significant difference in ergothioneine content among those specialty mushrooms.
In plain terms: king trumpet is a good source of ergothioneine, roughly on par with shiitake, oyster, and maitake mushrooms, and higher than plain white button mushroom.
Beta-Glucan Content Compared to Other Mushrooms
Beta-glucans are polysaccharides in the mushroom’s cell wall that have been studied for effects on the immune system and cholesterol metabolism, mostly in laboratory and animal research. A 2021 laboratory analysis published in the journal Nutrients measured beta-glucan content across several commercially grown mushrooms, reported in grams per 100 grams of dry matter:
- King trumpet (Pleurotus eryngii): about 15.3 grams of beta-glucans (19.2 grams total glucans).
- Common oyster mushroom: about 24.2 grams of beta-glucans.
- Shiitake: about 20.0 to 25.3 grams of beta-glucans, depending on cap versus stalk.
- Chanterelle: about 24.0 to 27.0 grams of beta-glucans.
- White button mushroom: about 8.6 to 12.3 grams of beta-glucans, the lowest of the group tested.
By this measure, king trumpet has meaningfully more beta-glucan than white button mushroom, though somewhat less than common oyster mushroom or shiitake in this particular analysis. Beta-glucan content varies by growing conditions, mushroom part, and testing method, so treat these as general reference ranges rather than fixed values.
What Human Research Actually Shows
Human clinical research on king trumpet mushroom specifically is limited but growing. A small controlled study in adults with obesity found that a meal containing king trumpet mushroom providing about 4.5 grams of beta-glucans was linked to changes in the release of certain amino acids into the bloodstream during digestion, and the same research group has previously reported that a similar king trumpet meal was associated with improved post-meal blood sugar response and changes in the appetite-related hormone ghrelin. This research was conducted with small numbers of participants, so it should be read as an early but real human signal, not as evidence that eating king trumpet mushroom treats any condition.
Beyond this, most available evidence on Pleurotus species’ immune and metabolic effects comes from combined-mushroom formulas, other Pleurotus species like common oyster mushroom, or general mushroom-food-frequency studies rather than king trumpet on its own.
Preclinical and Laboratory Findings (Not Yet Confirmed in Humans)
Most of what is known about king trumpet’s individual compounds comes from cell-based (in vitro) or non-human research. These findings point to biologically plausible mechanisms but have not been confirmed as health benefits in human clinical trials:
- Mushroom beta-glucan extracts, including from Pleurotus species, have shown immune-signaling activity in human immune cells studied in the lab (in vitro), a different kind of evidence than a clinical trial in living people.
- Combined mushroom formulas that included Pleurotus species alongside reishi and maitake showed immune-modulating activity in laboratory macrophage models, but this tested a mixed formula, not king trumpet alone.
- Mineral and antioxidant content varies by growing substrate and strain in agricultural studies, meaning nutrient levels in one batch of king trumpet mushroom will not be identical to another.
Safety, Food-Handling Cautions, and Who Should Be Extra Careful
King trumpet mushroom is a widely eaten culinary food, and for most healthy adults eating it cooked as part of a meal carries the same general food-safety considerations as other fresh produce. A few points are worth extra attention:
- Listeria risk in processing environments: A published survey of king oyster mushroom production plants found Listeria monocytogenes present in a portion of both mushroom samples and plant environmental samples tested. This does not mean every package is contaminated, but it is a documented reason to cook mushrooms thoroughly rather than eat them raw, especially for people who are pregnant, are older adults, are very young, or have a weakened immune system, since these groups face higher risk of serious illness from listeriosis.
- Mushroom identification: Store-bought king trumpet mushroom is cultivated and identified by the grower. If you ever forage mushrooms in the wild, never eat one based on a resemblance to king trumpet or any edible species without confirmation from an experienced, qualified forager, since several toxic mushroom species can resemble edible ones.
- Allergies and sensitivities: As with any new food, introduce it in a small amount first if you have not eaten mushrooms before, and stop if you notice any allergic reaction.
- Selenium and mineral supplements: Mushrooms are a food source of selenium, and food sources are not associated with the toxicity risk of concentrated supplements. The NIH Office of Dietary Supplements sets the adult upper intake limit for selenium from all sources, including food and supplements, at 400 micrograms per day; this is relevant mainly for people also taking selenium supplements, not for people simply eating mushrooms as food.
- Medicines and health conditions: There is no well-documented major drug interaction specific to king trumpet mushroom as a food. If you take medication, are managing a health condition, or are pregnant or breastfeeding, ask a qualified clinician about how mushrooms or mushroom supplements fit your personal situation, particularly if you are considering a concentrated extract rather than the whole food.
Traditional and Modern Culinary Use
King trumpet has long been part of Mediterranean and Middle Eastern cooking in its wild-foraged form, and it has become a major cultivated crop across East Asia over the past few decades, with South Korea in particular producing it at large commercial scale. Its thick, dense stem holds up well to high-heat cooking methods like searing, roasting, and grilling, and its firm, slightly chewy texture is often compared to scallops or squid when sliced and pan-seared. The cap has a milder flavor than the stem and is sometimes used more like a traditional mushroom cap in sautés.
Quick Comparison Checklist
- Calories and fat: low, similar to other oyster mushrooms.
- Ergothioneine: comparable to shiitake, common oyster, and maitake; higher than white button mushroom.
- Beta-glucans: moderate to high compared to white button mushroom; somewhat lower than common oyster mushroom or shiitake in available lab analyses.
- Human clinical evidence: limited but present, mainly in the areas of post-meal blood sugar and protein digestion.
- Vitamin D2: low unless the mushroom or product has been deliberately UV-treated.
Frequently Asked Questions
Is king trumpet mushroom more nutritious than regular mushrooms?
It has a similar low-calorie, low-fat nutritional profile to other oyster mushrooms, with somewhat higher levels of several vitamins compared to common oyster mushroom in at least one comparative study. It is not dramatically different from other Pleurotus species in most respects, though its beta-glucan and ergothioneine content are both notably higher than plain white button mushroom.
Does king trumpet mushroom have proven health benefits?
A small human study found signals related to post-meal blood sugar, appetite hormones, and amino acid release when king trumpet mushroom was part of a meal, which is a preliminary but genuine finding. Most other proposed benefits come from laboratory or animal research on its compounds, not confirmed clinical trials on the whole mushroom in people, so they should be considered early-stage evidence rather than established facts.
Is king trumpet mushroom safe to eat raw?
Most culinary and food-safety guidance recommends cooking mushrooms rather than eating them raw, partly for texture and digestibility and partly because of documented contamination risks, including Listeria, found in some king oyster mushroom production environments. This is especially important for pregnant people, older adults, young children, and anyone with a weakened immune system.
Does king trumpet mushroom contain vitamin D?
Fresh king trumpet mushroom grown in a typical dark commercial growing room contains very little vitamin D2, similar to most fresh cultivated mushrooms. Some growers expose mushrooms to ultraviolet light after harvest specifically to raise vitamin D2 content; check the product label to see if this has been done.
The Bottom Line
King trumpet mushroom is a low-calorie, low-fat food that contains meaningful amounts of potassium, ergothioneine, and beta-glucans, placing it nutritionally in line with other well-studied Pleurotus species like common oyster mushroom. Human clinical research on this specific species is still limited to a small number of studies, mostly focused on post-meal blood sugar and digestion, while most claims about immune or antioxidant effects currently rest on laboratory and animal research rather than confirmed human outcomes. As with any mushroom, cook it thoroughly, introduce it gradually if it is new to your diet, and talk with a qualified clinician before using concentrated mushroom extracts if you are pregnant, immunocompromised, or managing a health condition.
This article is for general educational purposes and is not medical advice. It does not diagnose, treat, or prevent any disease, and it is not a recommendation to use any supplement. Evidence strength differs by study type, and preclinical or animal findings do not guarantee the same effect in humans. See our evidence grading and source policy for how we classify research on this site, and our medical disclaimer for the full scope of what this content does and does not cover. Ask a qualified clinician about personal risks, medicines, pregnancy, or symptoms before making dietary changes.