Nameko, a slippery cooking mushroom that grows in clusters.

Mushrooms · Culinary mushroom

Nameko

Pholiota microspora (also written Pholiota nameko) · also called Butterscotch mushroom, slippery mushroom

Nameko is a small amber-brown Japanese mushroom with a slippery coating, used in miso soup and hot pots. As a food it is low in energy, with some fibre, potassium and B vitamins. Health research is thin: we found no human trial, only lab and mouse work on extracts. The one documented risk is a lung allergy in people who breathe the spores while growing it.

General information, not medical advice. Last substantive update October 25, 2026 · Not medically reviewed. A named clinician has not signed off on this page. How this page is made

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About Nameko

Nameko is a slippery cooking mushroom from Japan. As a food it is low in energy and has some fibre, potassium and B vitamins. We found no human trial of any health benefit; the research is lab and mouse work on purified extracts. The documented risk is a lung allergy in growers who breathe the spores. Metal levels depend on where the mushroom was grown.

What it is

Nameko is a mushroom of the genus Pholiota, in the fungus family Strophariaceae. It is not a plant. GBIF, a public biodiversity database, lists both Pholiota microspora and Pholiota nameko as accepted species, so a label may use either name. Japanese sources use P. microspora.

Almost all Japanese commercial nameko is grown on sawdust, and a genetic study concluded the cultivated strains come from a single wild strain collected in Fukushima. The slippery coating is a gel: studies describe a beta-glucan in extracts and a mucilage that one paper calls mainly pectin.

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How it is used

It is used as a cooking mushroom in miso soup and hot pots, and sold fresh, jarred, dried and as home-growing kits. We read no source describing traditional medicinal use. A factory study (summary-only) found that pre-cooking in hot water moves much of the protein, amino acids and phenolics into the liquid, which is why the broth carries flavour.

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What the research shows

No randomised or controlled human trial of nameko as a food or supplement was found in PubMed. Reviews of nameko polysaccharide describe lab and animal work, and one says clinical trial reports are scarce.

The animal and lab studies used purified fractions: a polysaccharide that lowered immune-cell signalling in mouse cells, a beta-glucan that reduced pain behaviour in mice, a zinc-enriched mycelium extract that improved blood fats in mice, a protein that slowed implanted tumour cells in mice, and extracts with mixed antioxidant results in test tubes. None of this shows that eating nameko helps anyone.

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Fruiting body, mycelium and extracts are different

The cooked cap and stem are the usual food. Several animal studies used mycelium grown in liquid culture, sometimes zinc-enriched, or purified fractions. Their results do not carry over to the cooked mushroom. We found no finished nameko supplement with human evidence and no quality data for such products.

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Rules and official statements

We did not find or read a regulator statement about nameko, so none is quoted here. Nameko is sold as a food. Ask a doctor or pharmacist before using concentrated extracts, especially if you take regular medicines.

At a glance

Traditional uses history, not proof

No traditional medicinal use of nameko was described in the sources we read.
It is a cooking mushroom: nearly all Japanese commercial nameko is grown on sawdust (99% of production in one report).

Studied for research

Nutrition as a food: values measured, no health effect shown, insufficient
Immune-cell signalling, lab only, insufficient
Pain and inflammation, one mouse study, insufficient
Antioxidant tests, test tube only and mixed, insufficient
Blood fats and liver, mouse study of a special extract, insufficient
Tiredness, mouse swim test, insufficient
Cancer cells, purified protein in mice, insufficient

Main compounds

Beta-glucan, a fibre-like carbohydrate that makes the coating gel
Pectin-rich mucilage on the cap
Ergothioneine and trehalose, measured in the food

Common forms

Fresh or jarred, cooked
Dried
Home-growing kits
Polysaccharide or protein extracts made in laboratories

Research links: Chest 1989: lung allergy from nameko spores (abstract) · Internal Medicine 1996: farmer case (abstract) · Beijing survey of metals in edible fungi (abstract) · Canned mushrooms in Spain: metals (abstract) · Nameko polysaccharide review, 2025 (abstract) · Research Library · Genes & Biomarkers Library

What it is and its history

Accepted scientific name: Pholiota microspora (also written Pholiota nameko; both are listed as accepted in GBIF)
Naming authority: (Berkeley) Saccardo for P. microspora; (T.Itô) S.Ito & S.Imai for P. nameko (GBIF)
Synonyms: Pholiota nameko (T.Itô) S.Ito & S.Imai (listed as a separate accepted species in GBIF, not a synonym there); Kuehneromyces nameko and Collybia nameko (older names from our earlier record; not re-checked)
Common names: Nameko (Japanese); Butterscotch mushroom (English); Slippery mushroom (English)
Family or group: Strophariaceae (a fungus family), not a plant
Classification: Fungi > Basidiomycota > Agaricomycetes > Agaricales > Strophariaceae > Pholiota > Pholiota microspora
Native range: Japan is where the cultivated strains come from (Hirao 2022). Wild range not checked.
Habitat: Not checked in the sources read. Earlier record: a cold-triggered mushroom that fruits in autumn; not re-checked.
What it looks like: Fruiting body: Earlier record (Wikipedia, not re-checked): a small amber-brown cap with a slippery coating. The cap mucilage is described as mainly pectin by Moriwaki 2026.
Cultivation: Sawdust cultivation accounts for 99% of Japanese production, and all current Japanese commercial strains appear to descend from a single wild strain collected in Fukushima (Hirao 2022). Sold fresh, jarred, dried and as home-growing kits in some places.
Harvest and processing: A 2026 factory study (summary-only) describes pre-cooking in hot water, which moves protein, amino acids and phenolics into the liquid.
Look-alikes and adulterants: Name: Other wild Pholiota and gilled mushrooms; Note: No source we read lists look-alikes for wild nameko. Do not identify wild mushrooms from this page.
Sustainability and conservation: Not checked.

Traditional use and history history, not clinical proof

Tradition or era	Documented use	Source
Modern Japanese cultivation	Nameko is one of the most common edible mushrooms in Japan, grown on sawdust. A genetic study concluded that cultivated strains arose from one domestication event from a wild strain collected in Fukushima.	p37089630
Traditional medicine	No traditional medicinal use of nameko was described in any source we read. It is a culinary mushroom.	p37089630

Traditional use shows how it was used. It does not show that it works or is safe today.

What is inside, and how it may work

What it contains and how those compounds act in cells and animals. Laboratory and animal mechanisms are not proven effects in people.

Main compounds

Compound	Family	Where it is concentrated	Activity studied	Level of evidence
Beta-glucan with (1-3) links and side chains	polysaccharide	Fruiting body (hot-water or cold-water extract) 1.2 g per 100 g fresh raw nameko (SD 0.4, n = 3) in the NARO survey (summary-only). Hot-water extract yield 1.46% in one study.	Gels in water and thickens soups. Reduced pain behaviour in mice as a purified fraction. ^{16 1 11}	Animal research
Mucilage, reported as mainly pectin	polysaccharide	Slimy surface layer	Formed a gel with Fe(III) that clumped microplastics in the lab. This is an environmental finding, not a health one. ¹⁰	Laboratory research
Mixed polysaccharides (glucose, mannose, galactose)	polysaccharide	Fruiting body extracts A cold-water extract was mannose 24.1%, galactose 44.9%, glucose 31%.	Described in the lab; the 2025 review adds xylose and arabinose and lists antioxidant, blood-fat-lowering and immune-regulating activity. ^{16 21}	Review
Zinc-enriched mycelium polysaccharide (MZPS)	polysaccharide	Mycelium grown in culture, not fruiting body Zinc 16.68 +/- 0.73 mg/g; weight-average molecular weight 3.64 x 10^4 Da; glucose, mannose, galactose, arabinose.	Improved blood and liver fats in mice on a high-fat diet. ²⁰	Animal research
Ergothioneine	amino acid derivative	Fruiting body 0.82 mg per g dry weight (SD 0.03; one producer, one batch; summary-only).	Measured only; no effect tested. ⁸	Theory
Trehalose	sugar	Fruiting body 0.77 g per 100 g fresh (SD 0.13, n = 3; summary-only).	Measured only. ¹¹	Theory
Antitumour protein PNAP	protein	Purified from the mushroom	Slowed implanted human breast-cancer cells in mice. ¹⁸	Animal research

Mechanisms, receptors and pathways

Target or pathway	Gene or receptor	What was found	Level
TLR2 and NF-kB signalling in dendritic cells	TLR2; NFKB1, NFKB2, RELA, MYD88, TRAF6	A purified polysaccharide lowered NF-kB pathway genes and proteins and two maturation markers in mouse cells, and the effect weakened when TLR2 was blocked with an antibody. ⁷	Laboratory research
Death-receptor and mitochondrial cell-death pathways	not specified in the abstract	A purified protein switched on these pathways in implanted human tumour cells in mice and shifted the Th1/Th2 balance towards Th1. ¹⁸	Animal research
Blood-fat and liver oxidative stress markers	not specified	A zinc-enriched mycelium polysaccharide improved blood and liver fats and antioxidant markers (SOD, T-AOC, MDA, LPO) in mice. ²⁰	Animal research
Alpha-glucosidase enzyme and probiotic growth	alpha-glucosidase	Some extracts blocked the enzyme by 30 to 50% in test tubes and raised growth of two probiotic strains in cultures. ¹³	Laboratory research

Absorption, metabolism and elimination

Absorption: Not found in the sources read.
Distribution: Not found.
Metabolism: Not found.
Elimination: Not found.
Bioavailability: Not established.

Isolated compounds versus whole extracts

Nearly all health-style research uses purified polysaccharides, one purified protein, or zinc-enriched mycelium extracts. These are not the same as eating the cooked fruiting body, and none has human trial evidence.

Nutritional composition

Raw nameko is low in energy. The Japanese food table (summary-only) lists 21 kcal, 3.4 g fibre, 240 mg potassium, 5.3 mg niacin and 60 micrograms folate per 100 g, and 0 vitamin D (no UV-exposed value found). These describe the food; they do not show a health effect.

9benefits and uses looked at

23studies and sources checked

Not enough evidencebest evidence rating found

7lab markers tracked in trials

9 not enough evidence

What was looked at

The 9 benefits and uses checked for Nameko, each with how strong the evidence is. Tap one to open it.

Immune-cell signalling (lab only)Not enough evidence
Inflammation and pain (mouse only)Not enough evidence
Antioxidant activity (test tube only)Not enough evidence
Nameko as a food (what is in it)Not enough evidence
Blood fats and liver (mouse, mycelium extract)Not enough evidence
Stamina and tiredness (mouse swim test)Not enough evidence
Cancer cells (purified protein in mice)Not enough evidence
Gut bacteria and a sugar-digesting enzyme (test tube)Not enough evidence
Serum cytokines in healthy volunteers (unclear how tested)Not enough evidence

Lab markers tracked in the studies

CD40 and CD80 maturation markers (mouse cells)Pain behaviour in the mouse formalin testRadical scavenging (ABTS and OH tests)Blood and liver fats (mouse)Forced swim time (mouse)39 serum cytokines (route unclear)Alpha-glucosidase blocking (test tube)

What is Nameko good for?

The uses people ask about and how strong the evidence is for each. Everything here is lab, mouse or food-table information, and none is proven in people. Read this together with the Safety tab.

Benefits, one by one

Each card is a research question, not a promise. Tap a goal to filter. Open a card to see the studies, doses and limits.

Immune-cell signalling (lab only)

Not enough evidence

In the lab, a purified nameko polysaccharide changed signalling in mouse immune cells. No person has been tested. This is a research lead, not a health effect.

3 studiesA purified polysaccharide fraction. Not the cooked mushroom and not a…

Studies, doses and limits

Results

In mouse dendritic cells, CD40 and CD80 maturation markers fell and NF-kB pathway genes and proteins were lower (abstract gives no figures).

Effect sizes as reported

Lower signalling in mouse cells in dishes

Why this rating

Only cells in dishes. Reviews say clinical trials are scarce. Lab immune effects often do not carry over to people.

Form and dose studied

A purified polysaccharide fraction. Not the cooked mushroom and not a finished supplement. No amounts are given on this page.

Who was studied

Mouse bone marrow-derived dendritic cells

Limits

One cell study; purified fraction; no animals or people; the same research group wrote other nameko papers listed here.

Why researchers looked

Mushroom polysaccharides are often studied for immune effects, so researchers tested nameko fractions on immune cells.

Traditional use

No traditional medicinal use of nameko was described in the sources we read. It is a cooking mushroom.

Proposed mechanism Laboratory research

A purified polysaccharide (PNPS-1) lowered NF-kB signalling and two maturation markers in mouse dendritic cells. The authors link this to the TLR2 receptor. This is cell work only.

A proposed mechanism does not show that the effect happens in people.

No harm from eating nameko was described in the sources we read. The documented risks are lung allergy from breathing spores in growing rooms and metals taken up from the growing medium. See the Safety tab.

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Inflammation and pain (mouse only)

Not enough evidence

A purified beta-glucan from nameko reduced pain behaviour in mice after an injected irritant. This was one animal study and says nothing about people eating nameko.

2 studiesA purified beta-glucan made by hot-water extraction. Not food. No amo…

Studies, doses and limits

Results

Pain behaviour fell by 24.8%, 56.9% and 82.3% at 0.3, 1.0 and 3.0 mg per kg in mice in the formalin test.

Effect sizes as reported

Large drops in mouse pain behaviour at the tested levels

Why this rating

One animal study of a purified fraction with no human follow-up.

Form and dose studied

A purified beta-glucan made by hot-water extraction. Not food. No amounts are advised here.

Who was studied

Mice

Limits

One study; mouse model of pain; purified fraction; not repeated in the sources we read.

Why researchers looked

Beta-glucans from mushrooms are studied for anti-inflammatory activity, and this one also gelled well in water.

Traditional use

No traditional medicinal use of nameko was described in the sources we read. It is a cooking mushroom.

Proposed mechanism Animal research

The mechanism was not studied in the abstract. The glucan is a (1-3)-linked beta-glucan with side chains, which also makes it thicken water.

A proposed mechanism does not show that the effect happens in people.

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Antioxidant activity (test tube only)

Not enough evidence

Some nameko extracts mopped up free radicals in test tubes, but one study found no strong antioxidant activity. Results are mixed and none is from people.

3 studiesEnzyme-made and ultrasound extracts. Not food.

Studies, doses and limits

Results

No strong antioxidant activity was observed, although extracts were able to scavenge ABTS and OH radicals (abstract).

Effect sizes as reported

Mixed: weak overall in one study, some activity in tests

Why this rating

Lab radical tests only. The 2026 review (summary-only) also lists antioxidant activity from preclinical work.

Form and dose studied

Enzyme-made and ultrasound extracts. Not food.

Who was studied

Test tubes

Limits

Different extracts and tests give different answers; nothing in animals or people was read.

Why researchers looked

Antioxidant tests are cheap and common, so many mushroom extracts get tested this way.

Traditional use

No traditional medicinal use of nameko was described in the sources we read. It is a cooking mushroom.

Proposed mechanism Laboratory research

Test-tube radical scavenging (ABTS and OH). Test-tube scores do not show what happens in the body.

A proposed mechanism does not show that the effect happens in people.

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Nameko as a food (what is in it)

Not enough evidence

Fresh nameko is a low-energy food. Japan's national food table lists about 21 kcal per 100 g, with some fibre, potassium and B vitamins. These are measured amounts in the food. They do not show a health effect from eating it.

3 studiesRaw or cooked whole mushroom, fresh, jarred or dried. No supplement a…

Studies, doses and limits

What the trials found

No trial tested a health outcome from eating nameko. The values come from a national food table and analytical studies.

Results

Per 100 g raw (MEXT, summary-only): 21 kcal, 3.4 g fibre, 240 mg potassium, 5.3 mg niacin, 60 micrograms folate, 0 vitamin D. NARO: beta-glucan 1.2 g and trehalose 0.77 g per 100 g (n = 3). One Chinese sample, per gram dry weight: ergothioneine 0.82 mg.

Effect sizes as reported

Composition is documented; health benefit is not shown

Why this rating

A measured amount in food is not proof of benefit. Each figure is one table row or one batch.

Form and dose studied

Raw or cooked whole mushroom, fresh, jarred or dried. No supplement amounts are given or advised.

Who was studied

General food-eating adults; no specific group studied

Limits

Values vary by strain, growing medium, harvest, drying and cooking. Dry-weight and fresh-weight numbers must not be mixed. All three sources were summary-only this round.

Why researchers looked

People ask what is in a mushroom they eat in soup, so food tables and a few analytical papers measure it.

Traditional use

No traditional medicinal use of nameko was described in the sources we read. It is a cooking mushroom.

Proposed mechanism Authoritative guidance

Not a mechanism question. The slippery coating is a polysaccharide gel, which is why nameko thickens soups. A 2026 factory study found that much of the protein, free amino acids and phenolics move into the hot water during pre-cooking (summary-only).

A proposed mechanism does not show that the effect happens in people.

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Blood fats and liver (mouse, mycelium extract)

Not enough evidence

A zinc-enriched polysaccharide made from nameko mycelium improved blood fat and liver measures in mice fed a high-fat diet. It is a special lab product, not the cooked mushroom.

2 studiesMycelium grown in culture, zinc-enriched polysaccharide. Not fruiting…

Studies, doses and limits

Results

In mice on a high-fat diet, total cholesterol, triglycerides, HDL-C, LDL-C and VLDL-C and liver fats were improved, with less liver injury on pathology (abstract gives no figures).

Effect sizes as reported

Better fat and liver measures in mice

Why this rating

One mouse study of a zinc-enriched mycelium extract.

Form and dose studied

Mycelium grown in culture, zinc-enriched polysaccharide. Not fruiting body, not food.

Who was studied

Mice

Limits

One study; special extract; model of fatty liver; no people.

Why researchers looked

Mushroom polysaccharides are tested for fat-lowering effects in mice.

Traditional use

No traditional medicinal use of nameko was described in the sources we read. It is a cooking mushroom.

Proposed mechanism Animal research

Not described beyond improved fat and antioxidant markers (SOD, T-AOC, MDA, LPO) in the mice.

A proposed mechanism does not show that the effect happens in people.

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Stamina and tiredness (mouse swim test)

Not enough evidence

A nameko polysaccharide lengthened forced-swim time in mice. That is a mouse test and does not say whether nameko helps tired people.

1 studiesA purified polysaccharide. Not food.

Studies, doses and limits

Results

Forced swim time rose from 121.58 and 101.91 min to 154.95 and 134.13 min in male and female mice.

Effect sizes as reported

About 32 to 33 minutes longer in mice (calculated from the abstract figures)

Why this rating

One mouse study with no human follow-up.

Form and dose studied

A purified polysaccharide. Not food.

Who was studied

Male and female mice

Limits

One study; animal test; purified fraction.

Why researchers looked

Swim-to-exhaustion tests in mice are a common first screen for anti-fatigue claims.

Traditional use

No traditional medicinal use of nameko was described in the sources we read. It is a cooking mushroom.

Proposed mechanism Animal research

The authors also report higher SOD and lower MDA after the polysaccharide, which they link to less oxidative stress.

A proposed mechanism does not show that the effect happens in people.

¹⁹

Cancer cells (purified protein in mice)

Not enough evidence

A purified protein from nameko slowed implanted human breast-cancer cells growing in mice. This is a lab finding about one protein. It is not a treatment and says nothing about eating nameko.

1 studiesA purified protein (PNAP). Not food and not a supplement.

Studies, doses and limits

Results

Inhibited growth of MCF-7 tumour implants in mice (abstract gives no figures).

Effect sizes as reported

Slower implanted-tumour growth in mice

Why this rating

One mouse study of a purified protein with implanted human cells.

Form and dose studied

A purified protein (PNAP). Not food and not a supplement.

Who was studied

Mice carrying human breast-cancer cell implants

Limits

Single study; no people; not a treatment.

Why researchers looked

Researchers look for proteins in edible fungi that kill cancer cells in the lab.

Traditional use

No traditional medicinal use of nameko was described in the sources we read. It is a cooking mushroom.

Proposed mechanism Animal research

The authors report that the protein switched on cell-death pathways in the tumour cells and shifted the immune balance towards Th1.

A proposed mechanism does not show that the effect happens in people.

¹⁸

Gut bacteria and a sugar-digesting enzyme (test tube)

Not enough evidence

In test tubes, some nameko extracts helped two probiotic bacteria grow and blocked an enzyme that digests starch. It was not tested in animals or people.

1 studiesEnzyme-made and ultrasound extracts. Not food.

Studies, doses and limits

Results

All extracts showed possible prebiotic activity (some raising Lactobacillus acidophilus La-5 and Bifidobacterium animalis BB12 growth by 1.4 to 2 log cycles); ultrasound, Flavourzyme and Cellulase extracts blocked alpha-glucosidase by 30 to 50%.

Effect sizes as reported

Lab growth and enzyme-blocking effects

Why this rating

Test tubes and bacterial cultures only.

Form and dose studied

Enzyme-made and ultrasound extracts. Not food.

Who was studied

Test tubes

Limits

One lab study; not tested in animals or people.

Why researchers looked

Fibre-like mushroom carbohydrates may feed gut bacteria, and enzyme blockers are screened for blood-sugar effects.

Traditional use

No traditional medicinal use of nameko was described in the sources we read. It is a cooking mushroom.

Proposed mechanism Laboratory research

Prebiotic growth in bacterial cultures and alpha-glucosidase blocking in test tubes.

A proposed mechanism does not show that the effect happens in people.

¹³

Serum cytokines in healthy volunteers (unclear how tested)

Not enough evidence

One 2012 paper measured 39 cytokines in the serum of healthy volunteers and called a nameko polysaccharide anti-inflammatory. The abstract does not say whether volunteers took it, so this is not good evidence of an effect from eating nameko.

1 studiesPurified polysaccharide PNPS-1. Not food.

Studies, doses and limits

What the trials found

Not clear. The abstract does not say whether volunteers swallowed the polysaccharide or whether it was tested on their serum in the lab.

Results

Reported as significant anti-inflammatory activity, no figures in the abstract.

Effect sizes as reported

Reported anti-inflammatory signal, unclear design

Why this rating

Design not described in the abstract; no controls or sizes are given there.

Form and dose studied

Purified polysaccharide PNPS-1. Not food.

Who was studied

Healthy volunteers' serum

Limits

Abstract only; route of exposure unknown; one paper.

Why researchers looked

It is the only paper we found that mentions human samples.

Traditional use

No traditional medicinal use of nameko was described in the sources we read. It is a cooking mushroom.

Proposed mechanism Laboratory research

A cytokine network map was drawn from the measurements. No firm mechanism.

A proposed mechanism does not show that the effect happens in people.

⁶

Connections to the rest of health

How Nameko connects to the rest of our health knowledge graph. Every link says what kind of connection it is. A safety link (for example to the liver) is a warning, not a benefit. A study that merely mentions a topic never creates a benefit link.

Explore every connection: goals, body systems, organs, symptoms, genes

Kind of connection Connected to Search

A. Wellness goals

Connected to	Kind of connection	Evidence status	Context	Studies
Immune Support	Preliminary mechanism	Not enough evidence	Immune-cell signalling (lab only): In the lab, a purified nameko polysaccharide changed signalling in mouse immune cells. No person has been tested. This is a research lead, not a health effect. Cancer cells (purified protein in mice): A purified protein from nameko slowed implanted human breast-cancer cells growing in mice. This is a lab finding about one protein. It is not a treatment and says nothing about eating nameko.	^{7 21 17 18}
Inflammation Balance	Preliminary mechanism	Not enough evidence	Inflammation and pain (mouse only): A purified beta-glucan from nameko reduced pain behaviour in mice after an injected irritant. This was one animal study and says nothing about people eating nameko.	^{1 17}
Healthy Aging	Preliminary mechanism	Not enough evidence	Antioxidant activity (test tube only): Some nameko extracts mopped up free radicals in test tubes, but one study found no strong antioxidant activity. Results are mixed and none is from people.	^{13 21 17}
Balanced Nutrition	Biological association	Not enough evidence	Nameko as a food (what is in it): Fresh nameko is a low-energy food. Japan's national food table lists about 21 kcal per 100 g, with some fibre, potassium and B vitamins. These are measured amounts in the food. They do not show a health effect from eating it.	^{9 11 8}
Cholesterol Balance	Preliminary mechanism	Not enough evidence	Blood fats and liver (mouse, mycelium extract): A zinc-enriched polysaccharide made from nameko mycelium improved blood fat and liver measures in mice fed a high-fat diet. It is a special lab product, not the cooked mushroom.	^{20 21}
Reduce Fatigue	Preliminary mechanism	Not enough evidence	Stamina and tiredness (mouse swim test): A nameko polysaccharide lengthened forced-swim time in mice. That is a mouse test and does not say whether nameko helps tired people.	¹⁹
Blood Sugar Balance	Preliminary mechanism	Not enough evidence	Gut bacteria and a sugar-digesting enzyme (test tube): In test tubes, some nameko extracts helped two probiotic bacteria grow and blocked an enzyme that digests starch. It was not tested in animals or people.	¹³
Inflammation Balance		Not enough evidence	Serum cytokines in healthy volunteers (unclear how tested): One 2012 paper measured 39 cytokines in the serum of healthy volunteers and called a nameko polysaccharide anti-inflammatory. The abstract does not say whether volunteers took it, so this is not good evidence of an effect from eating nameko.	⁶

B. Body systems

Connected to	Kind of connection	Evidence status	Context	Studies
Immune System	Biological association	Not enough evidence	Studied for: Immune-cell signalling (lab only) Studied for: Inflammation and pain (mouse only)	^{7 21 17 1 13 18 6}
Nervous System	Biological association	Not enough evidence	Studied for: Inflammation and pain (mouse only)	^{1 17}
Digestive System	Biological association	Not enough evidence	Studied for: Nameko as a food (what is in it) Studied for: Gut bacteria and a sugar-digesting enzyme (test tube)	^{9 11 8 13}
Cardiovascular System	Biological association	Not enough evidence	Studied for: Blood fats and liver (mouse, mycelium extract)	^{20 21}
Hepatic System	Biological association	Not enough evidence	Studied for: Blood fats and liver (mouse, mycelium extract)	^{20 21}
Musculoskeletal System	Biological association	Not enough evidence	Studied for: Stamina and tiredness (mouse swim test)	¹⁹

C. Body parts and organs

Connected to	Kind of connection	Evidence status	Context	Studies
Lungs	Adverse effect or risk	Low certainty	Three case reports of hypersensitivity pneumonitis in growers. Preparation or compound: Spores breathed in growing rooms; not eating	^{12 5 4}

E. Health conditions

Connected to	Kind of connection	Evidence status	Context	Studies
Extrinsic allergic alveolitis	Adverse effect or risk	Low certainty	Mushroom-worker lung allergy. Preparation or compound: Nameko spores	^{12 5 4}

G. Root causes and contributing factors

Connected to	Kind of connection	Evidence status	Context	Studies
Heavy metal exposure	Biological association	Low certainty	Low in two surveys; aluminium near the limit in one model of canned nameko. Preparation or compound: Fruiting body, depends on growing medium	^{3 2 14}

I. Biomarkers

Connected to	Kind of connection	Evidence status	Context	Studies
CD40 and CD80 maturation markers (mouse cells)	Biological association	Not enough evidence	Measured in trials: lowered. A lab change is not the same as a health benefit.	⁷
Pain behaviour in the mouse formalin test	Biological association	Not enough evidence	Measured in trials: lowered. A lab change is not the same as a health benefit.	¹
Radical scavenging (ABTS and OH tests)	Biological association	Not enough evidence	Measured in trials: mixed. A lab change is not the same as a health benefit.	¹³
Blood and liver fats (mouse)	Biological association	Not enough evidence	Measured in trials: mixed. A lab change is not the same as a health benefit.	²⁰
Forced swim time (mouse)	Biological association	Not enough evidence	Measured in trials: raised. A lab change is not the same as a health benefit.	¹⁹
39 serum cytokines (route unclear)	Biological association	Not enough evidence	Measured in trials: mixed. A lab change is not the same as a health benefit.	⁶
Alpha-glucosidase blocking (test tube)	Biological association	Not enough evidence	Measured in trials: lowered. A lab change is not the same as a health benefit.	¹³

J. Genes, receptors and enzymes

Connected to	Kind of connection	Evidence status	Context	Studies
Toll-like receptor 2 (TLR2)	Preliminary mechanism	In vitro	A purified nameko polysaccharide appeared to act through TLR2 in mouse cells.	⁷
Alpha-glucosidase	Preliminary mechanism	In vitro	Blocked 30 to 50% by some extracts in test tubes.	¹³

K. Biological pathways

Connected to	Kind of connection	Evidence status	Context	Studies
NF-kB signalling	Preliminary mechanism	In vitro	Lowered by the same polysaccharide in mouse cells.	⁷

L. Active compounds

Connected to	Kind of connection	Evidence status	Context	Studies
Beta-glucan with (1-3) links and side chains	Biological association	Animal	Gels in water and thickens soups. Reduced pain behaviour in mice as a purified fraction. Preparation or compound: Fruiting body (hot-water or cold-water extract)	^{16 1 11}
Mucilage, reported as mainly pectin	Biological association	In vitro	Formed a gel with Fe(III) that clumped microplastics in the lab. This is an environmental finding, not a health one. Preparation or compound: Slimy surface layer	¹⁰
Mixed polysaccharides (glucose, mannose, galactose)	Biological association	Review	Described in the lab; the 2025 review adds xylose and arabinose and lists antioxidant, blood-fat-lowering and immune-regulating activity. Preparation or compound: Fruiting body extracts	^{16 21}
Zinc-enriched mycelium polysaccharide (MZPS)	Biological association	Animal	Improved blood and liver fats in mice on a high-fat diet. Preparation or compound: Mycelium grown in culture, not fruiting body	²⁰
Ergothioneine	Biological association	Theory	Measured only; no effect tested. Preparation or compound: Fruiting body	⁸
Trehalose	Biological association	Theory	Measured only. Preparation or compound: Fruiting body	¹¹
Antitumour protein PNAP	Biological association	Animal	Slowed implanted human breast-cancer cells in mice. Preparation or compound: Purified from the mushroom	¹⁸

Each connection is stored with the ingredient, the connected record, the kind of connection, the evidence status, the supporting studies, the preparation or compound involved, and a review date (last reviewed October 25, 2026).

Evidence at a glance: what changed in 7 lab markers

Tap a number to show only those markers. Counts are markers, not people.

Other313

The evidence

The research centre for Nameko. Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.

Evidence by outcome

Bars show how many studies we found for each outcome, not how well it works. People are added up across trials only (reviews are not added, to avoid double counting).

How we rate evidence

High certainty

Several well-run trials or reviews agree; further research is unlikely to change the picture much.

Moderate certainty

Good trials point the same way, but some doubt remains.

Low certainty

Small, short or inconsistent trials. The finding could change with better research.

Very low certainty

Very little or very weak human data. Treat as a possibility only.

Mixed findings

Trials or reviews disagree with each other.

Not enough evidence

Not enough human research to say either way.

Evidence against

Good research found no benefit, or found harm.

We take the reviewers' own risk-of-bias and GRADE statements where they exist, and otherwise judge from study size, design, consistency, directness and whether a product matches what is sold. Many publications do not make evidence high. Method note: We read PubMed records and abstracts for 14 papers (three case reports, three food or metal surveys, seven laboratory, animal or chemistry papers and one review), and checked the species names in GBIF. Two more records (the 2023 Japanese food table and a 2026 Scientific Reports analysis) and one 2026 RSC Advances review were carried over from an earlier read and are marked summary-only. No regulator page for nameko was found. Numbers come from abstracts. Certainty ratings are the compiler's own reading.

Study library: every study we checked 23

Design Research type Year from Search

Study	Design	People	Product, dose, length	Result
Abreu 2019 Gelling functional property, anti-inflammatory and antinociceptive bioactivities of beta-D-glucan from the edible mushroom Pholiota nameko. International Journal of Biological Macromolecules · PMID 30218731 · DOI	Animal research animal	Mice in the formalin-induced pain test	Purified beta-D-glucan (GHW-PN) made by hot-water extraction (1.46% yield) edible mushroom (part not stated in the abstract) Not shown here	The glucan thickened and gelled in water and kept its structure under simulated pasteurisation. At 0.3, 1.0 and 3.0 mg per kg it reduced inflammatory pain behaviour in mice by 24.8%, 56.9% and 82.3%. Less pain behaviour in mice after an injected irritant Methods, limits and funding Outcomes: Thickening behaviour of the glucan; pain response in mice Limitations: One mouse study of a purified fraction. It does not show an effect of eating nameko, and nothing was tested in people. Funding and conflicts: Not stated in the abstract Read: abstract
Chen 2024 Levels and health risk assessment of inorganic arsenic, methylmercury, and heavy metals in edible mushrooms collected from an online supermarket in China. Biological Trace Element Research · PMID 37526876 · DOI	Survey survey	Seven edible mushroom types bought from an online supermarket in China, 2015 to 2017	Edible mushrooms including Pholiota nameko fruiting body Not shown here	Chromium, cadmium and lead contamination were common across the mushrooms. The target hazard quotients for the five metals from P. nameko, A. auricula, A. aegirit and L. edodes were below 1. Hazard indices for A. blazei, T. matsutake and B. edulis were above 1. The ordering for cancer risk from inorganic arsenic ranked P. nameko third of seven, and all values were below the level the authors call a carcinogenic risk. Nameko hazard quotients below 1 in this survey Methods, limits and funding Outcomes: Chromium, arsenic, cadmium, mercury, methylmercury and lead; hazard quotients Limitations: Model-based risk estimate from market samples; the abstract gives no nameko-only figures. Funding and conflicts: Not stated in the abstract Read: abstract
Huang 2015 Market survey and risk assessment for trace metals in edible fungi and the substrate role in accumulation of heavy metals. Journal of Food Science · PMID 26077507 · DOI	Survey survey	285 285 samples of 9 edible fungi from Beijing markets, plus 7 cultivation bases	Edible fungi including Pholiota nameko fruiting body Not shown here	Metals in mushrooms rose and fell with metals in their growing medium (for Cd, Pb and As). Levels were relatively high in Lentinus edodes and relatively low in Tremella fuciformis and Pholiota nameko. Estimated weekly intake was lower than the WHO/FAO tolerable weekly intake. Nameko had relatively low metal levels in this survey Methods, limits and funding Outcomes: Cadmium, arsenic, mercury, lead, iron and zinc levels; weekly intake Limitations: Market samples in one city; the abstract gives no nameko-only figures. Funding and conflicts: Research support from a non-US government source per the PubMed record; no industry funding noted Read: abstract
Inage 1996 Hypersensitivity pneumonitis induced by spores of Pholiota nameko. Internal Medicine · PMID 8739786	Case report	1 A 42-year-old man who had been a mushroom farmer for 10 years	Inhaled Pholiota nameko spores spores in the work environment Not shown here	He had repeated bouts of dry cough, fever and breathlessness on effort. A precipitin test was positive for nameko spores and not for other antigens. After he was separated from the spores and given a corticosteroid, symptoms, inflammation and low blood oxygen quickly settled. Recovered after leaving the exposure and taking a corticosteroid Methods, limits and funding Outcomes: Symptoms, immune tests, oxygen level Limitations: One person; two changes happened together (leaving exposure and steroid), so each effect cannot be separated. Funding and conflicts: Not stated in the abstract Read: abstract
Ishii 1994 Hypersensitivity pneumonitis induced by inhalation of mushroom (Pholiota nameko) spores. Internal Medicine · PMID 7849381	Case report	1 A 49-year-old woman who had grown nameko indoors for three years	Inhaled Pholiota nameko spores spores from indoor cultivation Not shown here	Findings matched other forms of hypersensitivity pneumonitis. A blood test identified nameko spores as the cause. The authors say the indoor growing method appeared to play a major role. Hypersensitivity pneumonitis in an indoor grower Methods, limits and funding Outcomes: Lung biopsy, lavage fluid, immune tests Limitations: One person; the abstract does not describe the outcome. Funding and conflicts: Not stated in the abstract Read: abstract
Li 2012 Effects of the polysaccharide from Pholiota nameko on human cytokine network in serum. International Journal of Biological Macromolecules · PMID 22044749 · DOI	Laboratory research in-vitro	Healthy volunteers' serum (39 cytokines measured)	Pholiota nameko polysaccharide (PNPS-1) extract (part not stated in the abstract) Not shown here	The abstract says the polysaccharide showed significant anti-inflammatory activity and, from a cytokine network map, could affect innate and adaptive immunity and blood-cell formation. It does not say whether volunteers swallowed it or whether it was added to their serum in the lab, and it gives no figures. Reported as anti-inflammatory; unclear how it was tested Methods, limits and funding Outcomes: Levels of 39 cytokines in serum Limitations: The abstract does not say how the volunteers' serum was exposed. We treat it as laboratory evidence, not a human trial. Funding and conflicts: Research support from a non-US government source per the PubMed record; no industry funding noted Read: abstract
Li 2015 Effects of Pholiota nameko polysaccharide on NF-kB pathway of murine bone marrow-derived dendritic cells. International Journal of Biological Macromolecules · PMID 25812973 · DOI	Laboratory research in-vitro	Mouse bone marrow-derived dendritic cells grown in dishes	Purified Pholiota nameko polysaccharide (PNPS-1) extract of the mushroom (part not stated in the abstract) Not shown here	PNPS-1 decreased the maturation markers CD40 and CD80 on the cells, lowered mRNA of several NF-kB pathway genes and lowered IKK-beta and P65 protein. The effects were weaker when the cells were first treated with an anti-TLR2 antibody, which the authors read as direct interaction with the TLR2 receptor. Lower NF-kB signalling and lower maturation markers in mouse cells in dishes Methods, limits and funding Outcomes: Immune-cell maturation markers and NF-kB signalling genes and proteins Limitations: Cells in dishes, not animals or people. A purified fraction, not the cooked mushroom. Funding and conflicts: Research support from a non-US government source per the PubMed record; no industry funding noted Read: abstract
Meng 2026 Chemical composition, metabolomics, and functional potential of Pholiota nameko pre-cooking liquid Scientific Reports · Source · DOI	Product analysis n/a	3 Freeze-dried fruiting-body powder from one commercial processor in Yan'an, China (strain not named)	Pholiota nameko fruiting body powder and its pre-cooking liquid fruiting body Not shown here	Summary-only (read in full on 2026-10-23 for the earlier page, not re-opened): per gram dry weight, crude protein 205 mg, free amino acids 12.31 mg, ergothioneine 0.82 mg (SD 0.03) and total phenolics 0.27 mg (SD 0.02) from one producer and one batch. In 10 minutes in 95 C water, about 41% of the protein, 84% of the free amino acids and 63% of the phenolics moved into the water. Methods, limits and funding Outcomes: Protein, amino acids, ergothioneine, phenolics; what moves into the cooking water Limitations: One producer, one batch, a factory pre-cooking step rather than a home recipe. Dry-weight values are not comparable to fresh-weight values. Funding and conflicts: Academic paper (CC BY-NC-ND 4.0); funding not re-checked Read: summary-only
Ministry of Education 2023 Standard Tables of Food Composition in Japan 2023 (8th revised edition, supplement): nameko, cluster-harvested, raw (food no. 08020) Government food composition table · Source	Database record n/a	Raw nameko, per 100 g edible portion	Raw nameko (Pholiota microspora), cluster-harvested fruiting body Not shown here	Summary-only (read 2026-10-23 for the earlier page): about 92.1 g water, 21 kcal, 1.8 g protein, 0.2 g fat, 5.4 g carbohydrate, 3.4 g total dietary fibre, 240 mg potassium, 68 mg phosphorus, 0.5 mg zinc, 0.7 mg iron, 5.3 mg niacin, 60 micrograms folate and 0 vitamin D (no UV-exposed value found). Methods, limits and funding Outcomes: Energy and nutrient content per 100 g Limitations: One national table entry. Amounts vary by strain, medium, harvest and cooking. It describes what is in the food, not any health effect. Not re-opened on 2026-10-25. Funding and conflicts: Government source; independent Read: summary-only
Moriwaki 2026 Removal of microplastics or nanoplastics using nameko (Pholiota nameko) mucilage as a flocculant. Chemosphere · PMID 41903317 · DOI	Other n/a	Laboratory suspensions of plastic particles	Mucilage solution from nameko surface mucilage Not shown here	The authors describe nameko mucus as composed mainly of pectin. With Fe(III), the mucilage removed 95.3% of 1.0 micrometre polystyrene microplastics within 5 minutes, and 98.4% when nameko washing wastewater was used. Mucilage clumps plastic particles in the lab Methods, limits and funding Outcomes: Removal of microplastics from water Limitations: An environmental chemistry study, not a health study. Funding and conflicts: Not stated in the abstract Read: abstract
NARO (National Agriculture and Food Research Organization) Functional component content information, mushrooms (nameko, raw, n = 3) Government functional-component table · Source	Database record n/a	3 Raw nameko	Raw nameko fruiting body Not shown here	Summary-only: beta-glucan 1.2 g per 100 g fresh (SD 0.4) and trehalose 0.77 g per 100 g fresh (SD 0.13), mean of 3 analyses. Method and date not stated in the table. Methods, limits and funding Outcomes: Beta-glucan and trehalose content Limitations: Three analyses; method not stated; not re-opened on 2026-10-25. Funding and conflicts: Government source; independent Read: summary-only
Nakazawa 1989 Hypersensitivity pneumonitis due to mushroom (Pholiota nameko) spores. Chest · PMID 2707072	Case report	1 A 52-year-old mushroom worker	Inhaled Pholiota nameko spores spores in a mushroom-cultivating room Not shown here	Cough, breathlessness on effort and high fever began several hours after work in the cultivating room. Chest X-ray showed fine granular shadows in both lungs, and a lung biopsy showed granulomatous alveolitis. Antibodies and an immune-cell test reacted to the spore extract and not to other moulds. An inhalation test with the extract brought on similar symptoms. Hypersensitivity pneumonitis from nameko spores Methods, limits and funding Outcomes: Lung symptoms, scans, biopsy, immune tests Limitations: One person. A case report cannot show how often it happens. Exposure was in a workplace. Funding and conflicts: Not stated in the abstract Read: abstract
Rodrigues 2017 Chemical and structural characterization of Pholiota nameko extracts with biological properties. Food Chemistry · PMID 27596407 · DOI	Laboratory research in-vitro	Laboratory extracts (test tubes and bacterial cultures)	Enzyme-made and ultrasound extracts of Pholiota nameko mushroom (part not stated in the abstract) Not shown here	Cellulase and Viscozyme extractions gave the highest yields (67 to 77%). No strong antioxidant activity was observed, although the extracts did scavenge ABTS and OH radicals. Every extract showed possible prebiotic activity, some raising Lactobacillus acidophilus La-5 and Bifidobacterium animalis BB12 growth by 1.4 to 2 log cycles. Ultrasound, Flavourzyme and Cellulase extracts blocked alpha-glucosidase by 30 to 50%. Mixed: weak antioxidant result, some growth of two probiotic strains and some enzyme blocking, all in the lab Methods, limits and funding Outcomes: Extraction yield, antioxidant tests, prebiotic growth tests, alpha-glucosidase blocking, composition Limitations: Test-tube work on extracts. It does not show any effect in the body. Funding and conflicts: Not stated in the abstract Read: abstract
Rubio 2018 Trace element and toxic metal intake from the consumption of canned mushrooms marketed in Spain. Environmental Monitoring and Assessment · PMID 29564562 · DOI	Survey survey	100 100 canned mushroom samples grown in Spain	Canned mushrooms including Pholiota nameko fruiting body (canned) Not shown here	At an average intake of 300 g a day the authors say exposure to toxic metals does not pose a health risk. However, the contribution of lead (87.6%) in Lentinula edodes and aluminium (59.2%) in Pholiota nameko samples was near the maximum intake. Aluminium from nameko samples reached 59.2% of the intake limit in the authors' model Methods, limits and funding Outcomes: Fourteen metals including aluminium, cadmium and lead Limitations: Canned products in one country; a model assuming 300 g a day. Funding and conflicts: Not stated in the abstract Read: abstract
S Hirao 2022 Japanese "nameko" mushrooms (Pholiota microspora) produced via sawdust-based cultivation exhibit severe genetic bottleneck associated with a single founder. Mycoscience · PMID 37089630 · DOI	Other fungus	50 cultivars and 73 wild strains from across Japan	Pholiota microspora cultivars and wild strains fungal DNA Not shown here	Sawdust cultivation makes up 99% of Japanese production. Cultivated strains were much less genetically diverse than wild ones and clustered in one group, consistent with all commercial nameko descending from a single wild strain collected in Fukushima. Commercial nameko in Japan is genetically very uniform Methods, limits and funding Outcomes: Genetic diversity of cultivated versus wild strains Limitations: A genetic study of strains in Japan; says nothing about health. Funding and conflicts: Not stated in the abstract Read: abstract
Sovrani 2017 Structural characterization and rheological properties of a gel-like beta-d-glucan from Pholiota nameko. Carbohydrate Polymers · PMID 28504124 · DOI	Other n/a	Laboratory extracts	Cold-water extract (SCW) and purified glucan (bG-PN) of Pholiota nameko mushroom (part not stated in the abstract) Not shown here	The cold-water extract was mannose 24.1%, galactose 44.9% and glucose 31%. The purified fraction was only glucose: a (1-3)-linked beta-D-glucan with side chains. Both formed heat-stable gels, so the authors suggest it as a food thickener. Describes the gel-forming glucan Methods, limits and funding Outcomes: Sugar make-up, structure and gel behaviour Limitations: Chemistry only. Funding and conflicts: Not stated in the abstract Read: abstract
Sun 2026 Extraction, purification, structural characterization, bioactivities, and applications of Pholiota nameko polysaccharide: a review (RSC Advances, 2026; PMC13054809) RSC Advances · Source	Narrative review review	Review of laboratory and animal work on nameko polysaccharide	Pholiota nameko polysaccharide not separated here Not shown here	Summary-only: our earlier record says this review finds the effects mostly confined to preclinical work and that reports of clinical trials are scarce. We did not re-open it this round. Preclinical findings only; clinical trial reports scarce (summary-only) Methods, limits and funding Outcomes: Reported bioactivities and clinical evidence Limitations: Summary-only. Not re-opened on 2026-10-25. Funding and conflicts: Not checked Read: summary-only
Zhang 2020 A novel antitumor protein from the mushroom Pholiota nameko induces apoptosis of human breast adenocarcinoma MCF-7 cells in vivo and modulates cytokine secretion in mice bearing MCF-7 xenografts. International Journal of Biological Macromolecules · PMID 32858105 · DOI	Animal research animal	BALB/c mice carrying human MCF-7 breast-cancer cell implants	A purified protein (PNAP) from Pholiota nameko mushroom (part not stated in the abstract) Not shown here	The purified protein inhibited growth of the implanted tumours, switched on cell-death pathways in the tumour cells, and shifted the Th1/Th2 balance towards Th1. The authors call it a possible new approach for breast cancer. Slower growth of implanted human tumour cells in mice Methods, limits and funding Outcomes: Growth of implanted tumours; cell-death pathways; cytokines Limitations: A purified protein in mice with implanted human cells. Not the mushroom, not a person, and not a treatment. Funding and conflicts: Not stated in the abstract Read: abstract
Zhang 2022 Chemical properties and anti-fatigue effect of polysaccharide from Pholiota nameko. Journal of Food Biochemistry · PMID 34821398 · DOI	Animal research animal	Male and female mice in a forced-swim test	Pholiota nameko polysaccharide (PNP) mushroom (part not stated in the abstract) Not shown here	Forced swim time rose from 121.58 +/- 18.48 and 101.91 +/- 14.27 min to 154.95 +/- 24.26 and 134.13 +/- 25.71 min in male and female mice. LDH, Ca-Mg-ATPase and SOD activity were reported higher and MDA lower. Longer swim time in mice Methods, limits and funding Outcomes: Forced swim time and blood and tissue fatigue markers Limitations: One animal study; swim time in mice is not the same as tiredness in people. Funding and conflicts: Research support from a non-US government source per the PubMed record; no industry funding noted Read: abstract
Zheng 2014 Antihyperlipidemic and hepatoprotective activities of mycelia zinc polysaccharide from Pholiota nameko SW-02. International Journal of Biological Macromolecules · PMID 25077837 · DOI	Animal research animal	Mice made hyperlipidaemic with a high-fat emulsion	Zinc-enriched polysaccharide (MZPS) from mycelia of Pholiota nameko strain SW-02 mycelium grown in culture (zinc content 16.68 +/- 0.73 mg/g) Not shown here	Supplementing MZPS improved blood fats (TC, TG, HDL-C, LDL-C, VLDL-C), liver fats (TC, TG) and antioxidant markers (SOD, T-AOC, MDA, LPO). Liver pathology and the liver enzyme GPT suggested less liver cell injury. The authors say it might help lower fats and protect against fatty liver from a high-fat diet. Better blood-fat and liver measures in mice on a high-fat diet Methods, limits and funding Outcomes: Blood and liver fats, antioxidant status, liver injury Limitations: A zinc-enriched mycelium extract in mice. Different from the cooked fruiting body. No human data. Funding and conflicts: Research support from a non-US government source per the PubMed record; no industry funding noted Read: abstract
Zhou 2025 Extraction, structure and bioactivities of polysaccharides from Pholiota nameko: a review. Food Science and Biotechnology · PMID 41211565 · DOI	Narrative review review	Review of laboratory and animal work on nameko polysaccharides	Pholiota nameko polysaccharides (PNPS) fruiting body and mycelium extracts (not separated in the abstract) Not shown here	The review says PNPS are mainly glucose and mannose with some galactose, xylose and arabinose, and lists antioxidant, blood-fat-lowering and immune-regulating activity. The abstract mentions no human trials. Review lists lab and animal activities; no human trials mentioned Methods, limits and funding Outcomes: Extraction, structure and reported activities Limitations: Only the abstract was read. A review of preclinical work cannot show benefit in people. Funding and conflicts: Not stated in the abstract Read: abstract
n/a 2026 GBIF Backbone Taxonomy record: Pholiota microspora (Berkeley) Saccardo, key 9751347, checked by API 2026-10-25 n/a · Source	Database record n/a	n/a	n/a	ACCEPTED species, family Strophariaceae, order Agaricales, class Agaricomycetes, phylum Basidiomycota, kingdom Fungi. Methods, limits and funding Outcomes: Accepted name and family. Limitations: Identity record only; says nothing about safety or effects. Funding and conflicts: Independent public information source Read: full text
n/a 2026 GBIF Backbone Taxonomy record: Pholiota nameko (T.Itô) S.Ito & S.Imai, key 2534290, checked by API 2026-10-25 n/a · Source	Database record n/a	n/a	n/a	ACCEPTED species, published in Bot. Mag., Tokyo 47: 388 (1933), family Strophariaceae. Methods, limits and funding Outcomes: Accepted name, authority and family. Limitations: Identity record only; says nothing about safety or effects. Funding and conflicts: Independent public information source Read: full text

What we do not know yet

No human trial of nameko as a food or supplement.
No food-allergy report or allergy testing for eaten nameko, and no data on pregnancy, children or medicine interactions.
No regulator statement about nameko was found.
No source on look-alikes for wild nameko.
Food composition rests on single table entries and one factory sample.

How new research is added

New studies are found by a saved PubMed search and placed in a review queue. A person reads each one before it changes any evidence rating or safety wording. New publications never change ratings automatically.

Lab markers

What changed in blood or saliva tests during trials. A changed number is not the same as feeling or being healthier, and we give no "normal ranges".

Other 7

▼

CD40 and CD80 maturation markers (mouse cells)

Lowered in trials

Proteins on the surface of dendritic cells that rise when the cells switch on to alert other immune cells.

Not enough evidence

Results and what it means

Why it was measured

Used in the lab to see whether a substance calms or excites immune cells.

Statistical vs. clinical meaning

Statistical size is not given in the abstract.

Safety implication

None known. Cell work does not show effects in people.

Study	Result	People	Product
⁷	PNPS-1 decreased CD40 and CD80 expression on mouse bone marrow-derived dendritic cells; no figures in the abstract.	Mouse cells in dishes	Purified Pholiota nameko polysaccharide (PNPS-1)

⁷

▼

Pain behaviour in the mouse formalin test

Lowered in trials

How much a mouse licks or guards a paw after an irritant is injected. Used as a stand-in for inflammatory pain in animals.

Not enough evidence

Results and what it means

Why it was measured

A standard animal screen for pain-relieving or anti-inflammatory substances.

Statistical vs. clinical meaning

Dose-related fall in a mouse behaviour score; not tested in people.

Safety implication

None assessed in the abstract.

Study	Result	People	Product
¹	Inhibition of inflammatory pain behaviour of 24.8%, 56.9% and 82.3% at 0.3, 1.0 and 3.0 mg per kg.	Mice	Purified beta-D-glucan (GHW-PN) from Pholiota nameko

↕

Radical scavenging (ABTS and OH tests)

Mixed results in trials

Test-tube measures of how well a liquid neutralises unstable molecules called free radicals.

Not enough evidence

Results and what it means

Why it was measured

A quick lab screen for antioxidant potential.

Statistical vs. clinical meaning

Weak to modest in the lab; says nothing about the body.

Safety implication

None known.

Study	Result	People	Product
¹³	No strong antioxidant activity was observed, although extracts could scavenge ABTS and OH radicals.	Test tubes	Enzyme-made and ultrasound extracts of Pholiota nameko

¹³

↕

Blood and liver fats (mouse)

Mixed results in trials

Total cholesterol, triglycerides, HDL-C, LDL-C and VLDL-C in blood, and cholesterol and triglycerides in the liver, measured in mice.

Not enough evidence

Results and what it means

Why it was measured

Used to test whether a substance protects against fatty liver or high blood fats in animals.

Statistical vs. clinical meaning

Direction reported as improved; sizes not shown.

Safety implication

None assessed.

Study	Result	People	Product
²⁰	Blood fats (TC, TG, HDL-C, LDL-C, VLDL-C) and liver fats (TC, TG) were improved in mice on a high-fat diet; no figures in the abstract.	Mice on a high-fat emulsion	Zinc-enriched mycelium polysaccharide from Pholiota nameko SW-02

²⁰

▲

Forced swim time (mouse)

Raised in trials

How long a mouse keeps swimming before giving up.

Not enough evidence

Results and what it means

Why it was measured

A common animal screen for anti-fatigue claims.

Statistical vs. clinical meaning

Longer in both sexes; mouse test only.

Safety implication

None assessed.

Study	Result	People	Product
¹⁹	Swim time rose from 121.58 +/- 18.48 and 101.91 +/- 14.27 min to 154.95 +/- 24.26 and 134.13 +/- 25.71 min in male and female mice.	Male and female mice	Pholiota nameko polysaccharide (PNP)

¹⁹

↕

39 serum cytokines (route unclear)

Mixed results in trials

Messenger proteins released by immune cells, measured in serum.

Not enough evidence

Results and what it means

Why it was measured

A broad look at inflammation and immune signalling.

Statistical vs. clinical meaning

Cannot be judged from the abstract.

Safety implication

None assessed.

Study	Result	People	Product
⁶	Reported as significant anti-inflammatory activity across a network of 39 cytokines; the abstract gives no figures and does not say how volunteers were exposed.	Healthy volunteers' serum	Pholiota nameko polysaccharide PNPS-1

⁶

▼

Alpha-glucosidase blocking (test tube)

Lowered in trials

How much an extract slows an enzyme that breaks starch into sugar.

Not enough evidence

Results and what it means

Why it was measured

Screen for possible effects on blood sugar after meals.

Statistical vs. clinical meaning

Lab result only.

Safety implication

None known.

Study	Result	People	Product
¹³	30 to 50% inhibition by ultrasound, Flavourzyme and Cellulase extracts.	Test tubes	Extracts of Pholiota nameko

¹³

Safety

What studies and official sources say about side effects, medicines and who should check first. Each point shows what kind of evidence it comes from.

Main points to know 4

Breathing nameko spores while growing it can cause a lung allergy. Three Japanese case reports describe hypersensitivity pneumonitis, an immune inflammation of the lungs, in people who worked with or grew nameko: a 52-year-old worker in a cultivating room, a 49-year-old woman who grew it indoors for three years, and a 42-year-old farmer of 10 years. Symptoms were cough, fever and breathlessness. In the farmer's case the symptoms settled after he left the exposure and took a corticosteroid. Case reports show it can happen, not how often. All three involved breathing spores, not eating the mushroom. Case report ^{12 5 4}
No harm from eating nameko was found, but the evidence is thin. We found no case report of harm from eating cooked nameko, and no food-allergy report. Absence of reports is not proof of safety. No study was designed to test safety, and this page does not rest on any safety trial. Insufficient
Metals depend on where the mushroom was grown. Mushrooms take up metals from their growing medium. In a Beijing market survey nameko had relatively low metal levels, and in a Chinese online-supermarket survey its hazard quotients were below 1. In canned mushrooms sold in Spain, nameko carried 59.2% of the aluminium intake limit in the authors' model, which they call near the maximum. Survey ^{3 2 14}
Never pick wild mushrooms using this page. No source we read describes look-alikes for wild nameko, so this page cannot help you tell it from other wild fungi. If anyone has eaten a wild mushroom they cannot identify, call a poison centre straight away (in the US, Poison Help 1-800-222-1222) and do not wait for symptoms. Insufficient

Side effects 3

Effect	How often	Severity and recovery	Evidence
Hypersensitivity pneumonitis (lung allergy) from breathing spores Linked to growing rooms and indoor cultivation, not to eating.	Unknown. Three case reports in the literature we read; no rate	moderate to serious Settled after leaving the exposure and taking a corticosteroid in one report; outcomes in the others were not given in the abstracts	Case report ^{12 5 4}
Food allergy from eating nameko Not found in the literature searched. Mushroom allergy exists in general, so someone with a known mushroom allergy should ask their doctor first.	No report found	not known Not known	Insufficient
Metal intake (aluminium, cadmium, lead and others) Low in two surveys; aluminium near the limit in one model of canned nameko.	Depends on the product and the growing medium	not assessed as an effect; modelled intake only Not applicable	Survey ^{3 2 14}

Liver

No report of liver injury from nameko was found. A mouse study of a zinc-enriched mycelium extract reported less liver cell injury on a high-fat diet, which is not a safety study. ²⁰

Monitoring. No agency monitoring advice was read.

This is a safety connection. It is not evidence that Nameko supports liver health.

Medicines and supplements 2

With	Why it matters	Importance	Evidence	What to do
Prescription medicines, supplements and alcohol (any) other	Not studied for nameko as a food.	We read no source that documents an interaction with eating nameko, and no source that rules one out.	Insufficient Not enough evidence	If you take regular medicines, ask your pharmacist about any new mushroom product, especially concentrated extracts. Eating cooked nameko as a food is a different thing from an extract.
Corticosteroids and immune-suppressing medicines prescription	Not studied. Nameko polysaccharides changed immune-cell signalling in mouse cells in the lab only.	No human data. Not shown to matter for eating nameko.	Laboratory research Not enough evidence ⁷	People on immune-suppressing medicines can ask their doctor before using concentrated mushroom extracts.

Who should check first 4

Situation	Advice	Evidence
Growing nameko indoors or working in a growing room	If you develop cough, fever or breathlessness after handling the mushroom or its spores, see a clinician and mention the exposure.	Case report ^{12 5 4}
Known mushroom allergy	No nameko-specific allergy report was found, but ask a doctor before eating it.	Insufficient
Wild mushrooms you cannot identify	Do not eat them. No source we read lists nameko look-alikes.	Insufficient
Pregnancy, breastfeeding and young children	Not described in any source read for nameko. Normal food amounts of well-cooked mushrooms are not singled out as a risk by any source we read, but we have no study to confirm that. Ask a doctor before using concentrated extracts.	Insufficient

Overdose, product quality and regulators

Summary. Poisoning from eating cultivated nameko was not described in the sources we read. The documented problem is breathing spores in growing rooms.

Animal. No animal toxicology study of nameko was read.

Human doses studied. No human trial exists. This page gives no amounts.

High dose or long term signals. Not studied. Long-term effects of extracts are unknown.

Overdose response. No overdose description was found. For any poisoning concern call a poison centre.

Genotoxicity. Not read.

Toxic or hazardous parts. Fungus: the fruiting body is the part eaten. Spores are the part linked to lung allergy in growers. Mycelium extracts used in lab work are a different material.

Mushrooms can carry metals from their growing medium. Nameko is sold as a food, and no quality data on finished extracts were found.

Metals in Beijing markets. Cd, Pb and As in mushrooms rose with those in their medium. Nameko and Tremella had relatively low levels, and estimated weekly intake was lower than WHO/FAO limits. ³

Metals in a Chinese online supermarket. Nameko hazard quotients for five metals were below 1. ²

Aluminium in canned mushrooms from Spain. Aluminium in nameko samples reached 59.2% of the maximum intake in the authors' model, near the limit. ¹⁴

Extracts and supplements. No nameko supplement with human evidence and no quality testing of such products was found.

When to get medical help

Cough, fever and breathlessness developing hours after handling or growing nameko or other mushrooms indoors.
Any illness after eating a wild mushroom you could not identify: call a poison centre straight away and do not wait for symptoms.
Swelling of lips or face, wheeze, or hives after eating mushrooms: seek emergency care.

If someone may be poisoned or in a crisis, contact a clinician or emergency service straight away. In the US, Poison Control is 1-800-222-1222.

General information only, not medical advice. Ask a clinician or pharmacist before use, especially with medicines, in pregnancy or with a health condition. See the Natural Remedy Safety guide.

Frequently asked questions

What is nameko?

Nameko is a small amber-brown Japanese cooking mushroom with a slippery coating, used in miso soup and hot pots. Its Latin name is Pholiota microspora, also written Pholiota nameko.

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Is nameko safe to eat?

We found no report of harm or food allergy from eating cooked nameko, but we also found no safety study, so the evidence is thin. Anyone with a known mushroom allergy can ask a doctor first.

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Why is nameko slimy?

The cap is coated with a gel. One paper describes the mucilage as mainly pectin, and another found a beta-glucan in extracts that forms heat-stable gels.

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Does nameko have health benefits?

Not shown in people. We found no human trial. The research is lab and mouse work on purified extracts, and reviews say clinical trials are scarce.

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Can growing nameko at home cause problems?

Case reports describe lung inflammation in growers and mushroom workers who breathed the spores indoors. If you grow it and develop cough, fever or breathlessness, see a clinician and mention the exposure.

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Is nameko the same as Pholiota microspora?

Usually yes. GBIF lists both P. microspora and P. nameko as accepted species, and Japanese sources use P. microspora, so a label with either name usually means the cultivated slimy mushroom.

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Does nameko contain vitamin D?

Japan's food table lists 0 for raw nameko, and we found no value for UV-exposed nameko.

⁹

Does nameko contain heavy metals?

Mushrooms take up metals from where they grow. Nameko had relatively low levels in a Beijing survey and hazard quotients below 1 in a Chinese survey. In canned mushrooms from Spain, nameko supplied 59.2% of the aluminium limit in the authors' model.

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Can nameko interact with medicines?

We read no source that documents an interaction with eating nameko, and none that rules one out. If you take regular medicines, ask your pharmacist before adding concentrated mushroom extracts.

Is it safe in pregnancy or for children?

Not described in any source we read for nameko. Ask a doctor or midwife before using concentrated extracts.

Can I pick wild nameko?

Do not pick wild mushrooms using this page. No source we read lists look-alikes for wild nameko. If someone has eaten a wild mushroom they cannot identify, call a poison centre straight away; in the US that is Poison Help, 1-800-222-1222.

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Editorial transparency

Written by: AlternativeMed editorial team. Research compiled with AI assistance, then checked against PubMed records.
Medical review: None. This page has not been reviewed by a physician or pharmacist.
First published: 2026-10-25
Last substantive update: 2026-10-25
How we research: We read PubMed records and abstracts for 14 papers (three case reports, three food or metal surveys, seven laboratory, animal or chemistry papers and one review), and checked the species names in GBIF. Two more records (the 2023 Japanese food table and a 2026 Scientific Reports analysis) and one 2026 RSC Advances review were carried over from an earlier read and are marked summary-only. No regulator page for nameko was found. Numbers come from abstracts. Certainty ratings are the compiler's own reading.
How we rate evidence: See "How we rate evidence" in the Evidence tab.
Independence: No product is promoted on this page. No affiliate links are shown. This page is information, not a recommendation to use nameko.

Sources 23

Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.

Abreu H, Simas FF, Smiderle FR, et al. Gelling functional property, anti-inflammatory and antinociceptive bioactivities of beta-D-glucan from the edible mushroom Pholiota nameko.. International Journal of Biological Macromolecules. 2019. PMID 30218731. DOI 10.1016/j.ijbiomac.2018.09.062. (abstract)
Chen S, Guo Q, Zhou T, et al. Levels and health risk assessment of inorganic arsenic, methylmercury, and heavy metals in edible mushrooms collected from an online supermarket in China.. Biological Trace Element Research. 2024. PMID 37526876. DOI 10.1007/s12011-023-03779-w. (abstract)
Huang Q, Jia Y, Wan Y, et al. Market survey and risk assessment for trace metals in edible fungi and the substrate role in accumulation of heavy metals.. Journal of Food Science. 2015. PMID 26077507. DOI 10.1111/1750-3841.12923. (abstract)
Inage M, Takahashi H, Nakamura H, et al. Hypersensitivity pneumonitis induced by spores of Pholiota nameko.. Internal Medicine. 1996. PMID 8739786. (abstract)
Ishii M, Kikuchi A, Kudoh K, et al. Hypersensitivity pneumonitis induced by inhalation of mushroom (Pholiota nameko) spores.. Internal Medicine. 1994. PMID 7849381. (abstract)
Li H, Liu X, Li Y, et al. Effects of the polysaccharide from Pholiota nameko on human cytokine network in serum.. International Journal of Biological Macromolecules. 2012. PMID 22044749. DOI 10.1016/j.ijbiomac.2011.10.015. (abstract)
Li H, Tao Y, Zhao P, et al. Effects of Pholiota nameko polysaccharide on NF-kB pathway of murine bone marrow-derived dendritic cells.. International Journal of Biological Macromolecules. 2015. PMID 25812973. DOI 10.1016/j.ijbiomac.2015.03.011. (abstract)
Meng Y, Xue J, et al. Chemical composition, metabolomics, and functional potential of Pholiota nameko pre-cooking liquid. Scientific Reports. 2026. DOI 10.1038/s41598-026-35650-y. (summary-only)
Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. Standard Tables of Food Composition in Japan 2023 (8th revised edition, supplement): nameko, cluster-harvested, raw (food no. 08020). Government food composition table. 2023. (summary-only)
Moriwaki H, Ono K, Akiyama Y. Removal of microplastics or nanoplastics using nameko (Pholiota nameko) mucilage as a flocculant.. Chemosphere. 2026. PMID 41903317. DOI 10.1016/j.chemosphere.2026.144919. (abstract)
NARO (National Agriculture and Food Research Organization), Japan. Functional component content information, mushrooms (nameko, raw, n = 3). Government functional-component table. . (summary-only)
Nakazawa T, Tochigi T. Hypersensitivity pneumonitis due to mushroom (Pholiota nameko) spores.. Chest. 1989. PMID 2707072. (abstract)
Rodrigues D, Freitas AC, Sousa S, et al. Chemical and structural characterization of Pholiota nameko extracts with biological properties.. Food Chemistry. 2017. PMID 27596407. DOI 10.1016/j.foodchem.2016.08.030. (abstract)
Rubio C, Martinez C, Paz S, et al. Trace element and toxic metal intake from the consumption of canned mushrooms marketed in Spain.. Environmental Monitoring and Assessment. 2018. PMID 29564562. DOI 10.1007/s10661-018-6614-6. (abstract)
S Hirao A, Kumata A, Takagi T, et al. Japanese "nameko" mushrooms (Pholiota microspora) produced via sawdust-based cultivation exhibit severe genetic bottleneck associated with a single founder.. Mycoscience. 2022. PMID 37089630. DOI 10.47371/mycosci.2022.03.002. (abstract)
Sovrani V, de Jesus LI, Simas-Tosin FF, et al. Structural characterization and rheological properties of a gel-like beta-d-glucan from Pholiota nameko.. Carbohydrate Polymers. 2017. PMID 28504124. DOI 10.1016/j.carbpol.2017.03.093. (abstract)
Sun J, et al. Extraction, purification, structural characterization, bioactivities, and applications of Pholiota nameko polysaccharide: a review (RSC Advances, 2026; PMC13054809). RSC Advances. 2026. (summary-only)
Zhang Y, Zhang Y, Gao W, et al. A novel antitumor protein from the mushroom Pholiota nameko induces apoptosis of human breast adenocarcinoma MCF-7 cells in vivo and modulates cytokine secretion in mice bearing MCF-7 xenografts.. International Journal of Biological Macromolecules. 2020. PMID 32858105. DOI 10.1016/j.ijbiomac.2020.08.187. (abstract)
Zhang S, Liu B, Yan G, et al. Chemical properties and anti-fatigue effect of polysaccharide from Pholiota nameko.. Journal of Food Biochemistry. 2022. PMID 34821398. DOI 10.1111/jfbc.14015. (abstract)
Zheng L, Zhai G, Zhang J, et al. Antihyperlipidemic and hepatoprotective activities of mycelia zinc polysaccharide from Pholiota nameko SW-02.. International Journal of Biological Macromolecules. 2014. PMID 25077837. DOI 10.1016/j.ijbiomac.2014.07.037. (abstract)
Zhou X, Li H, Huang Y, et al. Extraction, structure and bioactivities of polysaccharides from Pholiota nameko: a review.. Food Science and Biotechnology. 2025. PMID 41211565. DOI 10.1007/s10068-025-01866-3. (abstract)
n/a. GBIF Backbone Taxonomy record: Pholiota microspora (Berkeley) Saccardo, key 9751347, checked by API 2026-10-25. n/a. 2026. (full text)
n/a. GBIF Backbone Taxonomy record: Pholiota nameko (T.Itô) S.Ito & S.Imai, key 2534290, checked by API 2026-10-25. n/a. 2026. (full text)

Where to buy

Check the label first. Whatever you buy, look for these:

Fruiting body versus mycelium on grain: the label should say which
The extract type and the beta-glucan amount, if stated
A third-party testing mark
Interactions: ask a pharmacist if you take medicines or blood thinners

Talk to a pharmacist or doctor before you start any supplement, especially if you take medicines. See the Safety tab for interactions.

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Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.