Shiitake, a brown-capped culinary and medicinal mushroom.

Mushrooms · Culinary and medicinal mushroom

Shiitake

Q: What is shiitake?

Shiitake (Lentinula edodes) is a mushroom, a fungus rather than a plant. It is a common food in East Asia and worldwide and is also sold as powders and extracts. Lentinan, a purified sugar-like substance from shiitake, is used as an injected medicine in Japan and China.

Q: Is shiitake safe to eat?

Cooked shiitake is an ordinary food. The main documented harm is a rash after eating it raw or undercooked, and MSK lists a few cases after cooked mushroom too. Other reports are rare: lung inflammation in mushroom workers who breathe in spores, and bowel blockage from swallowing a whole mushroom.

Q: What is shiitake dermatitis?

It is an itchy rash of red, raised, whip-like streaks, also called flagellate dermatitis. In a French poison-centre series of 59 cases, it appeared a median of 48 hours after raw or undercooked shiitake, lasted a median of 10 days, and every patient recovered. A review of 50 published cases found fever, diarrhoea or mouth ulcers in some people.

Q: Can I eat shiitake raw?

It is best not to. Raw and undercooked shiitake caused the rash in the French cases, and the authors say inadequate cooking seems to drive it. The rash can be very itchy and last weeks, though it is not described as dangerous. MSK says cases have also happened after cooked shiitake.

Q: Does shiitake boost the immune system?

In one small study, healthy adults who ate dried shiitake for 4 weeks showed changes in some immune-cell lab tests and a saliva antibody. There was no comparison group and nobody counted infections, so it does not show that shiitake prevents illness.

Q: What is lentinan, and is it the same as shiitake?

No. Lentinan is a purified beta-glucan taken out of shiitake and given as an injection by a care team, alongside chemotherapy, in Japan and China. Eating shiitake, or taking powder or extract capsules, is not the same. MSK says most lentinan studies used injections and that it is uncertain whether eating shiitake has similar effects.

Q: Does shiitake help against cancer?

Shiitake is not a cancer treatment. Injected lentinan added to chemotherapy was linked to better response and quality of life in a pooled analysis of 31 gastric cancer trials. For shiitake extracts, a 2026 review found a better response rate but no clear difference in survival, and said the evidence does not support firm recommendations.

Q: Does shiitake lower cholesterol?

It did in mice. In people the results are mixed: shiitake bars lowered triglycerides about 10% in one small trial, but a shiitake beta-glucan extract did not change cholesterol in another. MSK says there is no clinical proof in people.

Q: Does shiitake interact with medicines?

The sources we read show only one tested interaction: a shiitake-rich diet modestly raised kidney clearance of gabapentin, probably not important. MSK says chronic eating may raise the eosinophil count in blood tests. Cancer patients and people on immune-suppressing medicines should tell their team or pharmacist about any shiitake product.

Q: Is shiitake safe in pregnancy, breastfeeding or for children?

The sources we read do not address shiitake supplements in pregnancy, breastfeeding or children. Cooked shiitake in an ordinary meal is a different matter from powders and extracts, so ask a doctor, midwife or pharmacist about supplements. Young children should not be given whole pieces because of the bowel-blockage risk.

Lentinula edodes · also called Xiang gu, hua gu, forest mushroom, black forest mushroom

Shiitake is a popular food mushroom from East Asia that is also sold as powders and extracts. Small studies suggest it can change some immune lab tests, but none shows it prevents illness. Raw or undercooked shiitake can cause an itchy streaky rash. Lentinan, a purified part of shiitake, is a prescribed injection in Japan and China and is not the same as eating the mushroom.

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 Shiitake

Shiitake (Lentinula edodes) is a mushroom eaten and used as a tonic in East Asia. Research on eating shiitake is small: one study of immune lab tests, two small cholesterol trials with different results, and a few short studies. The stronger cancer-care findings are for injected lentinan, a purified medicine, and for extracts the evidence is weak. The most important safety point is the rash from raw or undercooked shiitake. None of this is a cure for any condition.

What it is

Shiitake is a fungus of the family Omphalotaceae, not a plant. The accepted name is Lentinula edodes; the older name Lentinus edodes appears in much of the research. It is grown widely and eaten fresh or dried.

Products include fruiting-body powder, hot-water or dual extracts, and mycelium grown on grain. These can differ a lot from each other and from the cooked mushroom.

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Lentinan: a medicine, not the mushroom

Lentinan is a purified beta-glucan taken out of shiitake. In Japan and China it is approved as an injection given with chemotherapy, and reviews say it is used for gastric cancer there. A pooled analysis of 31 gastric cancer trials found better response and quality of life when it was added. A pooled analysis of 17 lung cancer trials with a chest injection looked favourable too, but the reviewers rate those trials low quality.

These findings are about the injection. MSK says most lentinan studies used injections and it is uncertain whether eating shiitake has similar effects. Lentinan injections can cause reactions of their own, and they are given by clinicians only.

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What the research shows for eaten shiitake and extracts

In 52 healthy adults, 4 weeks of eating dried shiitake changed some immune-cell lab tests and a saliva antibody, and a blood inflammation marker fell. There was no comparison group. A 2026 review of shiitake extracts alongside cancer treatment found a better response rate but no clear difference in survival and called the evidence insufficient for firm recommendations.

For cholesterol, one small trial of shiitake bars found about 10% lower triglycerides while another, using a beta-glucan extract, found no change. Other uses (well-being, exercise, gut bacteria) rest on one small study each.

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At a glance

Traditional uses history, not proof

Used for thousands of years in Asia to improve general health (Zhang 2019).
Recorded in Chinese medicine to nourish the blood and qi (Zhou 2024).
Fresh and dried forms are common in East Asian cooking and the mushroom is valued as an anticancer agent (MSK).

Studied for research

Immune lab markers when eaten, very low
Injected lentinan with chemotherapy in gastric cancer (a prescribed medicine), moderate
Shiitake extracts alongside cancer treatment, low
Cholesterol and blood fats, mixed
Well-being, gut bacteria and exercise recovery, very low to insufficient

Main compounds

Lentinan, a beta-glucan; purified for the injection
Eritadenine, which lowered cholesterol in animals
Ergothioneine, an antioxidant amino acid from food
Ergosterol, which becomes vitamin D2 under UV light

Common forms

Fresh or dried mushroom, cooked (food)
Fruiting-body powder
Hot-water or dual extracts
Mycelium grown on grain
Purified lentinan injection (a prescription medicine, given by a care team)

Research links: Memorial Sloan Kettering: Shiitake mushroom · NCI: Medicinal mushrooms (PDQ) · PubMed: Shiitake dermatitis, French poison centres (2022) · PubMed: Injectable lentinan in gastric cancer, meta-analysis (2024) · Research Library · Genes & Biomarkers Library

What it is and its history

Accepted scientific name: Lentinula edodes
Naming authority: (Berk.) Pegler (GBIF)
Synonyms: Lentinus edodes (Berk.) Singer (older name; a synonym in GBIF; used in much of the research); Agaricus edodes Berk. (original name, a synonym in GBIF); Lentinus shiitake (J.Schröt.) Singer (synonym in GBIF); Tricholoma shiitake (J.Schröt.) Lloyd (synonym in GBIF)
Common names: Shiitake (Japanese); Xiang gu / Xianggu (Chinese); Hua gu (Chinese (listed by MSK)); Forest mushroom; black forest mushroom (English)
Family or group: Omphalotaceae (a fungus family), not a plant
Classification: Fungi > Basidiomycota > Agaricomycetes > Agaricales > Omphalotaceae > Lentinula > Lentinula edodes
Native range: MSK says it is native to East Asia and cultivated worldwide.
Habitat: Not checked in the sources read.
What it looks like: Fruiting body: Not checked in the sources read.
Cultivation: Zhang 2019 calls it the second largest cultivated and the most popular edible mushroom in the world (abstract wording). Details were not checked.
Harvest and processing: Fresh and dried forms are used (MSK). Dried shiitake is more concentrated per 100 g because the water is removed (our nutrient summary).
Look-alikes and adulterants: Name: Wild mushrooms in general; Note: The sources we read give no shiitake look-alike list. Shiitake sold in shops is cultivated. Do not pick wild mushrooms without expert identification.
Sustainability and conservation: Not checked.

Traditional use and history history, not clinical proof

Tradition or era	Documented use	Source
East Asia (China and Japan)	Zhang 2019 says Lentinula edodes has been used to improve general health for thousands of years in Asia. Zhou 2024 says it has been recorded in Chinese medicine to nourish the blood and qi. MSK says the fresh and dried forms are commonly used in East Asian cooking and that it is valued as an anticancer agent.	p31030752
Modern medicine (lentinan)	Zhang 2019 says the antitumour property of lentinan was reported in the 1960s and that it has been approved as an add-on cancer medicine in China and Japan since the 1980s.	p31030752

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
Lentinan (beta-1,3-glucan with beta-1,6 branches)	polysaccharide	Fruiting body (purified for the medicine)	Described by MSK as a biological response modifier that does not kill cancer cells directly in lab tests but acts on the immune system. Heat-sensitive; thought to be involved in shiitake dermatitis. ^{23 3}	Laboratory research
Eritadenine	alkaloid (adenosine analog)	Fruiting body Our nutrient summary quotes 3.2 to 6.3 mg per g of dried mushroom second-hand from a paper we did not open (summary-only).	Lowered cholesterol in animals; no human trial of eritadenine itself was found. ¹⁷	Animal research
Ergothioneine	amino acid derivative (antioxidant)	Fruiting body Our nutrient summary notes that USDA and a 2026 Canadian survey disagree about five-fold on fresh shiitake (summary-only; not re-opened).	People get it only from food. A shiitake diet raised plasma ergothioneine for more than 48 hours in 10 men. ^{14 15}	Human lab measure
Ergosterol (becomes vitamin D2 under UV light)	sterol	Fruiting body Our nutrient summary says ordinary USDA shiitake records show only small amounts of vitamin D2 unless the mushroom was exposed to UV light (summary-only).	Turns into vitamin D2 when exposed to ultraviolet light or sunshine (lab work). No human study of UV-exposed shiitake was found. ¹⁵	Laboratory research

Mechanisms, receptors and pathways

Target or pathway	Gene or receptor	What was found	Level
Immune cell activation by beta-glucans	Lab work; MSK mentions effects on cytokines and immune cells	In human blood cells grown in the lab after 4 weeks of eating dried shiitake, gamma-delta T and NK-T cells grew more and some cytokines changed. Eaten shiitake changed these lab measures in healthy adults, but no health outcome was measured. ⁴	Human lab measure
Liver cholesterol handling (CYP7A1 gene)	CYP7A1	In mice on a high-fat diet, shiitake and eritadenine raised activity of CYP7A1, lowered blood fats and reduced liver fat. ¹⁷	Animal research
Kidney transporter for gabapentin (OCTN1)	OCTN1 (SLC22A4)	The authors cite lab work in which ergothioneine stimulates the secretion of gabapentin through this transporter; the human study showed a modest rise in gabapentin kidney clearance after a shiitake diet. ¹⁴	Human lab measure
Antiviral and antibacterial effects	Not specified	MSK describes effects on virus replication in cell cultures and antibacterial effects in mice. Lab and animal work only. ²³	Laboratory research

Absorption, metabolism and elimination

Absorption: Not found in the sources read, other than that plasma ergothioneine rose after a shiitake meal.
Distribution: Not found in the sources read.
Metabolism: Not found in the sources read.
Elimination: Plasma ergothioneine stayed raised for more than 48 hours (Toh 2014).
Bioavailability: Not established for lentinan taken by mouth. MSK says most lentinan studies used injections and that it is uncertain whether eating shiitake has similar effects.

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Isolated compounds versus whole extracts

Shiitake comes in several quite different forms: cooked fresh or dried mushroom (a food), fruiting-body powder, hot-water or dual extracts, mycelium grown on grain, and purified lentinan injection (a prescription medicine in Japan and China). Research on one form cannot be carried over to the others. In particular, the cancer-care results for the injection do not apply to the mushroom or to capsules, and the well-being trial used a branded mycelium beta-glucan.

Nutritional composition

Cooked shiitake is an ordinary food. Our nutrient summary lists fibre, potassium, copper, selenium and B vitamins from USDA records and notes dried shiitake is more concentrated per 100 g because the water is removed. This was taken from our own earlier summary and not re-opened for this page (summary-only). It shows what is in the food, not a proven health effect.

11benefits and uses looked at

23studies and sources checked

Moderate certaintybest evidence rating found

9lab markers tracked in trials

1 moderate certainty1 mixed findings2 low certainty3 very low certainty4 not enough evidence

What was looked at

The 11 benefits and uses checked for Shiitake, each with how strong the evidence is. Tap one to open it.

Immune markers when shiitake is eatenVery low certainty
Injected lentinan with chemotherapy: gastric cancer (a prescribed medicine)Moderate certainty
Lentinan with cisplatin chest injection: lung cancer (a prescribed treatment)Low certainty
Shiitake extracts alongside cancer treatmentLow certainty
Cholesterol and blood fatsMixed findings
Gut bacteriaNot enough evidence
Well-being scoresVery low certainty
Exercise recovery and inflammationVery low certainty
Ergothioneine from eating shiitakeNot enough evidence
Injected lentinan in HIV (small 1998 trials)Not enough evidence
Antiviral and antibacterial effectsNot enough evidence

Lab markers tracked in the studies

Immune-cell growth in the lab (gamma-delta T and NK-T cells)Saliva secretory IgA and blood C-reactive proteinTumour response rate with add-on shiitake productsCD3+, CD4+, CD4+/CD8+ and NK cells with injected lentinanBlood triglyceridesTotal cholesterol and LDL cholesterolAntioxidant markers (glutathione, thiol status)Blood ergothioneineSelf-rated well-being score

What is Shiitake good for?

The uses people ask about and how strong the human evidence is for each. None is proven for eaten shiitake. The lentinan injection results are for a hospital medicine and do not carry over to the mushroom. Read this together with the Safety tab.

Immune markers when shiitake is eatenVery low certaintyHealthy young adults who ate dried shiitake daily for 4 weeks had changes in some immune-cell lab tests and in a saliva antibody, and a blood inflammation marker fell. There was no comparison group and nobody counted infections. Injected lentinan with chemotherapy: gastric cancer (a prescribed medicine, not the mushroom)Moderate certaintyA pooled analysis of 31 trials found better treatment response and quality of life when injected lentinan was added to chemotherapy. It is approved as an add-on in Japan and China. This applies to the purified injection given by a care team only, not to shiitake food, powder or capsules. Lentinan with cisplatin chest injection: lung cancer (hospital treatment)Low certaintySeventeen trials pooled showed higher response and quality-of-life scores, but the reviewers rate the trials as low quality with a high risk of bias. Shiitake extracts alongside cancer treatmentLow certaintyTwenty-two trials: a better tumour response rate but no clear difference in survival, side effects or quality of life. The authors say the evidence does not support firm recommendations. Not a cancer treatment. Cholesterol and blood fatsMixed findingsShiitake lowered blood fats in mice. In people, one small trial of shiitake bars found about 10% lower triglycerides, but a trial of a shiitake beta-glucan extract found no change in cholesterol. Gut bacteriaNot enough evidenceOne trial found a shiitake beta-glucan extract changed the mix of gut bacteria. The authors could not say what that means for health. Well-being scoresVery low certaintyA 4-week trial of a branded shiitake mycelium beta-glucan found higher self-rated well-being than placebo. The product's maker is named in the abstract. Exercise recovery and inflammationVery low certaintyA shiitake extract did not reduce inflammation markers after hard exercise in healthy men; some antioxidant markers changed. Ergothioneine from eating shiitakeNot enough evidenceA shiitake meal raised blood ergothioneine, an antioxidant amino acid from food, for more than 48 hours in 10 men. No health benefit was measured. Injected lentinan in HIV (two small 1998 trials)Not enough evidenceGenerally tolerated when given slowly, with a CD4 trend that was not statistically significant. Not a treatment for HIV. Antiviral and antibacterial effectsNot enough evidenceSeen in lab and animal work only. MSK says clinical data are lacking.

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 markers when shiitake is eaten

Very low certainty

In one small study, healthy young adults who ate dried shiitake every day for 4 weeks had changes in some immune-cell lab tests and in a saliva antibody, and a blood inflammation marker went down. There was no placebo group, and the study did not count infections.

2 studiesWhole dried mushroom, eaten. The trial compared two intake levels wit…

Studies, doses and limits

What the trials found

Fifty-two healthy adults aged 21 to 41 ate whole dried shiitake daily for 4 weeks at one of two intake levels. Immune cells taken from their blood grew more in the lab afterwards (gamma-delta T cells 60% more, NK-T cells about 2-fold more), saliva secretory IgA rose and C-reactive protein fell. The pattern of cytokines changed, with some up and one down. MSK repeats these findings and lists them as a small randomised study.

Results

gamma-delta T cell growth +60%, NK-T cell growth about 2-fold, sIgA up, CRP down (no placebo group)

Effect sizes as reported

Changes in lab markers; no illness outcome

Why this rating

One small trial in healthy young adults, only 4 weeks, with no placebo or untreated group. The measures are lab markers, not fewer infections.

Form and dose studied

Whole dried mushroom, eaten. The trial compared two intake levels with each other. No amounts are advised here.

Who was studied

Healthy adults aged 21 to 41

Limits

No comparison group without mushrooms. Immune markers do not show better protection. Nobody counted colds or infections.

Why researchers looked

Shiitake beta-glucans (the fibre-like sugars in the cell wall) are known to act on immune cells in the lab, and the mushroom is eaten widely, so researchers asked whether eating it changes immune measures.

Traditional use

Used as a food and medicine in East Asia for a very long time. Zhang 2019 says it has been used to improve general health for thousands of years in Asia.

Proposed mechanism Laboratory research

Beta-glucans bind receptors on immune cells in lab work. This is a laboratory finding, not proof of a health effect.

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

Eat shiitake cooked through: raw or undercooked shiitake can cause a rash (see the Safety tab).

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Injected lentinan with chemotherapy: gastric cancer (a prescribed medicine)

Moderate certainty

Lentinan is a purified sugar-like substance taken out of shiitake. In Japan and China it is approved as an injection given with chemotherapy. A pooled analysis of 31 trials found better treatment response and quality of life when it was added. This is a hospital medicine, not eating shiitake and not a capsule.

4 studiesPurified lentinan injection given by a care team. Not the same as shi…

Studies, doses and limits

What the trials found

Wang 2024 pooled 31 randomised trials (2,729 people with gastric cancer). Adding injected lentinan to chemotherapy was linked to better treatment response (RR 1.48), better quality of life (RR 1.32), higher CD3+, CD4+, CD4+/CD8+ and NK cells, and less white blood cell and platelet decline than chemotherapy alone. The authors saw no serious adverse effects and graded the evidence for these outcomes high or moderate. Ina 2013 says it is approved in Japan for gastric cancer and that studies suggest longer survival in advanced disease. Zhou 2024 says it is approved as a chemotherapy add-on in China and Japan.

Results

Response RR 1.48 (95% CI 1.36 to 1.61); quality of life RR 1.32 (1.20 to 1.45)

Effect sizes as reported

Better response rate and quality-of-life scores than chemotherapy alone

Why this rating

The authors' own GRADE rating was high or moderate for these outcomes and the pooled trials point the same way. We lowered it to moderate because we read only the abstract, the authors ask for more trials, and survival is mainly described in a review rather than checked by us.

Form and dose studied

Purified lentinan injection given by a care team. Not the same as shiitake food, powder or extract capsules.

Who was studied

People with gastric cancer having chemotherapy

Limits

These results come from the purified injection. They cannot be carried over to eating shiitake or taking supplements. MSK says most lentinan studies used injections and that it is uncertain whether eating shiitake has similar effects.

Why researchers looked

Lentinan was studied as a 'biological response modifier': it does not kill cancer cells directly in the lab but affects immune cells (MSK).

Traditional use

Not a traditional use. Zhang 2019 says the anti-tumour property of lentinan was first reported in the 1960s and that it has been approved as an add-on cancer medicine in China and Japan since the 1980s.

Proposed mechanism Laboratory research

Lentinan is a beta-glucan. MSK says that in the lab it does not kill cancer cells directly but acts on the immune system. Treated as a lab finding.

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

Injected lentinan has its own reported reactions (see the Safety tab). It is only given by clinicians.

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Lentinan with cisplatin chest injection: lung cancer (a prescribed treatment)

Low certainty

Seventeen trials tested lentinan injected into the chest together with the chemotherapy drug cisplatin in lung cancer. Pooled results looked favourable, but the reviewers say the trials were of low quality.

2 studiesLentinan injection into the chest with cisplatin (hospital treatment).

Studies, doses and limits

What the trials found

A 2021 review of 17 randomised trials (1,390 people with non-small cell lung cancer) found higher clinical efficacy (RR 1.34) and quality of life (RR 1.48) with lentinan plus cisplatin than cisplatin chest injection alone, with fewer gastrointestinal reactions and less bone marrow suppression. The authors say methodological quality was low and the risk of bias high. A 2019 review of 135 studies from China (about 9,474 cases) also concluded lentinan improved quality of life and the benefit of chemotherapy and radiotherapy, but it gives no study-quality details in the abstract.

Results

Efficacy RR 1.34 (1.21 to 1.48); quality of life RR 1.48 (1.27 to 1.72)

Effect sizes as reported

Higher response and quality-of-life scores in low-quality trials

Why this rating

The reviewers of the lung trials rate the methods low quality with a high risk of bias, so the benefit is uncertain.

Form and dose studied

Lentinan injection into the chest with cisplatin (hospital treatment).

Who was studied

People with non-small cell lung cancer; wider cancer groups in the 2019 review

Limits

Low-quality trials. Does not apply to eaten shiitake or supplements.

Why researchers looked

Lentinan has been used as an add-on in cancer care in China and Japan, and lung cancer is one of the cancers where it has been used most often (Zhang 2019).

Traditional use

Not a traditional use.

Proposed mechanism Laboratory research

Same as above: lab work suggests lentinan acts on immune cells.

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

Hospital treatment only.

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Shiitake extracts alongside cancer treatment

Low certainty

A 2026 review of 22 trials of shiitake extracts added to standard cancer treatment found a better tumour response rate but no clear difference in survival, side effects or quality of life. The authors say the evidence does not support firm recommendations. Extracts are not a cancer treatment.

2 studiesDifferent extract products between trials; not detailed in the abstra…

Studies, doses and limits

What the trials found

In the 13 randomised trials, the response rate was better with the extract (odds ratio 1.45, 95% CI 1.01 to 2.07). Overall survival did not differ (HR 0.66, 95% CI 0.34 to 1.28), and neither did side effects or quality of life. Nine non-randomised trials looked more favourable. MSK adds that a shiitake extract was not effective for prostate cancer in one trial.

Results

Response OR 1.45 (1.01 to 2.07); survival HR 0.66 (0.34 to 1.28)

Effect sizes as reported

Modest tumour response signal; survival unclear

Why this rating

A mixed group of products, a response result that only just excludes 1, no survival difference, and non-randomised trials that look better than randomised ones. The authors say the evidence does not support clear recommendations.

Form and dose studied

Different extract products between trials; not detailed in the abstract.

Who was studied

People with various cancers having standard treatment

Limits

Many different products and cancers. Only the abstract was read.

Why researchers looked

People with cancer often ask about mushroom extracts, so reviewers pooled the trials that tested them alongside standard care.

Traditional use

MSK lists shiitake as valued as an anticancer agent in East Asian traditions.

Proposed mechanism Laboratory research

Not established. Lab work on lentinan and other shiitake compounds suggests effects on immune cells.

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

People having cancer treatment should tell the oncology team and pharmacist about any shiitake product before using it.

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Cholesterol and blood fats

Mixed findings

Shiitake lowered blood fats in mice. In people, one small trial of shiitake bars found about 10% lower triglycerides, while another trial of a shiitake beta-glucan extract found no change in cholesterol. MSK says there is no clinical proof that shiitake lowers cholesterol in people.

4 studiesShiitake food bars in one trial and a beta-glucan extract in the othe…

Studies, doses and limits

What the trials found

Spim 2021 (68 people with borderline high cholesterol, placebo-controlled, shiitake bars, about 66 days) found triglycerides 10% lower in the shiitake group (P = 0.0352) and better antioxidant markers; the abstract does not report LDL or total cholesterol change. Morales 2021 (52 adults with mild high cholesterol, 8 weeks, beta-glucan-enriched shiitake extract) found no significant difference in lipid or cholesterol measures versus placebo.

Results

Triglycerides about 10% lower (bars); no lipid change (extract)

Effect sizes as reported

One small lowering of triglycerides; one null trial

Why this rating

Two small human trials point different ways, with different products (bars versus a beta-glucan extract). Mouse results do not carry over to people.

Form and dose studied

Shiitake food bars in one trial and a beta-glucan extract in the other. No amounts are advised here.

Who was studied

Adults with borderline high or mild high cholesterol

Limits

Small trials, different products, short duration. Not a replacement for cholesterol care.

Why researchers looked

Shiitake contains eritadenine, which lowered cholesterol in animals, so researchers tested the mushroom in people with raised blood fats.

Traditional use

No traditional cholesterol use was found in the sources read.

Proposed mechanism Animal research

In mice, shiitake and eritadenine raised activity of the liver gene CYP7A1 and reduced liver fat and artery plaque. Animal finding only.

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

In the bar trial the abstract reports dermatitis in people who were sensitive to the mushroom.

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Gut bacteria

Not enough evidence

In one trial, a shiitake beta-glucan extract changed the mix of bacteria in the gut compared with placebo. The authors could not say what that change means for health.

1 studiesA shiitake beta-glucan-enriched extract in creams (one trial).

Studies, doses and limits

What the trials found

In 52 adults with mild high cholesterol, 8 weeks of a shiitake beta-glucan extract changed the composition of gut bacteria compared with placebo, with several bacteria groups correlating with cholesterol-related markers. Cholesterol and inflammation markers did not change. The extract was reported safe.

Results

Change in bacterial community composition; no clinical benefit shown

Effect sizes as reported

Not given in the abstract

Why this rating

One small trial; the abstract says the significance of the change was not fully worked out.

Form and dose studied

A shiitake beta-glucan-enriched extract in creams (one trial).

Who was studied

Adults with mild high cholesterol

Limits

One trial, no health outcome.

Why researchers looked

Beta-glucans are fibre-like sugars that gut bacteria can feed on.

Proposed mechanism Human lab measure

Beta-glucans reach the large bowel, where bacteria can use them. The trial linked some bacteria groups to cholesterol-related markers. A change in bacteria is a lab finding, not proof of a benefit.

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

Reported safe in this trial; trial too small to rule out rare reactions.

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Well-being scores

Very low certainty

A 4-week trial of a branded shiitake mycelium beta-glucan product found higher self-rated well-being than placebo, mostly in people who started with lower scores. The product's maker is named in the abstract.

1 studiesA branded mycelium-derived beta-glucan, not the whole mushroom.

Studies, doses and limits

What the trials found

In 63 healthy adults, a branded beta-glucan made from shiitake mycelium gave a statistically significant improvement in a well-being questionnaire compared with placebo after 4 weeks. The improvement was bigger when starting well-being was lower.

Results

Higher questionnaire score than placebo (figures not in the abstract)

Effect sizes as reported

Not given in the abstract

Why this rating

One short trial, self-reported scores, one branded product, possible industry link.

Form and dose studied

A branded mycelium-derived beta-glucan, not the whole mushroom.

Who was studied

Healthy adults

Limits

Questionnaire answers are easily influenced by expectation. Results are for one product only.

Why researchers looked

The product maker wanted to see whether the beta-glucan changed how well healthy adults felt.

Proposed mechanism Unknown

Not established.

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

None reported in the abstract.

Exercise recovery and inflammation

Very low certainty

A shiitake extract did not reduce inflammation markers after a long, hard run in healthy men, although some antioxidant markers changed.

1 studiesA shiitake extract (one study).

Studies, doses and limits

What the trials found

In a crossover study in healthy men, 10 days of shiitake extract before a 90-minute run with a downhill phase had no effect on immune-cell numbers or inflammatory mediators, except IL-10. Thiol redox status and nitric oxide rose.

Results

No change in most inflammation markers; nitric oxide and thiol status up

Effect sizes as reported

Not given in the abstract

Why this rating

A small crossover study measuring lab markers only; the main inflammation result was null.

Form and dose studied

A shiitake extract (one study).

Who was studied

Healthy men

Limits

Number of participants is not given in the abstract; no performance or recovery outcomes.

Why researchers looked

Shiitake contains ergothioneine, an antioxidant amino acid, so researchers asked whether it would limit the damage after hard exercise.

Proposed mechanism Human lab measure

The authors suggest changes in nitric oxide and thiol (antioxidant) status. Lab-measure finding.

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

None reported in the abstract.

¹⁸

Ergothioneine from eating shiitake

Not enough evidence

Shiitake is a food source of ergothioneine, an antioxidant amino acid. A small study showed that a shiitake meal raised ergothioneine in the blood for more than 48 hours. Whether that does anything for health is not shown.

2 studiesCooked shiitake eaten as part of a diet.

Studies, doses and limits

What the trials found

In 10 healthy men, a diet rich in shiitake raised plasma ergothioneine for more than 48 hours. Our nutrient summary (USDA records and a 2026 survey) notes that measured amounts in fresh shiitake differ about five-fold between sources; we did not re-open those records.

Results

Plasma ergothioneine raised after a shiitake diet

Effect sizes as reported

Not given in the abstract

Why this rating

The raised blood level is shown, but no health outcome was measured.

Form and dose studied

Cooked shiitake eaten as part of a diet.

Who was studied

Ten healthy men

Limits

A blood level is not a benefit.

Why researchers looked

People get ergothioneine only from food, and mushrooms are among the richer sources.

Proposed mechanism Human lab measure

Ergothioneine is taken up into the body and stays in the blood for days. Whether this protects cells is a lab hypothesis here.

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

See the interaction note for gabapentin on the Safety tab.

^{14 15}

Injected lentinan in HIV (small 1998 trials)

Not enough evidence

Two small trials gave HIV-positive people lentinan by vein. Side effects were mostly mild with a slow infusion, and CD4 cells trended upward without reaching statistical significance. It is not a treatment for HIV.

2 studiesPurified lentinan by injection into a vein (not food, not a supplemen…

Studies, doses and limits

What the trials found

In 98 HIV-positive people with CD4 counts of 200 to 500, lentinan by injection into a vein for 8 to 12 weeks was generally well tolerated, with a trend towards more CD4 cells that was not statistically significant. A quicker 10-minute infusion produced more serious side effects than a 30-minute one.

Results

CD4 trend, not statistically significant

Effect sizes as reported

Trend only

Why this rating

Two small phase I/II trials; no significant effect; no later confirming trial in the sources read.

Form and dose studied

Purified lentinan by injection into a vein (not food, not a supplement).

Who was studied

HIV-positive adults

Limits

Old, small, injection only.

Why researchers looked

Lentinan acts on immune cells in the lab, so it was tried in people with HIV.

Traditional use

Not a traditional use.

Proposed mechanism Laboratory research

Lab work suggests effects on immune cells. MSK says it is unclear whether lentinan or shiitake works for AIDS.

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

The faster infusion had more serious reactions, including an anaphylactoid reaction. See the Safety tab.

^{6 23}

Antiviral and antibacterial effects

Not enough evidence

In laboratory tests and animal studies, shiitake extracts and lentinan have shown antiviral and antibacterial effects. MSK says clinical data are lacking. Nothing here shows shiitake treats or prevents an infection in people.

1 studiesNot applicable

Studies, doses and limits

Results

No human results

Why this rating

Lab and animal work only.

Limits

Cell and mouse work does not show a benefit in people.

Why researchers looked

Lab and animal findings led to interest.

Proposed mechanism Laboratory research

MSK describes effects on virus replication in cell cultures and antibacterial effects in mice. Lab and animal work only.

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

Do not use shiitake in place of treatment for an infection.

²³

Connections to the rest of health

How Shiitake 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	Very low certainty	Immune markers when shiitake is eaten: In one small study, healthy young adults who ate dried shiitake every day for 4 weeks had changes in some immune-cell lab tests and in a saliva antibody, and a blood inflammation marker went down. There was no placebo group, and the study did not count infections.	^{4 23}
Cholesterol Balance	Preliminary mechanism	Mixed findings	Cholesterol and blood fats: Shiitake lowered blood fats in mice. In people, one small trial of shiitake bars found about 10% lower triglycerides, while another trial of a shiitake beta-glucan extract found no change in cholesterol. MSK says there is no clinical proof that shiitake lowers cholesterol in people.	^{13 8 17 23}
Gut Health	Preliminary mechanism	Not enough evidence	Gut bacteria: In one trial, a shiitake beta-glucan extract changed the mix of bacteria in the gut compared with placebo. The authors could not say what that change means for health.	⁸
Daily Vitality	Preliminary mechanism	Very low certainty	Well-being scores: A 4-week trial of a branded shiitake mycelium beta-glucan product found higher self-rated well-being than placebo, mostly in people who started with lower scores. The product's maker is named in the abstract.	¹
Muscle Recovery	Preliminary mechanism	Very low certainty	Exercise recovery and inflammation: A shiitake extract did not reduce inflammation markers after a long, hard run in healthy men, although some antioxidant markers changed.	¹⁸

B. Body systems

Connected to	Kind of connection	Evidence status	Context	Studies
Immune system	Preliminary mechanism	Very low certainty	Lab markers changed in a small study; injected lentinan is an approved add-on in Japan and China. Preparation or compound: Eaten dried shiitake; injected lentinan is separate	^{4 16}
Immune System	Biological association	Very low certainty	Studied for: Immune markers when shiitake is eaten Studied for: Injected lentinan with chemotherapy: gastric cancer (a prescribed medicine)	^{4 23 16 7 21 20 19 12 6}
Respiratory System	Biological association	Low certainty	Studied for: Lentinan with cisplatin chest injection: lung cancer (a prescribed treatment)	^{20 19}
Cardiovascular System	Biological association	Mixed findings	Studied for: Cholesterol and blood fats	^{13 8 17 23}
Digestive System	Biological association	Not enough evidence	Studied for: Gut bacteria	⁸
Musculoskeletal System	Biological association	Very low certainty	Studied for: Exercise recovery and inflammation	¹⁸

C. Body parts and organs

Connected to	Kind of connection	Evidence status	Context	Studies
Skin	Adverse effect or risk	Moderate certainty	Flagellate (whip-like) itchy rash; all recovered in a French series of 59 cases. Flagellate rash; all recovered in a French series of 59 cases. Preparation or compound: Raw or undercooked shiitake mushroom	^{3 9}
Lungs	Adverse effect or risk	Low certainty	Hypersensitivity pneumonitis in mushroom workers (case reports). Preparation or compound: Inhaled shiitake spores	^{2 23}
Small intestine	Adverse effect or risk	Low certainty	Small bowel obstruction case reports. Preparation or compound: Whole mushroom swallowed	²³

I. Biomarkers

Connected to	Kind of connection	Evidence status	Context	Studies
Immune-cell growth in the lab (gamma-delta T and NK-T cells)	Biological association	Very low certainty	Measured in trials: raised. A lab change is not the same as a health benefit.	⁴
Saliva secretory IgA and blood C-reactive protein	Biological association	Very low certainty	Measured in trials: raised (IgA) and lowered (CRP). A lab change is not the same as a health benefit.	⁴
Tumour response rate with add-on shiitake products	Biological association	Low certainty	Measured in trials: raised. A lab change is not the same as a health benefit.	^{16 12}
CD3+, CD4+, CD4+/CD8+ and NK cells with injected lentinan	Biological association	Moderate certainty	Measured in trials: raised (CD8+ lowered). A lab change is not the same as a health benefit.	¹⁶
Blood triglycerides	Biological association	Low certainty	Measured in trials: lowered (bars); not studied or unchanged elsewhere. A lab change is not the same as a health benefit.	¹³
Total cholesterol and LDL cholesterol	Biological association	Low certainty	Measured in trials: unchanged. A lab change is not the same as a health benefit.	⁸
Antioxidant markers (glutathione, thiol status)	Biological association	Very low certainty	Measured in trials: raised. A lab change is not the same as a health benefit.	^{13 18}
Blood ergothioneine	Biological association	Low certainty	Measured in trials: raised. A lab change is not the same as a health benefit.	¹⁴
Self-rated well-being score	Biological association	Very low certainty	Measured in trials: raised. A lab change is not the same as a health benefit.	¹

J. Genes, receptors and enzymes

Connected to	Kind of connection	Evidence status	Context	Studies
CYP7A1	Preliminary mechanism	Animal	Liver cholesterol-handling gene raised by shiitake in mice.	¹⁷

K. Biological pathways

Connected to	Kind of connection	Evidence status	Context	Studies
OCTN1 (SLC22A4)	Preliminary mechanism	Human lab measure	Ergothioneine and gabapentin transporter named by the authors of the gabapentin study.	¹⁴

L. Active compounds

Connected to	Kind of connection	Evidence status	Context	Studies
Lentinan (beta-1,3-glucan with beta-1,6 branches)	Biological association	In vitro	Described by MSK as a biological response modifier that does not kill cancer cells directly in lab tests but acts on the immune system. Heat-sensitive; thought to be involved in shiitake dermatitis. Preparation or compound: Fruiting body (purified for the medicine)	^{23 3}
Eritadenine	Biological association	Animal	Lowered cholesterol in animals; no human trial of eritadenine itself was found. Preparation or compound: Fruiting body	¹⁷
Ergothioneine	Biological association	Human lab measure	People get it only from food. A shiitake diet raised plasma ergothioneine for more than 48 hours in 10 men. Preparation or compound: Fruiting body	^{14 15}
Ergosterol (becomes vitamin D2 under UV light)	Biological association	In vitro	Turns into vitamin D2 when exposed to ultraviolet light or sunshine (lab work). No human study of UV-exposed shiitake was found. Preparation or compound: Fruiting body	¹⁵

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 5 lab markers

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

Other5

The evidence

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

Evidence by outcome

Immune markers when shiitake is eaten 2 studies · 52 people in trials Very low certainty Injected lentinan with chemotherapy: gastric cancer (a prescribed medicine) 4 studies Moderate certainty Lentinan with cisplatin chest injection: lung cancer (a prescribed treatment) 2 studies Low certainty Shiitake extracts alongside cancer treatment 2 studies Low certainty Cholesterol and blood fats 4 studies · 120 people in trials Mixed findings Gut bacteria 1 study · 52 people in trials Not enough evidence Well-being scores 1 study · 63 people in trials Very low certainty Exercise recovery and inflammation 1 study Very low certainty Ergothioneine from eating shiitake 2 studies Not enough evidence Injected lentinan in HIV (small 1998 trials) 2 studies · 98 people in trials Not enough evidence Antiviral and antibacterial effects 1 study Not enough evidence

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 19 papers (five systematic reviews or meta-analyses, seven small randomised or controlled trials, one case series, one case report, two product analyses, one animal study and two narrative reviews), plus the Memorial Sloan Kettering and National Cancer Institute pages in full and the GBIF name record. Nutrient values (USDA) come from our earlier summary and were not re-opened. Most papers were read as abstracts, not full text.

Study library: every study we checked 23

Design Research type Year from Search

Study	Design	People	Product, dose, length	Result
Aldwinckle 2020 A Quality-of-Life Study in Healthy Adults Supplemented with Lentinex Beta-Glucan of Shiitake Culinary-Medicinal Mushroom, Lentinus edodes (Agaricomycetes). International Journal of Medicinal Mushrooms · PMID 32749096 · DOI	Controlled trial	63 63 healthy adults	Lentinex (a branded beta-glucan made from shiitake mycelium) versus placebo Mycelium-derived beta-glucan product Not shown here 4 weeks · vs Placebo	The treated group had a statistically significant improvement in well-being compared with placebo. The improvement was bigger in people whose well-being was lower at the start. The abstract gives no scores. Higher self-rated well-being scores than placebo Methods, limits and funding Outcomes: Self-rated well-being questionnaire Limitations: Questionnaire answers, only 4 weeks, one branded product. The abstract names the maker of the tested product (GlycaNova) and the authors' affiliations were not shown in what we read, so we treat the trial as possibly industry-linked. Funding and conflicts: Possibly industry-linked: the abstract describes the maker's own product; funding not stated. Read: abstract
Ampere 2012 Hypersensitivity pneumonitis induced by Shiitake mushroom spores. Medical Mycology · PMID 22329454 · DOI	Case report	1 A 37-year-old man involved in mushroom production	Inhaled shiitake spores at work Spores Not shown here Exposure began in summer 2010; admitted in December 2010	After about a month of cough, breathlessness and weight loss, tests showed lung changes, a high proportion of lymphocytes in lung fluid and antibodies to shiitake spores. All symptoms and scan changes improved once he stopped the exposure. The authors say this was the first European case and that more interest in shiitake may raise the risk for mushroom workers. Lung inflammation from breathing in spores that resolved after exposure stopped Methods, limits and funding Outcomes: Symptoms, lung tests, antibody tests Limitations: One case. Describes a work exposure to spores, not eating shiitake. MSK lists further cases. Funding and conflicts: Not stated in the abstract. Read: abstract
Boels 2022 Shiitake dermatitis: experience of the Poison Control Centre Network in France from 2014 to 2019. Clinical Toxicology · PMID 35404185 · DOI	Case series	125 125 shiitake exposures reported to French poison centres; 59 had dermatitis (ages 19 to 69, median 39)	Raw or undercooked shiitake (Lentinus edodes) eaten Fruiting body Not shown here Rash lasted 1 to 40 days (median 10)	All 59 dermatitis cases followed raw or undercooked shiitake (for example from a wok, in soup, or on pizza). The rash appeared 1 to 168 hours later (median 48 hours) as linear, red, raised itchy streaks on trunk, arms and legs and lasted 1 to 40 days (median 10). More shiitake eaten meant a longer rash (median 4, 7 and 15 days for low, medium and high amounts; P = 0.007). Thirty-eight people had steroids, antihistamines or both, with no demonstrated benefit. Everyone made a complete recovery. The authors say the cause is thought to involve lentinan, a heat-sensitive polysaccharide, and that inadequate cooking seems to drive it. Itchy streaky rash 1 to 168 hours after eating raw or undercooked shiitake; full recovery in all Methods, limits and funding Outcomes: Rash features, timing, duration, treatment, outcome Limitations: A retrospective poison-centre series: it counts calls, not all people who ate shiitake, so it cannot give how common the rash is. Funding and conflicts: Not stated in the abstract. Read: abstract
Dai 2015 Consuming Lentinula edodes (Shiitake) Mushrooms Daily Improves Human Immunity: A Randomized Dietary Intervention in Healthy Young Adults. Journal of the American College of Nutrition · PMID 25866155 · DOI	Controlled trial	52 52 healthy men and women aged 21 to 41	Whole dried shiitake (Lentinula edodes) mushrooms eaten daily Whole dried fruiting body Not shown here 4 weeks · vs Two intake levels compared with each other. There was no placebo or no-mushroom group.	After 4 weeks, immune cells taken from blood grew more in the lab: gamma-delta T cells grew 60% more and NK-T cells about 2-fold more. Saliva secretory IgA rose and C-reactive protein fell. Some cytokines rose (IL-4, IL-10, TNF-alpha, IL-1 alpha) and one fell (MIP-1 alpha); IL-6, IL-1 beta, IL-17 and interferon-gamma did not change. Changes in lab measures of immune cells, saliva antibody and a blood inflammation marker Methods, limits and funding Outcomes: Immune-cell growth and activation (gamma-delta T cells, NK-T cells), saliva secretory IgA, blood C-reactive protein, cytokines Limitations: Healthy young adults, no placebo or untreated comparison group, only 4 weeks. The measures are lab markers: the trial did not count infections or illness. Immune cells were stimulated in the lab, so the result does not show better protection in daily life. Funding and conflicts: Research support from a non-US government source is listed on the record; funding not stated in the abstract. Read: abstract
GBIF 2026 GBIF Backbone Taxonomy: Lentinula edodes (Berk.) Pegler (species key 2537743), checked 2026-10-25 GBIF API · Source	Taxonomy record n/a	n/a	n/a Not shown here	Lentinula edodes (Berk.) Pegler is the accepted name (family Omphalotaceae, order Agaricales). Lentinus edodes (Berk.) Singer, Agaricus edodes Berk., Lentinus shiitake and others are listed as synonyms. Methods, limits and funding Outcomes: Accepted name, family and synonyms Limitations: A database record; it gives names, not health information. Funding and conflicts: Open database Read: full text
Gordon 1998 A placebo-controlled trial of the immune modulator, lentinan, in HIV-positive patients: a phase I/II trial. Journal of Medicine · PMID 10503166	Controlled trial	98 98 HIV-positive people with CD4 counts of 200 to 500 and no current opportunistic infections (two small trials)	Lentinan injected into a vein (a purified shiitake beta-glucan) versus placebo Purified polysaccharide Not shown here 8 to 12 weeks · vs Placebo injection	Side effects were mostly mild, especially when the infusion ran over 30 minutes. With a 10-minute infusion there were nine side effects serious enough to report to the FDA (one case each of anaphylactoid reaction, back pain, leg pain, depression, rigor, fever, chills, granulocytopenia and raised liver enzymes) and four people stopped because of side effects. With the 30-minute infusion there were no reportable side effects. CD4 cells showed a trend upward that was not statistically significant. Among ten people with raised p24, eight on lentinan and two on placebo had falling levels. The authors called these results provocative and needing confirmation. Trend only; not statistically significant Methods, limits and funding Outcomes: Tolerability, CD4 cells, neutrophil activity, p24 levels Limitations: Two small phase I/II trials from 1998. Injection, not eaten shiitake. The authors recommended a longer trial; no result of one is given in the abstract. Funding and conflicts: Not stated in the abstract. Read: abstract
Ina 2013 The use of lentinan for treating gastric cancer. Anti-Cancer Agents in Medicinal Chemistry · PMID 23092289 · DOI	Narrative review review	Review of lentinan in gastric cancer	Lentinan (purified beta-glucan from shiitake) Purified polysaccharide Not shown here	States that lentinan has been approved as a biological response modifier for gastric cancer in Japan, and that recent clinical studies show chemo-immunotherapy with lentinan prolongs survival in advanced gastric cancer compared with chemotherapy alone. Review statement about Japan approval and survival Methods, limits and funding Outcomes: Regulatory status and clinical findings in gastric cancer Limitations: A narrative review, abstract only; the survival statement is the authors' summary of other studies and we did not check them. Funding and conflicts: Not stated in the abstract. Read: abstract
Morales 2021 Modulation of human intestinal microbiota in a clinical trial by consumption of a beta-D-glucan-enriched extract obtained from Lentinula edodes. European Journal of Nutrition · PMID 33580297 · DOI	Controlled trial	52 52 adults aged 18 to 65 with untreated mild high cholesterol	Beta-glucan-enriched extract made from shiitake (Lentinula edodes), mixed into creams, versus placebo creams Extract Not shown here 8 weeks · vs Placebo	After 8 weeks there were no significant differences in lipid or cholesterol measures versus placebo. No change in IL-1 beta, IL-6, TNF-alpha or oxidised LDL. The extract was reported safe. The mix of gut bacteria changed differently from placebo, and some bacteria groups correlated with cholesterol-related markers. The authors say the meaning of the bacterial change is not understood. No cholesterol benefit; gut bacteria composition changed Methods, limits and funding Outcomes: Cholesterol and lipid measures, inflammation markers, gut bacteria Limitations: Small trial; the effect on gut bacteria is a change in a lab measure, not a health benefit. Funding not stated in the abstract. Funding and conflicts: Funding not stated in the abstract. Read: abstract
Nguyen 2017 Clinical features of shiitake dermatitis: a systematic review. International Journal of Dermatology · PMID 28054338 · DOI	Systematic review	50 50 patients from published case reports and case series (38 men, 12 women; mean age 44.6)	Shiitake (Lentinula edodes) eaten Fruiting body Not shown here About 12.5 days without treatment	Most cases followed eating raw mushrooms and 22% followed lightly cooked or undercooked mushrooms. The rash was linear and whip-like ("flagellate") in 98% and itchy in 78%; fever, diarrhoea and mouth or mucosal ulcers also occurred. Tests, skin biopsies and patch or prick tests were nonspecific. The condition cleared by itself in about 12.5 days; treatment may shorten it slightly (to 9 to 11 days). The authors say symptom treatment, reassurance and avoiding re-exposure are enough. Flagellate rash, usually clearing without treatment in about 12 days Methods, limits and funding Outcomes: Clinical features, course and treatment Limitations: Built on published case reports, which are more likely to describe typical or striking cases. Funding and conflicts: Not stated in the abstract. Read: abstract
Risoli 2023 Mushroom-Based Supplements in Italy: Let us Open Pandora's Box. Nutrients · PMID 36771482 · DOI	Product analysis product-analysis	19 19 mushroom food supplements sold in Italy	Powders and extracts labelled as various mushrooms, including Lentinula edodes and Ganoderma lucidum Various Not shown here · vs Label claims	DNA matched the labelled species in only 6 of 19 samples (four Lentinula edodes and two Ganoderma lucidum). The authors say the other results, including the active ingredients measured, were not all in line with what labels indicate. They also say much medicinal-mushroom production is in places without internationally recognised good manufacturing practice. Only 6 of 19 products matched the species on the label Methods, limits and funding Outcomes: DNA match to the species on the label; ergosterol, aflatoxins, heavy metals, nicotine and total glucan Limitations: One country, 19 products, a snapshot. It does not show that all shiitake products are the same. Funding and conflicts: Not stated in the abstract. Read: abstract
Seyfferth 2016 Arsenic, Lead, and Cadmium in U.S. Mushrooms and Substrate in Relation to Dietary Exposure. Environmental Science & Technology · PMID 27484977 · DOI	Product analysis product-analysis	40 40 raw cultivated mushroom samples of 12 types from two US regions, including shiitake	Raw cultivated mushrooms Fruiting body Not shown here · vs Compared types with each other	All samples held less than 1 microgram per gram dry weight of arsenic, lead and cadmium and the authors say overall risk from eating them in the US is low. Cremini had more arsenic than shiitake. Percentages of tolerable intake were higher when calculated for single servings or when the growing material contained more metals. Low metal levels in cultivated US mushrooms including shiitake Methods, limits and funding Outcomes: Total arsenic, lead and cadmium Limitations: Cultivated mushrooms in two US regions only. Wild mushrooms and mushrooms grown on contaminated substrate can contain more. Funding and conflicts: Research support from US government sources is listed on the record. Read: abstract
Sohn 2026 Lentinula edodes in Cancer Treatment: A Systematic Review and Meta-Analysis. Integrative Cancer Therapies · PMID 42648714 · DOI	Meta-analysis	1723 22 trials in 1,723 people with cancer: 13 randomised and 9 controlled non-randomised	Lentinula edodes extracts added to standard cancer treatment (products differ between trials) Extracts (parts differ or not stated in the abstract) Not shown here Varied · vs Standard treatment alone	In the 13 randomised trials, the extract group had a better response rate (odds ratio 1.45, 95% CI 1.01 to 2.07, P = 0.04). Overall survival did not differ (hazard ratio 0.66, 95% CI 0.34 to 1.28). Side effects (blood-related and other) did not differ. Overall quality of life did not differ (standardised mean difference 0.23, 95% CI -0.16 to 0.62). In the 9 non-randomised trials, tumour response and quality of life looked better (P < 0.05). The authors say the results have many limitations and the evidence does not support clear recommendations. Better tumour response, no clear survival or quality-of-life difference (Response OR 1.45 (1.01 to 2.07); survival HR 0.66 (0.34 to 1.28)) Methods, limits and funding Outcomes: Response rate, overall survival, side effects, quality of life Limitations: Abstract only. A mix of products and cancers. The confidence interval for response only just excludes 1. The review itself calls for better trials. Funding and conflicts: Not stated in the abstract. Read: abstract
Spim 2021 Effects of Shiitake Culinary-Medicinal Mushroom, Lentinus edodes (Agaricomycetes), Bars on Lipid and Antioxidant Profiles in Individuals with Borderline High Cholesterol: A Double-Blind Randomized Clinical Trial. International Journal of Medicinal Mushrooms · PMID 34375514 · DOI	Controlled trial	68 68 people with borderline high cholesterol, LDL or triglycerides	Bars made with shiitake (Lentinus edodes) versus placebo bars Not shown here Blood tests at 0, 33 and 66 days · vs Placebo bars	Triglycerides were 10% lower in the shiitake group after 66 days (P = 0.0352). Reduced glutathione (an antioxidant) rose and lipid peroxidation fell. The abstract does not report a change in total cholesterol or LDL. The abstract also says exposure to shiitake triggered dermatitis in 10% of individuals who were sensitive to the mushroom. About 10% lower triglycerides; antioxidant markers improved (P = 0.0352 for triglycerides) Methods, limits and funding Outcomes: Triglycerides, total cholesterol, LDL, HDL, glucose, glutathione, catalase, lipid peroxidation Limitations: Small trial; the abstract names triglycerides only and does not report LDL or total cholesterol changes. Food bars, not a plain mushroom. Funding not stated in the abstract. The authors' conclusion calls it a food that can be an adjuvant; that is stronger than one small trial supports. Funding and conflicts: Funding not stated in the abstract. Read: abstract
Toh 2014 Effect of mushroom diet on pharmacokinetics of gabapentin in healthy Chinese subjects. British Journal of Clinical Pharmacology · PMID 24168107 · DOI	Controlled trial	10 10 healthy men	A diet rich in shiitake mushrooms versus a diet without mushrooms, the day before one dose of the medicine gabapentin Cooked shiitake in a meal (as a diet) Not shown here 1 day, with a washout of at least 7 days between · vs Diet with no mushrooms	The shiitake diet raised plasma ergothioneine for more than 48 hours. Kidney clearance of gabapentin was modestly higher (91.1 versus 76.9 ml/min, P = 0.031), but the amount of gabapentin in the blood (AUC) did not change significantly (P = 0.726). The authors say a diet-drug interaction may occur but may not matter clinically. Plasma ergothioneine up; modest change in gabapentin kidney clearance (P = 0.031 (clearance); P = 0.726 (AUC)) Methods, limits and funding Outcomes: Blood levels of ergothioneine; gabapentin blood levels and kidney clearance Limitations: Ten men, a single day of the diet, a single dose of one medicine. Gabapentin only. Funding and conflicts: Funding not stated in the abstract. Read: abstract
US Department of Agriculture 2025 USDA FoodData Central: shiitake records (SR Legacy 169242, 168436, 168437, 168435; Foundation 1999628), as summarised in our earlier nutrient file FoodData Central · Source	Food composition record n/a	n/a	n/a Not shown here	Per our earlier summary: raw shiitake has about 2.5 g fibre and 304 mg potassium per 100 g; ordinary records show small amounts of vitamin D2; an ergothioneine value of about 11 mg per 100 g fresh in a Foundation record differs about five-fold from a Canadian survey. Methods, limits and funding Outcomes: Nutrient content of shiitake Limitations: We did not re-open the USDA records for this page. It is labelled summary-only. Funding and conflicts: Government database Read: summary-only
Wang 2024 Systematic review and meta-analysis on the efficacy and safety of Injectable Lentinan combined with chemotherapy in the treatment of gastric cancer. Phytomedicine · PMID 38100922 · DOI	Meta-analysis	2729 People with gastric cancer; 31 randomised trials	Injectable lentinan (a purified beta-glucan medicine made from shiitake) added to chemotherapy Purified polysaccharide (not the whole mushroom) Not shown here Varied · vs Chemotherapy alone	Treatment response was better with lentinan plus chemotherapy than with chemotherapy alone (RR 1.48, 95% CI 1.36 to 1.61). Quality of life was better (RR 1.32, 95% CI 1.20 to 1.45). CD3+, CD4+, CD4+/CD8+ and NK cells rose and CD8+ fell. There was less white blood cell decline, fewer gastrointestinal reactions and less platelet decline. The authors saw no serious adverse effects and graded the evidence for these outcomes as high or moderate (GRADE). Better response rate and quality-of-life scores when the injection was added to chemotherapy (Efficacy RR 1.48 (1.36 to 1.61); quality of life RR 1.32 (1.20 to 1.45)) Methods, limits and funding Outcomes: Treatment efficacy, immune-cell measures, quality of life, side effects Limitations: Only the abstract was read, so we could not check the quality of the 31 trials ourselves. The authors say more trials are needed. This is a prescribed injection given by a care team: it says nothing about eating shiitake or taking capsules. Funding and conflicts: Not stated in the abstract. Read: abstract
Yang 2013 Lentinus edodes promotes fat removal in hypercholesterolemic mice. Experimental and Therapeutic Medicine · PMID 24255670 · DOI	Animal study animal	Mice fed a high-fat diet	Shiitake (5, 10 or 20% of the diet) or the compound eritadenine Whole mushroom diet or isolated compound Not shown here 4 weeks · vs High-fat diet alone	In mice, total cholesterol, LDL and triglycerides fell in a dose-dependent way with shiitake. Activity of the CYP7A1 gene in the liver went up, liver fat fell and artery plaque formation was reduced. The authors conclude shiitake may help regulate lipid metabolism in mice. Lower blood fats in mice Methods, limits and funding Outcomes: Blood cholesterol, LDL, triglycerides, liver gene activity, plaque Limitations: Animal study. It does not show that shiitake lowers cholesterol in people; MSK says there is no clinical proof of this in people. Funding and conflicts: Not stated in the abstract. Read: abstract
Zembron-Lacny 2013 Effect of shiitake (Lentinus edodes) extract on antioxidant and inflammatory response to prolonged eccentric exercise. Journal of Physiology and Pharmacology · PMID 23756400	Controlled trial	Healthy men (number not stated in the abstract)	Shiitake extract versus placebo, in a crossover design, before two exercise sessions Extract Not shown here 10 days before each exercise trial · vs Placebo	The extract had no effect on immune cell numbers or inflammatory mediators, with the exception of IL-10. Thiol redox status and nitric oxide rose after the extract, while H2O2 and 8-isoprostanes did not change. The authors conclude no effect on inflammation markers but an antioxidant action through nitric oxide and thiol status. No effect on inflammation markers; some antioxidant markers changed Methods, limits and funding Outcomes: Muscle damage, blood cells, inflammation and antioxidant markers after a long run with a downhill phase Limitations: Small crossover study in healthy men; lab markers only. Number of participants not given in the abstract. Funding and conflicts: Research support from a non-US source is listed on the record. Read: abstract
Zhang 2019 Mushroom polysaccharide lentinan for treating different types of cancers: A review of 12 years clinical studies in China. Progress in Molecular Biology and Translational Science · PMID 31030752 · DOI	Systematic review	9474 About 9,474 reported cancer cases from 135 studies published in China, 2004 to 2016 (lung, gastric and colorectal cancer most common)	Lentinan (purified polysaccharide from Lentinula edodes) used with chemotherapy or radiotherapy Purified polysaccharide Not shown here Varied · vs Varied	The authors concluded that overall clinical data show a solid effect on quality of life and on promoting the effect of chemotherapy and radiotherapy. They note that lentinan has been approved as an add-on cancer medicine in China and Japan since the 1980s. Authors report improved quality of life and added benefit alongside standard treatment Methods, limits and funding Outcomes: Quality of life and effect on the benefit of chemotherapy and radiation Limitations: Only the abstract was read. The studies were mostly Chinese-language reports of mixed design; the abstract does not give effect sizes or study quality. Counting cases from many small reports does not replace well-controlled trials. Funding and conflicts: Research support from a non-US government source is listed on the record. Read: abstract
Zhao 2021 Lentinan combined with cisplatin for the treatment of non-small cell lung cancer. Medicine · PMID 33761711 · DOI	Systematic review	1390 People with non-small cell lung cancer; 17 randomised trials	Lentinan injected into the chest (thoracic injection) together with cisplatin Purified polysaccharide Not shown here Varied · vs Cisplatin chest injection alone	Clinical efficacy was higher with lentinan plus cisplatin (RR 1.34, 95% CI 1.21 to 1.48) and quality of life was higher (RR 1.48, 95% CI 1.27 to 1.72). The group with lentinan had fewer gastrointestinal reactions and less bone marrow suppression. The authors say the trials had low methodological quality and a high risk of bias. Higher response and quality-of-life scores, in trials the authors rate as low quality (Efficacy RR 1.34 (1.21 to 1.48); quality of life RR 1.48 (1.27 to 1.72)) Methods, limits and funding Outcomes: Clinical efficacy, quality of life, adverse reactions Limitations: The authors themselves point to low methodological quality and high risk of bias. Abstract only. Chest injection with cisplatin is a hospital treatment and has nothing to do with eating shiitake. Funding and conflicts: Not stated in the abstract. Read: abstract
Zhou 2024 Lentinan progress in inflammatory diseases and tumor diseases. European Journal of Medical Research · PMID 38172925 · DOI	Narrative review review	Review of lentinan research in inflammatory diseases and cancer	Lentinan (purified beta-glucan from shiitake) Purified polysaccharide Not shown here	States that lentinan has been approved as an add-on to chemotherapy in China and Japan, and that clinical experiments are reported to show benefit with chemotherapy in lung, colorectal and gastric cancer. Much of what it describes is lab and mechanism work. Review statement about approvals; mostly mechanism work Methods, limits and funding Outcomes: Mechanisms and clinical research Limitations: A narrative review, abstract only. Not a systematic analysis of trials. Funding and conflicts: Not stated in the abstract. Read: abstract
n/a 2024 National Cancer Institute (NCI): Medicinal Mushrooms (PDQ), Health Professional Version (summary updated 6 Nov 2024; page read 2026-10-25) n/a · Source	Authoritative guidance n/a	n/a	n/a Not shown here	Says the FDA has not approved the use of medicinal mushrooms as a treatment for cancer or any other medical condition. Says dietary supplements are not formally reviewed for manufacturing consistency every year, so ingredients may vary considerably from lot to lot and there is no guarantee that label ingredients are present in the stated amounts. Lists Lentinus edodes (shiitake) among the medicinal mushrooms covered; the page we read says little else specific to shiitake. Methods, limits and funding Outcomes: Regulatory status and supplement quality Limitations: A general summary for health professionals; it covers medicinal mushrooms as a group and says little about shiitake itself. Funding and conflicts: Independent public information source Read: full text
n/a 2026 Memorial Sloan Kettering Cancer Center: Shiitake Mushroom (About Herbs, page read 2026-10-25) n/a · Source	Authoritative guidance n/a	n/a	n/a Not shown here	Says small studies of shiitake extract have mixed results and that most lentinan studies used injections, so it is uncertain whether eating shiitake gives similar effects. Says one clinical trial showed a shiitake extract was not effective for prostate cancer. Says compounds in shiitake lower cholesterol in lab studies but there is no proof from clinical trials in people. Lists side effects: skin inflammation, more sensitivity to sunlight, a raised level of certain white blood cells, upset stomach, pneumonia from hypersensitivity to spores, and small bowel obstruction from eating a whole mushroom. Case reports include flagellate dermatitis after raw or even cooked shiitake, and esophageal symptoms linked to food allergy. Lab interaction listed: chronic eating may raise eosinophil count. No herb-drug interaction section was found on the page. Methods, limits and funding Outcomes: Purported uses, side effects and case reports, lab interactions Limitations: Summary for patients and clinicians; secondary source for the cases and trials it cites. The page does not show an update date in the text we read. Funding and conflicts: Independent hospital information source Read: full text

What we do not know yet

No trial shows that eating shiitake or taking supplements prevents infections or cancer; the immune results are lab markers.
Almost all the cancer evidence is for the purified lentinan injection, not the mushroom or capsules.
How common shiitake dermatitis is among people who eat shiitake is unknown, and cases have been reported after cooked mushroom.
No studies of shiitake supplements in pregnancy, breastfeeding or children, and only one drug interaction (gabapentin) has been tested.
Cholesterol results conflict between two small trials with different products.

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. Newer evidence can change the ratings.

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".

Metabolic 1

●

Blood triglycerides

Lowered (bars); not studied or unchanged elsewhere in trials

A type of fat in the blood. High levels are linked to heart and blood vessel disease risk.

Low certainty

Results and what it means

Why it was measured

A standard blood fat test.

Statistical vs. clinical meaning

Statistically significant in one small placebo-controlled trial.

Safety implication

Dermatitis was reported in people sensitive to the mushroom.

Study	Result	People	Product
¹³	About 10% lower in the shiitake-bar group after 66 days (P = 0.0352).	68 people with borderline high cholesterol, LDL or triglycerides	Shiitake bars versus placebo bars

¹³

Other 8

▲

Immune-cell growth in the lab (gamma-delta T and NK-T cells)

Raised in trials

Blood cells taken from a person are stimulated in the lab and counted again. It shows how readily some immune cells multiply, not whether the person is protected from infection.

Very low certainty

Results and what it means

Why it was measured

Used in nutrition trials as a stand-in for immune readiness.

Statistical vs. clinical meaning

Large changes in a lab test, but from one trial with no comparison group.

Safety implication

A higher value does not show better protection.

Study	Result	People	Product
⁴	Gamma-delta T cells grew 60% more and NK-T cells about 2-fold more after 4 weeks of eating dried shiitake.	52 healthy adults aged 21 to 41	Whole dried shiitake eaten daily, two intake levels

⁴

●

Saliva secretory IgA and blood C-reactive protein

Raised (IgA) and lowered (CRP) in trials

Secretory IgA is an antibody found in saliva and on the gut lining. C-reactive protein (CRP) is a blood marker that rises with inflammation.

Very low certainty

Results and what it means

Why it was measured

Used as simple markers of gut immunity (IgA) and general inflammation (CRP).

Statistical vs. clinical meaning

Direction of change reported in the abstract; no placebo group.

Safety implication

None noted; shiitake can cause rash if eaten raw.

Study	Result	People	Product
⁴	Saliva secretory IgA rose and CRP fell after 4 weeks of eating dried shiitake. The abstract gives no figures for these two.	52 healthy adults	Whole dried shiitake eaten daily

⁴

▲

Tumour response rate with add-on shiitake products

Raised in trials

The share of people whose tumours shrink or are controlled during treatment, as judged by the trial.

Low certainty

Results and what it means

Why it was measured

A common cancer-trial outcome. It is not the same as living longer.

Statistical vs. clinical meaning

Statistically significant in both reviews. The injection result is the stronger of the two; the extract result only just excludes no effect and did not carry over to survival.

Safety implication

Cancer treatment decisions belong with the care team.

Study	Result	People	Product
¹⁶	Injected lentinan plus chemotherapy: efficacy RR 1.48 (95% CI 1.36 to 1.61) versus chemotherapy alone.	People with gastric cancer (31 trials)	Injectable lentinan
¹²	Shiitake extracts plus standard treatment: response odds ratio 1.45 (1.01 to 2.07) in randomised trials; survival no clear difference.	People with various cancers (13 randomised trials)	Shiitake extracts

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CD3+, CD4+, CD4+/CD8+ and NK cells with injected lentinan

Raised (CD8+ lowered) in trials

Counts or shares of T cells and natural killer (NK) cells in blood. They describe how the immune system is set up, not whether someone is protected.

Moderate certainty

Results and what it means

Why it was measured

Used in cancer trials to see whether treatment is weakening or supporting immune cells.

Statistical vs. clinical meaning

Reported by the authors as significant, with high or moderate GRADE.

Safety implication

Not a measure of protection from infection.

Study	Result	People	Product
¹⁶	CD3+, CD4+, CD4+/CD8+ and NK cells rose and CD8+ fell with injected lentinan plus chemotherapy compared with chemotherapy alone. The abstract gives no figures for these.	People with gastric cancer	Injectable lentinan with chemotherapy

¹⁶

●

Total cholesterol and LDL cholesterol

Unchanged in trials

Blood fats measured in standard cholesterol tests. LDL is the type linked most closely to artery disease.

Low certainty

Results and what it means

Why it was measured

Standard heart-risk tests.

Statistical vs. clinical meaning

A null result in one small trial. This is evidence against a cholesterol-lowering effect for this extract.

Safety implication

Reported safe in this trial.

Study	Result	People	Product
⁸	No significant difference in lipid or cholesterol measures versus placebo after 8 weeks.	52 adults with mild high cholesterol	Shiitake beta-glucan-enriched extract versus placebo

⁸

▲

Antioxidant markers (glutathione, thiol status)

Raised in trials

Blood measures of the body's antioxidant systems. They show chemistry, not health.

Very low certainty

Results and what it means

Why it was measured

Used to test whether a food changes oxidative stress.

Statistical vs. clinical meaning

Lab markers in two small studies.

Safety implication

None reported.

Study	Result	People	Product
¹³	Reduced glutathione rose and lipid peroxidation fell with shiitake bars.	68 people with borderline high cholesterol	Shiitake bars
¹⁸	Thiol redox status and nitric oxide rose with shiitake extract; H2O2 and 8-isoprostanes did not change.	Healthy men around hard exercise	Shiitake extract

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▲

Blood ergothioneine

Raised in trials

The level of ergothioneine, an antioxidant amino acid that comes only from food, in blood plasma.

Low certainty

Results and what it means

Why it was measured

Shows how much of the compound is absorbed from a meal.

Statistical vs. clinical meaning

Clear rise in a small study; the health meaning is not known.

Safety implication

May change gabapentin kidney clearance modestly (see Safety tab).

Study	Result	People	Product
¹⁴	Plasma ergothioneine rose for more than 48 hours after a diet rich in shiitake.	10 healthy men	Shiitake-rich diet

¹⁴

▲

Self-rated well-being score

Raised in trials

A questionnaire in which people rate how well they feel.

Very low certainty

Results and what it means

Why it was measured

Measures how people feel, but is easily affected by expectation.

Statistical vs. clinical meaning

Statistically significant in one short, possibly industry-linked trial.

Safety implication

None reported in the abstract.

Study	Result	People	Product
¹	Higher well-being than placebo after 4 weeks, with larger gains when starting scores were lower. No scores in the abstract.	63 healthy adults	Branded shiitake mycelium beta-glucan versus placebo

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 5

Raw or undercooked shiitake can cause shiitake dermatitis, an itchy rash in whip-like streaks. Shiitake dermatitis (also called flagellate dermatitis) is a rash of linear, red, itchy, raised streaks on the trunk, arms and legs. In a French poison-centre series, 59 of 125 shiitake exposures led to dermatitis. All followed raw or undercooked shiitake (for example from a wok, in soup or on pizza). The rash appeared a median of 48 hours later (anywhere from 1 hour to 7 days) and lasted a median of 10 days (1 to 40). The more that was eaten, the longer it lasted. Steroids and antihistamines showed no clear benefit and everyone recovered. A review of 50 published cases found 98% had the streaky pattern, 78% itch, and some had fever, diarrhoea or mouth ulcers; most cases followed raw mushrooms and 22% followed lightly cooked ones. MSK also lists cases after cooked shiitake. So cooking thoroughly lowers the risk but the sources do not promise it removes it. Case series ^{3 9 23}
Do not eat shiitake raw. The French authors say the cause is thought to involve lentinan, a heat-sensitive sugar in the cell walls, and that inadequate cooking seems to drive the rash. Raw shiitake (for example in a salad or a smoothie) and lightly cooked shiitake are the usual stories in the case reports. This is a skin reaction, not a food-poisoning illness, and it has a good prognosis, but it can last weeks and be very itchy. Someone who has had it should avoid re-exposure. Case series ^{3 9}
Lentinan injection is a separate prescribed medicine with its own reactions. Lentinan given into a vein or into the chest by a care team is not the same as eating shiitake or taking a supplement. In two small 1998 trials in people with HIV, a 10-minute infusion caused nine reactions serious enough to report to the FDA (one each of anaphylactoid reaction, back pain, leg pain, depression, rigor, fever, chills, granulocytopenia and raised liver enzymes), and a 30-minute infusion caused none. In the 31-trial gastric cancer analysis the authors saw no serious adverse effects and fewer white blood cell and platelet drops than with chemotherapy alone. Because it is given by clinicians, none of this applies to home use. Controlled trial ^{6 16}
Breathing in spores, a lung reaction for mushroom workers. A 37-year-old mushroom worker developed hypersensitivity pneumonitis (lung inflammation caused by an allergy-type reaction) from inhaled shiitake spores and recovered after stopping the exposure. MSK lists a second case in a lung cancer patient. People who grow shiitake at home or work with large amounts should take breathlessness or a long-lasting cough seriously. Case report ^{2 23}
Swallowing a whole shiitake has blocked the bowel. MSK lists small bowel obstruction from eating a whole shiitake mushroom, including a case that needed surgery. Frequency is unknown. Case report ²³

Side effects 8

Effect	How often	Severity and recovery	Evidence
Shiitake dermatitis (flagellate rash) Linked to raw or undercooked mushrooms; MSK also lists cooked cases.	59 of 125 shiitake exposures reported to French poison centres (2014 to 2019). These were calls to poison centres, so this is not a rate for people who eat shiitake.	moderate (very itchy, can last weeks) Cleared in all patients, median 10 days (1 to 40)	Case series ^{3 9}
Dermatitis in people already sensitive to the mushroom (trial of shiitake bars) Shows the skin reaction can also happen in a trial of a shiitake food product.	The abstract says dermatitis occurred in 10% of individuals who were sensitive to the mushroom	unknown Not described in the abstract	Controlled trial ¹³
Fever, diarrhoea or mouth ulcers with the rash	Reported in some of the 50 reviewed cases; figures not in the abstract	mild to moderate Self-limiting in the review	Systematic review ⁹
Sun sensitivity, higher eosinophil count and stomach upset after prolonged use of shiitake powder MSK lists these under side effects and case reports; it also says chronic eating may raise the eosinophil count.	Case reports; frequency unknown	unknown Not described	Authoritative guidance ²³
Esophageal symptoms linked to a food allergy Mushroom allergy exists; any food allergy can cause serious reactions.	One reported case (a 37-year-old man)	unknown Not described	Authoritative guidance ²³
Lung inflammation from inhaled spores (hypersensitivity pneumonitis) Exposure to spores at work, not from eating.	Case reports (mushroom workers)	moderate to serious Improved after exposure stopped in the case we read	Case report ^{2 23}
Small bowel blockage from swallowing a whole mushroom Whole mushroom swallowed, not chewed.	Case reports; frequency unknown	serious (surgery in some cases) Resolved after surgery or bowel rest in the cases listed	Authoritative guidance ²³
Reactions to the lentinan injection (anaphylactoid reaction, rigor, fever, chills, back and leg pain, depression, granulocytopenia, raised liver enzymes) Injection, given by clinicians only. Not related to eating shiitake.	Nine serious reportable reactions among the people on a 10-minute infusion in one small trial; none with a 30-minute infusion	moderate to serious The authors say all were relieved within 24 hours	Controlled trial ⁶

Liver

In the sources we read, no case of liver injury was linked to eating shiitake or taking shiitake supplements. One trial of lentinan by injection in people with HIV listed a raised liver enzyme level as one of nine serious reactions. We could not read LiverTox or other agency records for shiitake, so this is an absence of reports in what we read, not proof of safety. ^{6 23}

How often. No rate could be found.

Monitoring. No agency monitoring advice was read. Anyone with liver disease should ask a doctor or pharmacist before taking shiitake supplements. Yellow skin or eyes, dark urine or pale stools after any supplement need medical advice.

p10503166.

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

Medicines and supplements 6

With	Why it matters	Importance	Evidence	What to do
Gabapentin prescription	Ergothioneine from shiitake may stimulate a kidney transporter (OCTN1) that clears gabapentin (lab work cited by the authors).	In 10 healthy men, a shiitake-rich diet modestly raised kidney clearance of gabapentin (91.1 versus 76.9 ml/min, P = 0.031) but did not significantly change the amount of gabapentin in the blood (P = 0.726). The authors say it may not be clinically important.	Controlled trial Low certainty ¹⁴	Tell your prescriber or pharmacist if you eat a lot of shiitake and take gabapentin.
Chemotherapy, radiotherapy and other cancer treatment prescription	Injected lentinan and some shiitake extracts have been given together with chemotherapy in trials; reviews did not find more side effects with the extracts (Sohn 2026) and fewer blood-count drops with the injection (Wang 2024).	These were supervised trials of specific products. They do not show that any shiitake supplement is safe with a particular cancer drug.	Systematic review Low certainty ^{12 16 23}	People having cancer treatment should tell the oncology team and pharmacist about any shiitake product before using it.
Immune-suppressing medicines (for example after a transplant or for autoimmune disease) prescription	Shiitake beta-glucans act on immune cells in the lab and changed immune markers in one human study.	No source we read describes an interaction. This is a theoretical concern only, so we cannot say whether it matters.	Theoretical Not enough evidence ⁴	Ask the prescriber before using shiitake extracts or powders.
Blood thinners (warfarin-type) and antiplatelet medicines prescription		MSK's page has no herb-drug interaction listing for shiitake and we found no report of a bleeding interaction. Absence of reports is not proof of safety.	None found Not enough evidence ²³	Ask a pharmacist before taking shiitake supplements with blood thinners.
Blood tests (eosinophil count) lab test	MSK says chronic consumption of shiitake may increase the eosinophil count, a white blood cell.	A raised eosinophil count can cause confusion in blood tests. Cause is a case-report level source.	Authoritative guidance Low certainty ²³	Tell the clinician who orders blood tests if you take shiitake regularly.
Medicines that increase sun sensitivity prescription	MSK lists increased skin sensitivity to sunlight among shiitake side effects after prolonged shiitake powder use.	No source describes a combined effect. Mentioned only because both can affect the skin in sunlight.	Theoretical Not enough evidence ²³	Use sun protection if a rash or sun sensitivity appears and ask a clinician.

Who should check first 6

Situation	Advice	Evidence
A past episode of shiitake dermatitis, or an allergy to mushrooms	Avoid shiitake. The review of 50 cases recommends avoiding re-exposure.	Systematic review ^{9 23}
Pregnancy and breastfeeding	No source we read addresses shiitake supplements in pregnancy or breastfeeding. Cooked shiitake as part of an ordinary meal is a different matter from supplements, but ask a doctor, midwife or pharmacist about supplements, powders and extracts.	No data ²³
Children	No source we read tested shiitake supplements in children. Whole mushrooms can cause a bowel blockage if swallowed whole, and small children should not be given whole pieces.	No data ²³
People who grow shiitake or work around large amounts of spores	Ask a doctor about a long-lasting cough or breathlessness. Hypersensitivity pneumonitis has been reported.	Case report ^{2 23}
Taking immune-suppressing medicines, having cancer treatment, or having surgery planned	Ask the prescriber or care team before using shiitake extracts or powders. No source we read describes a specific problem, but the research on these products is limited.	No data ^{23 12}
Kidney disease or liver disease	No source we read addresses kidney or liver disease with shiitake. Ask a doctor before using shiitake supplements.	No data ²³

Overdose, product quality and regulators

Summary. Shiitake is a widely eaten food. The harms documented in the sources we read are the dermatitis after raw or undercooked mushroom, spore-related lung inflammation in workers, rare bowel blockage from swallowing a whole mushroom, and reactions to the lentinan injection. Poisoning by shiitake in the usual sense (like a poisonous wild mushroom) was not described.

Animal. Not reviewed in depth. MSK refers to lab and animal findings on many properties but gives no toxicity figures.

Human doses studied. Trials ran from 10 days to about 66 days and used different products. This page does not give amounts, and none are advised.

High dose or long term signals. In the French series, a larger amount of raw or undercooked shiitake went with a longer rash. MSK says chronic consumption may raise the eosinophil count. Long-term safety of supplements is not known.

Overdose response. No overdose description was found. For a spreading rash, trouble breathing or swelling after eating shiitake, get medical help. Poison centres in France handle shiitake dermatitis calls.

Genotoxicity. Not found in the sources we read.

Toxic or hazardous parts. The cultivated fruiting body is a common food. Spores can cause lung reactions in workers. Wild fungi that look similar are not covered in the sources we read; do not pick wild mushrooms without expert identification.

Mushroom supplements are not held to the rules for approved medicines. NCI says ingredients may vary a lot from lot to lot and label amounts are not guaranteed. A 2023 Italian analysis of 19 mushroom supplements matched the labelled species in only 6.

Species and label accuracy. DNA matched the labelled species in only 6 of 19 mushroom supplements sold in Italy (four were Lentinula edodes). The authors also found that some measured contents did not match what labels indicate. This is one country and a small sample. ¹⁰

Label amounts and batch differences. NCI says supplement ingredients may vary considerably from lot to lot and there is no guarantee that label ingredients are present in the stated amounts. ²²

Fruiting body versus mycelium on grain. Our nutrient summary notes that mycelium grown on grain carries leftover grain starch and can differ from the fruiting body. We did not re-open the source for shiitake specifically. NCI makes a similar point for reishi products, not for shiitake. ²²

Heavy metals in cultivated mushrooms. In 40 raw cultivated US mushrooms (including shiitake), arsenic, lead and cadmium were all under 1 microgram per gram dry weight, and the authors call the overall risk low. Higher percentages of tolerable intake appeared when growing material contained more metals. ¹¹

Wild mushrooms. Wild mushrooms can absorb high quantities of metals, say the authors of the US survey. Do not pick wild mushrooms without expert identification. ¹¹

Body	Action	Date
US National Cancer Institute (PDQ) (United States)	States that the FDA has not approved the use of medicinal mushrooms as a treatment for cancer or any other medical condition. Notes that supplements are not formally reviewed for manufacturing consistency every year and that label ingredients are not guaranteed. source	2024-11-06
Japan and China (lentinan injection) (Japan; China)	Lentinan, a purified polysaccharide from shiitake, is approved as an add-on to chemotherapy (in Japan, for gastric cancer). It is a prescription injection and is a different thing from shiitake food, powder or extract. source	n/a

When to get medical help

Trouble breathing, swelling of the face or lips, hives or feeling faint after eating shiitake or a mushroom supplement: call emergency services.
A spreading, very itchy streaky rash with fever, mouth ulcers or diarrhoea after eating shiitake: get medical advice.
A cough or breathlessness that lasts after working with mushroom growing or spores: see a doctor.
Severe belly pain, repeated vomiting or a swollen belly after swallowing a whole mushroom: get urgent medical help (bowel blockage has been reported).
Yellow skin or eyes, dark urine or pale stools after any supplement: stop it and get medical help.

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 shiitake?

Shiitake (Lentinula edodes) is a mushroom, a fungus rather than a plant. It is a common food in East Asia and worldwide and is also sold as powders and extracts. Lentinan, a purified sugar-like substance from shiitake, is used as an injected medicine in Japan and China.

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Is shiitake safe to eat?

Cooked shiitake is an ordinary food. The main documented harm is a rash after eating it raw or undercooked, and MSK lists a few cases after cooked mushroom too. Other reports are rare: lung inflammation in mushroom workers who breathe in spores, and bowel blockage from swallowing a whole mushroom.

^{3 9 23}

What is shiitake dermatitis?

It is an itchy rash of red, raised, whip-like streaks, also called flagellate dermatitis. In a French poison-centre series of 59 cases, it appeared a median of 48 hours after raw or undercooked shiitake, lasted a median of 10 days, and every patient recovered. A review of 50 published cases found fever, diarrhoea or mouth ulcers in some people.

^{3 9}

Can I eat shiitake raw?

It is best not to. Raw and undercooked shiitake caused the rash in the French cases, and the authors say inadequate cooking seems to drive it. The rash can be very itchy and last weeks, though it is not described as dangerous. MSK says cases have also happened after cooked shiitake.

^{3 9 23}

Does shiitake boost the immune system?

In one small study, healthy adults who ate dried shiitake for 4 weeks showed changes in some immune-cell lab tests and a saliva antibody. There was no comparison group and nobody counted infections, so it does not show that shiitake prevents illness.

^{4 23}

What is lentinan, and is it the same as shiitake?

No. Lentinan is a purified beta-glucan taken out of shiitake and given as an injection by a care team, alongside chemotherapy, in Japan and China. Eating shiitake, or taking powder or extract capsules, is not the same. MSK says most lentinan studies used injections and that it is uncertain whether eating shiitake has similar effects.

^{16 7 21 23}

Does shiitake help against cancer?

Shiitake is not a cancer treatment. Injected lentinan added to chemotherapy was linked to better response and quality of life in a pooled analysis of 31 gastric cancer trials. For shiitake extracts, a 2026 review found a better response rate but no clear difference in survival, and said the evidence does not support firm recommendations.

^{16 12 23}

Does shiitake lower cholesterol?

It did in mice. In people the results are mixed: shiitake bars lowered triglycerides about 10% in one small trial, but a shiitake beta-glucan extract did not change cholesterol in another. MSK says there is no clinical proof in people.

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Does shiitake interact with medicines?

The sources we read show only one tested interaction: a shiitake-rich diet modestly raised kidney clearance of gabapentin, probably not important. MSK says chronic eating may raise the eosinophil count in blood tests. Cancer patients and people on immune-suppressing medicines should tell their team or pharmacist about any shiitake product.

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Is shiitake safe in pregnancy, breastfeeding or for children?

The sources we read do not address shiitake supplements in pregnancy, breastfeeding or children. Cooked shiitake in an ordinary meal is a different matter from powders and extracts, so ask a doctor, midwife or pharmacist about supplements. Young children should not be given whole pieces because of the bowel-blockage risk.

²³

How do shiitake supplements differ from the mushroom?

Supplements can be fruiting-body powder, hot-water or dual extracts, or mycelium grown on grain, and they can differ a lot from the cooked mushroom. NCI says supplement ingredients may vary from lot to lot and label amounts are not guaranteed. In a 2023 Italian analysis of 19 mushroom supplements, only 6 matched the species on the label.

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Does shiitake contain vitamin D?

Ordinary shiitake contains little, but it holds ergosterol, which turns into vitamin D2 when exposed to ultraviolet light. Our nutrient summary says ordinary USDA records show small amounts. We did not find a human study of UV-exposed shiitake, so we cannot say it is a reliable source.

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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 19 papers (five systematic reviews or meta-analyses, seven small randomised or controlled trials, one case series, one case report, two product analyses, one animal study and two narrative reviews), plus the Memorial Sloan Kettering and National Cancer Institute pages in full and the GBIF name record. Nutrient values (USDA) come from our earlier summary and were not re-opened. Most papers were read as abstracts, not full text.
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 shiitake.

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.

Aldwinckle J, Kristiansen B. A Quality-of-Life Study in Healthy Adults Supplemented with Lentinex Beta-Glucan of Shiitake Culinary-Medicinal Mushroom, Lentinus edodes (Agaricomycetes).. International Journal of Medicinal Mushrooms. 2020. PMID 32749096. DOI 10.1615/IntJMedMushrooms.2020034208. (abstract)
Ampere A, Delhaes L, Soots J, et al. Hypersensitivity pneumonitis induced by Shiitake mushroom spores.. Medical Mycology. 2012. PMID 22329454. DOI 10.3109/13693786.2012.658091. (abstract)
Boels D, Greillet C, Langrand J, et al. Shiitake dermatitis: experience of the Poison Control Centre Network in France from 2014 to 2019.. Clinical Toxicology. 2022. PMID 35404185. DOI 10.1080/15563650.2022.2059496. (abstract)
Dai X, Stanilka JM, Rowe CA, et al. Consuming Lentinula edodes (Shiitake) Mushrooms Daily Improves Human Immunity: A Randomized Dietary Intervention in Healthy Young Adults.. Journal of the American College of Nutrition. 2015. PMID 25866155. DOI 10.1080/07315724.2014.950391. (abstract)
GBIF. GBIF Backbone Taxonomy: Lentinula edodes (Berk.) Pegler (species key 2537743), checked 2026-10-25. GBIF API. 2026. (full text)
Gordon M, Bihari B, Goosby E, et al. A placebo-controlled trial of the immune modulator, lentinan, in HIV-positive patients: a phase I/II trial.. Journal of Medicine. 1998. PMID 10503166. (abstract)
Ina K, Kataoka T, Ando T. The use of lentinan for treating gastric cancer.. Anti-Cancer Agents in Medicinal Chemistry. 2013. PMID 23092289. DOI 10.2174/1871520611313050002. (abstract)
Morales D, Shetty SA, Lopez-Plaza B, et al. Modulation of human intestinal microbiota in a clinical trial by consumption of a beta-D-glucan-enriched extract obtained from Lentinula edodes.. European Journal of Nutrition. 2021. PMID 33580297. DOI 10.1007/s00394-021-02504-4. (abstract)
Nguyen AH, Gonzaga MI, Lim VM, et al. Clinical features of shiitake dermatitis: a systematic review.. International Journal of Dermatology. 2017. PMID 28054338. DOI 10.1111/ijd.13433. (abstract)
Risoli S, Nali C, Sarrocco S, et al. Mushroom-Based Supplements in Italy: Let us Open Pandora's Box.. Nutrients. 2023. PMID 36771482. DOI 10.3390/nu15030776. (abstract)
Seyfferth AL, McClatchy C, Paukett M. Arsenic, Lead, and Cadmium in U.S. Mushrooms and Substrate in Relation to Dietary Exposure.. Environmental Science & Technology. 2016. PMID 27484977. DOI 10.1021/acs.est.6b02133. (abstract)
Sohn BS, Choi IS, Kim SY, et al. Lentinula edodes in Cancer Treatment: A Systematic Review and Meta-Analysis.. Integrative Cancer Therapies. 2026. PMID 42648714. DOI 10.1177/15347354261483632. (abstract)
Spim SRV, Pistila AMH, Pickler TB, et al. Effects of Shiitake Culinary-Medicinal Mushroom, Lentinus edodes (Agaricomycetes), Bars on Lipid and Antioxidant Profiles in Individuals with Borderline High Cholesterol: A Double-Blind Randomized Clinical Trial.. International Journal of Medicinal Mushrooms. 2021. PMID 34375514. DOI 10.1615/IntJMedMushrooms.2021038773. (abstract)
Toh DS, Limenta LM, Yee JY, et al. Effect of mushroom diet on pharmacokinetics of gabapentin in healthy Chinese subjects.. British Journal of Clinical Pharmacology. 2014. PMID 24168107. DOI 10.1111/bcp.12273. (abstract)
US Department of Agriculture. USDA FoodData Central: shiitake records (SR Legacy 169242, 168436, 168437, 168435; Foundation 1999628), as summarised in our earlier nutrient file. FoodData Central. 2025. (summary-only)
Wang Y, Wang H, Chai K, et al. Systematic review and meta-analysis on the efficacy and safety of Injectable Lentinan combined with chemotherapy in the treatment of gastric cancer.. Phytomedicine. 2024. PMID 38100922. DOI 10.1016/j.phymed.2023.155242. (abstract)
Yang H, Hwang I, Kim S, et al. Lentinus edodes promotes fat removal in hypercholesterolemic mice.. Experimental and Therapeutic Medicine. 2013. PMID 24255670. DOI 10.3892/etm.2013.1333. (abstract)
Zembron-Lacny A, Gajewski M, Naczk M, et al. Effect of shiitake (Lentinus edodes) extract on antioxidant and inflammatory response to prolonged eccentric exercise.. Journal of Physiology and Pharmacology. 2013. PMID 23756400. (abstract)
Zhang M, Zhang Y, Zhang L, et al. Mushroom polysaccharide lentinan for treating different types of cancers: A review of 12 years clinical studies in China.. Progress in Molecular Biology and Translational Science. 2019. PMID 31030752. DOI 10.1016/bs.pmbts.2019.02.013. (abstract)
Zhao C, Yan H, Pang W, et al. Lentinan combined with cisplatin for the treatment of non-small cell lung cancer.. Medicine. 2021. PMID 33761711. DOI 10.1097/MD.0000000000025220. (abstract)
Zhou G, Liu H, Yuan Y, et al. Lentinan progress in inflammatory diseases and tumor diseases.. European Journal of Medical Research. 2024. PMID 38172925. DOI 10.1186/s40001-023-01585-7. (abstract)
n/a. National Cancer Institute (NCI): Medicinal Mushrooms (PDQ), Health Professional Version (summary updated 6 Nov 2024; page read 2026-10-25). n/a. 2024. (full text)
n/a. Memorial Sloan Kettering Cancer Center: Shiitake Mushroom (About Herbs, page read 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.