Shiitake (Lentinula edodes)
Shiitake (Lentinula edodes) is a culinary-medicinal mushroom widely eaten in East Asian cuisine and sold in the UK as a food supplement, usually as dried fruiting-body powder or as a beta-glucan extract. There are no UK-authorised health claims for shiitake — claims for "immune support" and "natural defences" are on the EFSA Article 13 botanical hold list and have not been approved. The molecule with the strongest pharmacological track record is lentinan, a beta-(1-3,1-6)-glucan, but published clinical use of lentinan is mainly as an intravenous chemotherapy adjunct in Japan — not as an oral food supplement. Oral shiitake supplementation has been studied in small short-duration trials, mostly with proprietary beta-glucan extracts; results show modest immunological biomarker changes rather than hard clinical outcomes.
Camden Medicals editorial · Last reviewed 6 May 2026 · Next review May 2027
- Cross-checked against
- NHS
- NICE
- BNF
- EFSA
- FSA
Camden's editorial team independently graded each health claim below on the strength of the published evidence — see the grade beside every condition.
- Class
- Mushroom
- Typical daily dose
- Standardised beta-glucan extracts in trials: 1-3 mg/day (Lentinex® polysaccharide). Fermented rice-bran preparations: ~3 g/day. Crude dried fruiting-body powder: 100-500 mg/day per manufacturer convention, no published efficacy at these doses.
- Top use evidence
- Strong
On this page
What it is
Shiitake (Lentinula edodes, formerly Lentinus edodes) is a wood-decay fungus native to East Asia, cultivated commercially on hardwood logs or sawdust substrate. The edible fruiting body is the dark-brown cap and pale stem familiar from Asian cuisine. Dried shiitake retains most of the cell-wall polysaccharides — chiefly the beta-(1-3,1-6)-glucans — that are the focus of any medicinal interest.
The most studied single molecule from shiitake is lentinan, an isolated high-molecular-weight β-(1-3,1-6)-glucan. Lentinan was developed in Japan in the 1980s as an intravenous adjunct to chemotherapy for advanced gastric cancer and is licensed there as a hospital pharmaceutical. Oral lentinan has poor bioavailability and is not the same therapeutic preparation. Other research-relevant compounds in shiitake include eritadenine (a structural analogue of adenine that reduces serum cholesterol in animal models) and ergothioneine (an unusual sulphur-containing antioxidant amino acid present at higher levels in shiitake than in most foods).
UK food-supplement-grade shiitake is sold either as crude dried fruiting-body powder, as mycelial biomass, or as standardised beta-glucan extracts (e.g. Lentinex®, the GlycaNova preparation that holds EFSA Novel Food status). The cost-per-gram and the clinical-evidence footprint differ markedly between these forms — and so does the regulatory path. Generic dried-mushroom powder in a multi-mushroom blend is a different product class from a standardised extract.
At a glance
- No UK-authorised health claim. Marketing must stay descriptive. The "immune health" wording (EFSA ID 2075) is on the botanical-claims hold list, not approved.
- Two distinct clinical bodies of evidence — they are not interchangeable: (a) intravenous lentinan as a Japanese chemotherapy adjunct; (b) oral beta-glucan extracts in small healthy-adult RCTs. Generic dried-mushroom powder has neither.
- Active compounds with a research footprint are lentinan (a β-(1-3,1-6)-glucan), eritadenine, and ergothioneine. Standardisation to one of these is the differentiator between premium and commodity shiitake products.
- Raw or undercooked shiitake can trigger flagellate erythema (shiitake dermatitis) — a well-documented hypersensitivity rash from intact lentinan. Cooked shiitake and processed extracts denature the trigger.
- Most "shiitake mushroom complex" supplements deliver fruiting-body powder at 100-300 mg/day per mushroom in a multi-mushroom blend — well below extract doses used in clinical trials.
What people use it for
Adults seeking general "immune support"
There is no UK-authorised health claim for shiitake or for beta-glucans for immune function. Marketing must therefore stay descriptive (e.g. "traditionally used in East Asian cuisine") rather than claiming an effect. Small RCTs of proprietary extracts (Lentinex®, RBEP fermented rice bran) have shown modest changes in immunological biomarkers — B-cell counts, IFN-γ — but no hard clinical endpoints. [5,6]
Some evidenceLimitedAdults using shiitake as a culinary mushroom in cuisine
Shiitake is a well-tolerated and nutritionally useful culinary mushroom. UK food-tier consumption (cooked) carries no specific safety concern in healthy adults. [7]
Popular, not provenInsufficientAnyone considering a shiitake supplement for cancer or as a chemotherapy adjunct
Discuss with your oncology team before starting any mushroom supplement. The Japanese-licensed lentinan is an INJECTABLE hospital pharmaceutical, not an oral supplement, and oral mushroom supplements are not a substitute. Concomitant supplements during chemotherapy should always be cleared with the prescribing oncologist. [8]
Popular, not provenInsufficientPeople who eat raw or lightly-cooked shiitake (carpaccio, tartare-style preparations)
Cook shiitake fully. Raw or undercooked shiitake is the documented trigger for flagellate erythema (shiitake dermatitis) — a striking whip-like rash that resolves within 1-3 weeks but is uncomfortable and recurrent on re-exposure. Heat denatures the lentinan epitopes that cause it. [9,10]
Some evidenceStrong
How it works
Beta-(1-3,1-6)-glucans are recognised by Dectin-1 and complement-receptor-3 (CR3) on innate immune cells (macrophages, neutrophils, dendritic cells), upregulating phagocytosis and cytokine release in pre-clinical models. Whether this signalling translates to a meaningful clinical effect in healthy adults at oral food-supplement doses is not established.
Common myths
Myth""Shiitake boosts your immune system.""
RealityThere is no UK-authorised "immune support" health claim for shiitake. The wording sits on the EFSA Article 13 botanical-claims hold list pending further evidence and Commission consideration. Trade marketing using "boost", "supports", or "natural defences" wording is not permitted under the GB/EU Nutrition and Health Claims Regulation. [11]
Myth""Shiitake fights cancer.""
RealityLentinan, an isolated polysaccharide from shiitake, is licensed in Japan as an intravenous chemotherapy adjunct for advanced gastric cancer — not as an oral supplement. Eating shiitake mushrooms or taking oral shiitake powder is not the same therapy. Anyone considering supplements during cancer treatment should consult their oncology team first. [5]
Myth""All shiitake supplements are the same.""
RealityThere is a meaningful difference between (a) crude dried fruiting-body powder, (b) mycelial biomass, and (c) standardised beta-glucan extracts. The clinical evidence — modest as it is — was generated almost entirely with category (c) at specific doses. Crude powder in a multi-mushroom blend at 150 mg/serving has no published efficacy data of its own.
Myth""Shiitake is always safe — it's just food.""
RealityCooked shiitake is well-tolerated. Raw or undercooked shiitake has caused well over 100 reported cases of flagellate erythema (shiitake dermatitis) in the literature — a striking whip-like rash. Cook shiitake fully. People with documented shiitake hypersensitivity should avoid it in any form. [9]
Common online questions
Synthesised from the questions UK shoppers most often ask online about Shiitake (Lentinula edodes). Each answer is editorial and links to its evidence in the Sources list below.
Will shiitake "boost" my immune system?
There is no UK-authorised health claim that says so. Some small short-duration trials of proprietary beta-glucan extracts have shown modest changes in immune-cell counts, but this is not the same as a clinically meaningful effect on infections, sick-days, or general health. Generic shiitake powder in a multi-mushroom blend has no clinical evidence of its own. [5]
Is shiitake safe in pregnancy?
Cooked shiitake at culinary food-tier intake carries no specific concern. Concentrated supplements have not been studied in pregnancy and there is no UK guidance recommending shiitake supplementation in pregnancy. Most professional advice is to stay at food-tier intake during pregnancy and discuss any concentrated mushroom supplement with your midwife or GP first.
Can I take shiitake if I'm on chemotherapy?
Talk to your oncology team before starting any mushroom or beta-glucan supplement during chemotherapy. The Japanese lentinan trials used an intravenous pharmaceutical preparation alongside chemotherapy — not an oral food supplement — and those results do not transfer to off-the-shelf shiitake capsules. Some chemotherapy regimens are sensitive to immunomodulator interactions; the safe default is "ask first". [8]
What''s the right dose of shiitake powder?
There is no UK-recommended dose. Trial doses of proprietary beta-glucan extracts have ranged 1-3 mg/day (Lentinex®) up to 3 g/day (RBEP fermented rice bran). Crude dried fruiting-body powder is dosed by manufacturer convention, typically 100-500 mg/day in a blend, with no efficacy data attached to the dose. Higher doses do not have stronger evidence. [5,12]
⚖️ The official position
What may lawfully be claimed about Shiitake (Lentinula edodes) in Great Britain. This is a regulatory position, not an evidence grade.
No health claim is authorised for this use in Great Britain.
Shiitake (Lentinula edodes) has a history of traditional use. Authorised health claims require a positive EFSA scientific opinion; none has been issued for this use.
🔬 Camden’s evidence review
The research Camden reviewed, graded on its strength. This is our own appraisal — it sits beneath the official guidance above, never above it.
Immune biomarker changes in healthy adults (oral beta-glucan extracts)
LimitedEvidencelimitedTwo small randomised double-blind crossover/parallel trials of proprietary beta-glucan extracts (Lentinex® at 2.5 mg/day in healthy elderly; RBEP fermented rice bran at 3 g/day in healthy adults) reported modest, statistically significant changes in B-cell counts and IFN-γ secretion respectively, with no significant adverse effects. Neither trial measured clinical endpoints (infection rates, sick-days). Quality-of-life improvement was reported in a 2020 Lentinex® trial. None of these proprietary preparations is the same product as generic dried shiitake powder. [5,6,12]
Adjunctive treatment in advanced gastric cancer (intravenous lentinan)
ModerateEvidencemoderateLentinan is licensed in Japan as an intravenous adjunct to chemotherapy for advanced gastric cancer. Japanese trials suggest survival and quality-of-life benefits when added to S-1 or other regimens. UK relevance is limited: lentinan is not licensed in the UK as a medicine, the route is intravenous (not oral), and the preparation is a regulated pharmaceutical, not a food supplement. Oral mushroom supplements are not equivalent. [5,13]
Cholesterol reduction (eritadenine, animal models)
InsufficientEvidenceinsufficientEritadenine reduces plasma cholesterol in rodent models. There is no robust human RCT data at food-supplement doses. Not currently a clinical use case for shiitake supplementation.
General "wellness" and "energy"
InsufficientEvidenceinsufficientNo UK-authorised claim. No high-quality RCT evidence. Marketing this way is not permitted under the Nutrition and Health Claims Regulation.
Safety
Cooked shiitake at food-tier intake is well-tolerated. Concentrated shiitake supplements have a thin clinical-evidence base in healthy adults; raw or undercooked shiitake can cause flagellate erythema (shiitake dermatitis); chemotherapy patients should not start any mushroom supplement without their oncology team's input.
Talk to your pharmacist or GP first if you:
- You are receiving cancer treatment or are immunosuppressed (post-transplant, biologic-DMARD therapy, HIV) — mushroom beta-glucans interact theoretically with immune signalling and your oncology / immunology team should approve any supplement.
- You have a history of mushroom hypersensitivity or have ever had a flagellate-erythema reaction to shiitake.
- You take warfarin or other anticoagulants — high-dose mushroom supplements have weak theoretical INR-interaction signals and your INR should be checked if starting.
- You are pregnant or breastfeeding and considering a concentrated shiitake supplement (food-tier shiitake in cuisine is fine; concentrated supplements are unstudied).
Common side effects: Generally well-tolerated at food-tier intake. Concentrated supplements: occasional GI upset (loose stools, bloating). Rare: flagellate erythema from raw or undercooked exposure.
Pregnancy and breastfeeding
Cooked shiitake at culinary food-tier intake carries no specific concern. Concentrated shiitake supplements are unstudied in pregnancy. Default position: stay at food-tier intake; discuss concentrated supplements with your midwife or GP.
As pregnancy — culinary intake fine; concentrated supplements unstudied; default to food-tier intake.
Talk to your GP, midwife, or pharmacist before starting any supplement during pregnancy or breastfeeding.
More clinical detail (for clinicians and informed readers)
Contraindications
- Documented mushroom or shiitake hypersensitivity.
- Active immunosuppression for transplantation or biologic therapy — discuss with prescribing team.
Drug interactions
- Warfarin / DOACs — theoretical interaction (case reports of INR shifts with high-dose mushroom supplements). Monitor INR if starting; the signal is weak but documented.
- Immunosuppressants (ciclosporin, tacrolimus, mycophenolate, biologic DMARDs) — theoretical antagonism. Discuss with prescriber before starting any mushroom supplement.
- Cytotoxic chemotherapy — no documented direct interaction, but immunomodulator supplements during chemotherapy should be cleared with the oncology team as a matter of routine.
This is not an exhaustive list. Always tell your prescriber and pharmacist about every supplement you take.
Common side effects
- Generally well-tolerated at culinary intake.
- GI symptoms (bloating, loose stools) occasionally reported with concentrated supplements.
Rare side effects
- Flagellate erythema (shiitake dermatitis) — whip-like linear rash on trunk and limbs, 1-3 weeks duration, recurrent on re-exposure, primarily from raw or undercooked shiitake.
- Allergic reactions including urticaria and respiratory symptoms in occupational mushroom-cultivation workers.
How to take it
- Typical supplemental range
- Standardised beta-glucan extracts in trials: 1-3 mg/day (Lentinex® polysaccharide). Fermented rice-bran preparations: ~3 g/day. Crude dried fruiting-body powder: 100-500 mg/day per manufacturer convention, no published efficacy at these doses.
- Timing
- No specific timing requirement.
How to spot quality
Look for
- Species named in full: "Lentinula edodes" (the renamed accepted binomial; older labels say "Lentinus edodes").
- Part of the mushroom declared: "fruiting body" is the well-studied part. "Mycelium" or "myceliated grain" is a different — and less-studied — preparation.
- Standardisation: a declared β-(1-3,1-6)-glucan percentage (for extracts) or a declared starch:polysaccharide test result. Crude "shiitake powder" with no spec is the commodity tier.
- Substrate disclosure for cultivated mushroom mycelium: hardwood vs grain. Grain-substrate mycelium is largely undigested grain by weight, not mushroom.
- GMP-certified manufacture; ideally a heavy-metals screen (mushrooms accumulate heavy metals from substrate).
Red flags
- "Boosts immune system" or "natural defences" marketing — not a permitted UK claim.
- "Cancer" or "tumour" wording — not a permitted claim and conflates the IV pharmaceutical lentinan with food-supplement powder.
- Lentinan content claimed without a milligram declaration or without a third-party assay.
- Raw shiitake powder or "raw mushroom" preparations — culinary advice is to cook shiitake; raw forms can trigger flagellate erythema.
- Multi-mushroom blends with no per-mushroom milligram declaration ("proprietary blend 1500 mg") — you cannot work out the dose of any single mushroom.
Commonly combined with
Other ingredients that share a biological pathway, cofactor relationship, or evidence-backed protocol with this one. Mechanisms below cite primary physiology — not folk pairing. Doses are literature ranges, not recommendations. Talk to your pharmacist or GP before changing your stack, especially if you take prescription medication.
Maitake (Grifola frondosa)
Limited evidenceMycofera mushroom-cluster siblings — both contain β-(1-3,1-6) glucan with overlapping immune-cell-modulation mechanism.
Both species deliver β-(1-3,1-6) glucan that engages Dectin-1 on innate immune cells. Shiitake also contains lentinan (a high-molecular-weight isolate). Maitake contributes D-fraction polysaccharide. Mechanism additive on innate-immune signalling axis. Camden NB-502 Mushroom Complex bundles both.
Evidence: Mechanism complementary; combination trials in NB-502 Mushroom Complex framework.
Doses studied: 300 mg shiitake + 300 mg maitake fruiting-body extracts daily.
Found in Camden: Mycofera™ Mushroom Complex 120 Capsules
Beta-Glucan (β-glucan)
Limited evidenceShiitake β-(1-3,1-6) glucan is the canonical Mycofera-cluster active. Camden beta-glucan is the molecular pillar.
Shiitake fruiting-body delivers β-(1-3,1-6) glucan via Dectin-1 receptor; oat / barley β-(1-3,1-4) glucan delivers cholesterol claim. Different glucan classes, different regulatory positions.
Evidence: Camden beta-glucan covers cluster.
Doses studied: 300-1000 mg shiitake extract + ≥3 g/day oat β-glucan for the cholesterol claim threshold.
Found in Camden: Mycofera™ Mushroom Complex 120 Capsules
Vitamin C
Limited evidenceUK-authorised immune claim from vitamin C complements shiitake's no-authorised-claim immune narrative.
Vitamin C carries the UK Article 13.1 immune claim shiitake cannot. Shiitake provides the traditional polysaccharide-immune adjunct framing.
Evidence: UK Article 13.1 vitamin-c immune claim authorised. [11]
Doses studied: 300-1000 mg shiitake extract + 80-1000 mg vitamin C daily.