✓ No active regulatory warningsFDA MedWatch, EMA EudraVigilance, WHO VigiBase, WADA Prohibited List · 2026-05-29
📰Read the full Shiitake Extract evidence review on GMJ News →Complete clinical article, references and updates on news.gmj.ge. This page is the structured safety summary.⚠ IV lentinan (Japan Rx) ≠ oral shiitake supplement [1]
⚠ Sun-dried shiitake: 30 min sunlight converts ergosterol → vitamin D2 [1]
⚠ Transplant patient — immunostimulation from beta-glucans [1]
ℹ️ Not obtained from food. Not applicable — this is not obtained from food in meaningful amounts; supplementation is the practical route.
🔬 Lab interpreter
ℹ️ No validated blood test. There is no established laboratory test to assess status or guide dosing for this ingredient. Clinical response and symptoms are the practical guide.
⚕ For professionals — confirm ranges against your local laboratory.
Clinical verdict
Shiitake produces lentinan — an injectable cancer adjuvant approved in Japan since 1985. Oral shiitake/extract has modest immune evidence but is NOT equivalent to IV lentinan for cancer. UV sunlight trick: expose dried shiitake to sun for vitamin D2 production. Eritadenine may lower cholesterol. Excellent culinary mushroom [1] [2].
1 How much do I need?
👤 Adults: Specific dosage data under clinical review
👴 Elderly: Specific dosage data under clinical review
🤰 Pregnancy: See guidance
Safe as food. Extract: limited data [1].
👦 Pediatric: See guidance
Food — safe. Extract: no data [1].
🏃 Athletes: Standard dose
⚖️ Obesity: Standard dose
Fat-soluble compounds may require dose adjustment in obesity.
🩺 Renal: Consult specialist
Dose adjustment may be needed in renal impairment.
🌱 Vegan: Standard dose
How to take
🍽 Timing: Any time [1].
💊 With food: Culinary mushroom — eat as food [1].
🚫 Avoid: Immunosuppressants [1].
2 Which form?
| Form | Bioavailability | Vegan | Cost |
|---|---|---|---|
| ['Shiitake whole mushroom (fresh/dried)', 'common', 'Culinary + medicinal. Sun-dried = vitamin D2 [1].'] | Standard | Check label | |
| ['Shiitake extract (lentinan-enriched)', 'preferred', 'Concentrated beta-glucans [2].'] | Standard | Check label | |
| ['Lentinan injection (Japan Rx)', '', 'IV cancer adjuvant. Not available as OTC [1].'] | Standard | Check label |
3 Common questions
Is eating shiitake as good as lentinan injection? ▼
No — lentinan injection delivers purified beta-glucan directly to the bloodstream. Oral shiitake provides beta-glucans that must survive digestion. The cancer adjuvant evidence is for IV lentinan, not oral mushroom consumption [1].
Vitamin D trick? ▼
Place dried shiitake gill-side UP in direct sunlight for 30–60 minutes. Ergosterol in mushroom → vitamin D2 via UV conversion. This works and significantly increases D2 content [1].
4 Clinical evidence
Strong
Lentinan (IV) as cancer adjuvant: approved in Japan since 1985 for gastric cancer. Meta-analyses show improved survival when combined with chemo [1]. UV-exposed shiitake produces vitamin D2 [1]. HIGH
Moderate
Immune function: oral shiitake extract improved immune markers (NK cells, sIgA) in small trials [2]. Cholesterol: eritadenine reduced cholesterol in animal models and small human studies [1]. Oral shiitake consumption: one trial (n=52) showed improved immune cell patterns with 4 weeks of daily shiitake consumption [2]. MODERATE
Insufficient
5 Safety, toxicity & adverse events
Absolute contraindications
✕ Mushroom hypersensitivity
Relative
⚠ Autoimmune disease — immune-activating
⚠ Can cause 'shiitake dermatitis' (flagellate rash) with raw/undercooked intake
⚠ Pregnancy and lactation — limited data on concentrated extracts
🚩 Red flags
● Patient eating RAW shiitake — shiitake dermatitis risk. Must cook [1]
6 Interactions
Drug interactions
Immunosuppressants Moderate
Mechanism: Beta-glucan immunostimulation. [1]
Effect: May oppose immunosuppression. [1]
Action: Avoid in transplant patients [1].
Supplement synergies
Reishi + Turkey Tail · Standard doses
Comprehensive mushroom immune stack [1].
Comprehensive mushroom immune stack [1].
7 Regulatory
Japan: Lentinan: approved injectable cancer adjuvant since 1985 [1].
United States: Food (GRAS). Extract: dietary supplement [1].
8 Cite this page
Vancouver: Pkhakadze G. Shiitake Extract — safety profile [Internet]. Tbilisi: PHIG; 2026 [cited 2026 Aug 15]. Available from: https://supplement.ge/ingredients/shiitake-extract/
APA 7th: Pkhakadze, G. (2026). Shiitake Extract — Safety profile. Public Health Institute of Georgia. https://supplement.ge/ingredients/shiitake-extract/
📋 Editorial information
Author: Prof. G. Pkhakadze, MD, MPH, PhD
Institution: Public Health Institute of Georgia (PHIG)
Affiliation: David Tvildiani Medical University (DTMU)
First published: January 2026
Last reviewed: 2026-05-29
Next review: February 2027
References: 2 cited sources
COI: SupplementIndex receives no funding from supplement manufacturers. All content independently authored by PHIG.
Process: Systematic literature review
📄 License & reuse
Published under Creative Commons Attribution 4.0 International (CC BY 4.0). You may share and adapt for any purpose with attribution.
Pkhakadze G. "Shiitake Extract — Safety Profile." SupplementIndex, PHIG, 2026. https://supplement.ge/ingredients/shiitake-extract/ CC BY 4.0.
GP
Prof. G. Pkhakadze, MD, MPH, PhD
Professor of Public Health · Head of Department, DTMU
Editor-in-Chief, Georgian Medical Journal (ISSN 3088-4322)
Chair, Public Health Institute of Georgia · UEMS Public Health Section
Educational and public health purposes. CC BY 4.0. Consult your healthcare provider before starting any supplement. Corrections: info@accreditation.ge. Publisher: PHIG