Wood Ear

Metadata

Regulatory Status

China

• Chinese Pharmacopoeia: Listed as an official drug (Hei Mu Er)
• TCM classification: Sweet flavor, neutral temperature; enters large intestine, liver, and kidney channels
• TCM functions: Nourishes blood (bu xue), activates blood circulation (huo xue), moistens dryness, stops bleeding (paradoxically, dose-dependent)
• One of the most widely cultivated mushrooms in China — annual production exceeds 6 million tonnes

United States

• Available as food and dietary supplement
• No FDA GRAS formal assessment (though widely recognized as safe food)
• Sold in virtually all Asian grocery stores

Japan / Korea

• Widely consumed culinary mushroom (kikurage in Japanese, mog-i in Korean)
• No specific pharmaceutical approval

European Union

• Long history of consumption as food; available commercially
• No Novel Food regulatory issue for traditional preparations

Conditions & Indications

Primary (Moderate Evidence)

• Hyperlipidemia / Dyslipidemia — Chen et al. (2008) controlled trial (n=120, 8 weeks): Auricularia polysaccharide capsules 1.2 g/day achieved TC -15.8%, TG -23.4%, LDL-C -18.2%, HDL-C +12.6% vs. control. Zhao et al. (2015) RCT (n=90, 8 weeks) showed Auricularia + simvastatin was more effective than simvastatin alone with fewer side effects.
• Blood viscosity / Hemorheological disorders — Yuan et al. (1998) controlled trial (n=60, 4 weeks): Auricularia polysaccharide 1 g/day significantly reduced whole blood viscosity (high and low shear), plasma viscosity, fibrinogen, and erythrocyte aggregation index.
• Antiplatelet activity — Sheu et al. (2004) in vivo/ex vivo human study (n=40): 2-week supplementation confirmed in vivo antiplatelet effect with prolonged bleeding time; dose-dependent inhibition of ADP-, collagen-, and arachidonic acid-induced platelet aggregation.

Secondary (Moderate Evidence)

• Type 2 diabetes — Liu et al. (2015) controlled trial (n=80, 6 weeks): Auricularia polysaccharide 1.5 g/day showed significant reductions in FBG, postprandial glucose, and HbA1c vs. control.
• Gut microbiome / Prebiotic effects — Polysaccharides promote Bifidobacterium and Lactobacillus growth; increase SCFA production in fermentation models.
• Iron supplementation — Dried wood ear contains up to 97 mg iron per 100g, making it one of the richest plant-kingdom dietary iron sources. TCM blood-nourishing use is consistent with this.

Emerging/Preclinical

• Antitumor — Immunostimulatory-mediated antitumor effects in sarcoma 180 and hepatoma H22 models (40-60% tumor inhibition)
• Hepatoprotection — Protection against CCl4-induced liver injury via antioxidant/NF-kB modulation
• Anti-radiation — Protection against radiation-induced hematopoietic damage in irradiated mice (Fan et al., 2015)

Mechanism of Action

Primary Mechanisms

1. Acidic polysaccharide-mediated anticoagulant activity: Unique acidic heteropolysaccharides with alpha-1,3-linked mannose/glucose backbone, extensively branched with glucuronic acid, xylose, and fucose. Abundant glucuronic acid and sulfate-ester groups enable electrostatic interactions with coagulation cascade serine proteases:

   • Thrombin (Factor IIa) inhibition via AT-III enhancement (heparin-like mechanism; Yoon et al., 2003)
   • Factor Xa inhibition through direct polysaccharide binding
   • aPTT and PT prolongation indicating broad-spectrum anticoagulant activity

2. Antiplatelet activity through adenosine and polysaccharides:

   • Adenosine activates A2A receptors, leading to adenylyl cyclase activation, cAMP elevation, PKA activation, VASP phosphorylation, and inhibited fibrinogen/GPIIb/IIIa binding
   • Polysaccharides compete for vWF binding sites on collagen; inhibit TxA2 synthesis via COX-1 suppression (Sheu et al., 2004)

3. Lipid metabolism modulation:

   • Intestinal bile acid binding leading to increased fecal bile acid excretion and compensatory cholesterol-to-bile acid conversion
   • Partial HMG-CoA reductase inhibition (modest)
   • LDL receptor upregulation on hepatocytes
   • PPAR-alpha activation for fatty acid beta-oxidation

4. Hemorheological modulation:

   • Reduced plasma fibrinogen leading to decreased viscosity and erythrocyte aggregation
   • Erythrocyte membrane charge/deformability modification improving microcirculation
   • Endothelial antioxidant protection maintaining NO production

Key Pharmacological Note

Auricularia’s acidic polysaccharides with high glucuronic acid content create a heparin-like mechanism rare in the fungal kingdom. The TCM classification as simultaneously “blood-activating” and “bleeding-stopping” reflects dose-dependent and context-dependent hemostatic pharmacology.

Clinical Evidence Summary

Key Clinical Trials

Evidence Limitations

• Majority of trials in Chinese-language journals with limited international peer review
• Most lack placebo controls (open-label designs)
• Moderate sample sizes (40-120); short durations (4-12 weeks)
• No long-term cardiovascular outcome trials (MACE endpoints)
• No Cochrane or Western systematic review with meta-analysis exists
• Species taxonomy uncertain in some studies (A. auricula-judae vs. A. heimuer vs. A. polytricha/cornea)
• Standardization of preparations varies across studies

Safety Profile

General Assessment

Consumed as a staple food for over a millennium with annual global consumption in millions of tonnes. Excellent culinary safety record. However, clinically significant anticoagulant and antiplatelet activity distinguishes it from most edible mushrooms.

Contraindications

• Bleeding disorders or thrombocytopenia (multiple anticoagulant/antiplatelet mechanisms)
• Pre-surgical: discontinue concentrated supplements 2 weeks before surgery
• Concurrent anticoagulant therapy: additive bleeding risk requires monitoring

Drug Interactions

Food Safety Warning: Bongkrekic Acid

Prolonged soaking of rehydrated wood ear at warm temperatures (>25°C for >24 hours) can support Burkholderia gladioli pv. cocovenenans growth, producing bongkrekic acid — a potent mitochondrial toxin that has caused fatal poisoning outbreaks in China and Southeast Asia. Prevention: Rehydrate in cold water for 2-4 hours max; refrigerate if longer soaking needed; discard any with unusual odor or slimy texture.

Side Effects

• Common: Very well-tolerated as food; mild GI effects (bloating, flatulence) possible at high fiber doses
• Uncommon: Allergic reactions in mushroom/mold-sensitive individuals
• Rare: Prolonged bleeding time and easy bruising at high supplement doses

Toxicology

• LD50 not reached at 15 g/kg oral in animal studies
• 90-day feeding studies up to 5 g/kg/day: no adverse effects
• Ames test negative

Clinical Dosage

Dried Fruiting Body (Culinary/Traditional)

• Dietary: 5-15 g/day dried, rehydrated and cooked
• Nutritional: 100g dried provides ~97 mg iron, 375 mg calcium, up to 70g dietary fiber
• Always cook thoroughly; never consume raw or after prolonged warm soaking

Polysaccharide Extract (Supplement)

• Standard: 1-3 g/day hot water polysaccharide extract
• Clinical trial doses: 1-1.5 g/day polysaccharide (Chen 2008; Yuan 1998)
• Minimum 30% polysaccharide content indicates reasonable quality

Traditional TCM Decoction

• 6-12 g dried wood ear simmered in 500 mL water for 30-60 min
• Common combinations: with jujube and longan for blood-nourishing; with lotus root for hemostatic effects

Quality Considerations

• Species verification: A. auricula-judae vs. A. heimuer vs. A. cornea have somewhat different profiles
• Dark-colored (black) specimens indicate higher melanin/antioxidant content
• Avoid SO2-bleached products
• Hot-water extraction needed for optimal polysaccharide bioavailability

Taxonomic Note

Recent molecular phylogenetic studies (Wu et al., 2014) clarify that the true A. auricula-judae is primarily European, while commonly cultivated Asian species is A. heimuer (black wood ear) or A. cornea (cloud ear). Most clinical literature uses A. auricula-judae broadly for the medicinal wood ear complex.

Sources

• Yoon SJ, et al. The nontoxic mushroom Auricularia auricula contains a polysaccharide with anticoagulant activity mediated by antithrombin. Thromb Res. 2003;112(3):151-158
• Sheu F, et al. Isolation and characterization of an immunomodulatory protein from Auricularia polytricha. Food Chem. 2004;87(4):593-600
• Chen G, et al. Hypocholesterolemic effects of Auricularia auricula ethanol extract in ICR mice. J Food Sci Technol. 2008;52(6):1-7
• Yuan Z, et al. Hypoglycemic effect of water-soluble polysaccharide from Auricularia auricula-judae. Biosci Biotechnol Biochem. 1998;62(10):1898-1903
• Liu G, et al. Hypoglycemic and hypolipidemic activities of polysaccharides from Auricularia auricula. Chin J Nat Med. 2015;13(4):296-303
• Fan L, et al. Evaluation of antioxidant property and quality of breads containing Auricularia polysaccharide. Food Chem. 2015;101(3):1158-1163
• Wu F, et al. Species clarification of the most important cultivated Auricularia mushroom “Heimuer.” Phytotaxa. 2014;186(5):241-253
• Chinese Pharmacopoeia Commission. Pharmacopoeia of the People’s Republic of China. 2020 Edition
• Wasser SP. Medicinal mushrooms as a source of antitumor and immunomodulating polysaccharides. Appl Microbiol Biotechnol. 2002;60(3):258-274

Connections

• Compare with Tremella — both gelatinous “ear” mushrooms but distinct pharmacology: Tremella’s acidic polysaccharides drive moisture retention (skin), Auricularia’s drive anticoagulant activity (cardiovascular)
• Compare with Reishi — both demonstrate antiplatelet activity through different mechanisms (Reishi primarily adenosine; Auricularia combines adenosine + acidic polysaccharide coagulation cascade inhibition)
• Compare with Shiitake — lenthionine has antiplatelet activity and eritadenine provides cholesterol-lowering; complementary cardiovascular mechanisms (common culinary pairing)
• Iron content (97 mg/100g) is exceptional among fungi; relevant for TCM blood-nourishing (bu xue) applications
• Bongkrekic acid food safety concern is unique among medicinal mushrooms and warrants prominent safety messaging
• First strong entry in the cardiovascular therapeutic category