Cloud Ear

Metadata

Regulatory Status

China

• Chinese Pharmacopoeia: Listed within the Auricularia medicinal complex (Mu Er); A. polytricha/cornea and A. auricula-judae are both used under the broader Mu Er designation
• TCM classification: Sweet flavor, neutral temperature; enters large intestine, stomach, and liver channels
• TCM functions: Activates blood circulation (huo xue), dissolves blood stasis (hua yu), moistens the lungs, nourishes yin, lubricates the intestines
• Widely cultivated — one of the major Auricularia species in commercial production alongside A. heimuer
• Distinguished from Hei Mu Er (black wood ear, A. heimuer/auricula-judae) by its more hairy undersurface and lighter coloration

United States

• Available as food and dietary supplement
• Sold commonly in Asian grocery stores (usually labeled as “black fungus” or “cloud ear”)
• No FDA GRAS formal assessment
• Dietary supplement products available containing Auricularia extracts (often not species-differentiated)

Japan / Korea

• Widely consumed culinary mushroom
• No specific pharmaceutical approval
• Used in traditional medicine alongside other Auricularia species

European Union

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

Taxonomic Note

The name Auricularia polytricha is used in the majority of published research and commercial trade. However, molecular phylogenetic studies (Wu et al., 2015; Looney et al., 2013) indicate that A. polytricha (described from India in 1834) is likely a synonym of the earlier-described A. cornea (Ehrenberg, 1820). Much of the commercial “cloud ear” in Asian markets may be A. cornea sensu stricto. This monograph uses A. polytricha as the primary name given its prevalence in existing literature, while acknowledging the probable synonymy.

Conditions & Indications

Primary (Moderate Evidence from Auricularia Complex)

• Anticoagulant / Antithrombotic activity — Acidic polysaccharides from Auricularia species (including A. polytricha) significantly inhibit platelet aggregation, reduce thrombus formation, and prolong coagulation times (aPTT, PT, TT) in animal models. The 1980 Hammerschmidt case report in the New England Journal of Medicine first documented clinically significant antiplatelet effects in a human volunteer consuming Auricularia [Source: Hammerschmidt, 1980]
• Blood stasis syndrome (TCM) — Traditional primary indication; TCM practitioners prescribe cloud ear for conditions characterized by blood stagnation including dysmenorrhea, post-partum recovery, and vascular pain

Secondary (Preclinical to Moderate Evidence)

• Hyperlipidemia / Dyslipidemia — Auricularia polysaccharides reduce total cholesterol, triglycerides, and LDL-C while raising HDL-C in animal models; clinical evidence available for the Auricularia genus broadly [Source: Chen et al., 2008]
• Antioxidant / Anti-inflammatory — Polysaccharides and melanin pigments demonstrate significant free radical scavenging and anti-inflammatory activity in vitro and in animal models, with cardioprotective implications [Source: multiple preclinical studies]
• Antidiabetic — Auricularia polysaccharides improve glucose metabolism in diabetic animal models through enhanced insulin sensitivity and GLUT4 expression

Emerging/Preclinical

• Antitumor — Polysaccharide isolated from A. polytricha using high-speed countercurrent chromatography showed anticancer activity against multiple cancer cell lines [Source: Xia et al., 2011]
• Hepatoprotection — Polysaccharides protect against chemical-induced liver injury via NF-kappaB modulation
• Gut microbiome modulation — Prebiotic effects promoting beneficial gut bacteria and short-chain fatty acid production

Mechanism of Action

Primary Mechanisms

1. Acidic polysaccharide-mediated anticoagulant activity: Cloud ear contains unique acidic heteropolysaccharides with alpha-1,3-linked mannose/glucose backbone, extensively branched with glucuronic acid and xylose. The polysaccharide AAP-b2 from Auricularia has a monosaccharide composition of mannose, glucuronic acid, glucose, and xylose (molar ratio 89.25:30.50:4.25:1.00). The high glucuronic acid content enables:

   • Antithrombin III (AT-III) enhancement — heparin-like mechanism where polysaccharides potentiate AT-III’s inhibition of thrombin (Factor IIa) and Factor Xa
   • Protein C pathway activation — enhancement of anticoagulant protein C activity
   • Prolongation of aPTT, PT, and TT — indicating broad-spectrum coagulation cascade inhibition

2. Antiplatelet activity through multiple pathways:

   • Endothelial regulation: Modulation of eNOS (endothelial nitric oxide synthase), ET-1 (endothelin-1), PGI2 (prostacyclin), and TXB2 (thromboxane B2)
   • Adenosine-mediated: Adenosine activates platelet A2A receptors, increasing cAMP and inhibiting platelet activation
   • Direct platelet inhibition: Polysaccharides interfere with fibrinogen-GPIIb/IIIa binding and collagen-vWF interactions

3. Lipid metabolism modulation:

   • Intestinal bile acid binding and fecal excretion
   • LDL receptor upregulation on hepatocytes
   • Partial HMG-CoA reductase modulation
   • Anti-inflammatory effects on vascular endothelium

Secondary Mechanisms

• Melanin-mediated antioxidant activity: Eumelanin-type pigments scavenge superoxide and hydroxyl radicals; chelate transition metal ions preventing Fenton reaction-mediated oxidative damage
• Dietary fiber prebiotic effects: Glucomannan and chitin serve as fermentation substrates for beneficial gut microbiota
• Anti-inflammatory: Polysaccharides suppress NF-kappaB signaling and reduce TNF-alpha and IL-6 in inflammatory models

Pharmacological Distinction from A. auricula-judae

While the mechanisms are broadly shared with A. auricula-judae, structural analysis of polysaccharides suggests that A. polytricha/cornea may have somewhat different monosaccharide ratios and molecular weights, potentially leading to different potencies for specific activities. However, this has not been systematically compared in head-to-head studies. [NEEDS-RESEARCH]

Clinical Evidence Summary

Key Studies (Auricularia Complex — Species Attribution Often Uncertain)

Evidence Limitations

• Many clinical studies use “Auricularia auricula” broadly without species-level identification; results may reflect A. heimuer, A. cornea/polytricha, or A. auricula-judae
• No clinical trials specifically designed to evaluate A. polytricha/cornea as distinct from other Auricularia species
• Most trials are in Chinese-language journals with limited international peer review
• Moderate sample sizes and short durations in available trials
• No long-term cardiovascular outcome trials
• Polysaccharide extraction and standardization varies across studies
• The 1980 Hammerschmidt NEJM case report, while landmark, was a single case observation

Safety Profile

General Assessment

Cloud ear has been consumed as a staple food across Asia for over a millennium. Annual consumption in China alone runs into millions of tonnes across all Auricularia species. The culinary safety record is excellent. However, like A. auricula-judae, clinically significant anticoagulant and antiplatelet activity creates important medical considerations.

Contraindications

• Bleeding disorders or thrombocytopenia
• Pre-surgical: discontinue concentrated supplements at least 2 weeks before surgery
• Concurrent anticoagulant therapy (warfarin, DOACs) or antiplatelet therapy (aspirin, clopidogrel): additive bleeding risk

Drug Interactions

Food Safety Warning: Bongkrekic Acid

As with all Auricularia species, prolonged soaking of rehydrated cloud ear at warm temperatures (>25 degrees C for >24 hours) can support growth of Burkholderia gladioli pv. cocovenenans, producing bongkrekic acid — a lethal mitochondrial toxin responsible for fatal poisoning outbreaks in China and Southeast Asia. Prevention: Rehydrate in cold water for 2-4 hours maximum; refrigerate during soaking if longer; discard specimens 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 or in combination with anticoagulant medications

Toxicology

• No specific LD50 data for A. polytricha; Auricularia genus broadly shows excellent safety in animal toxicology studies (no adverse effects at 15 g/kg oral)
• 90-day feeding studies with Auricularia polysaccharides: no adverse effects
• Ames test negative (genus-level data)

Clinical Dosage

Dried Fruiting Body (Culinary/Traditional)

• Dietary: 5-15 g/day dried, rehydrated and cooked
• Always cook thoroughly; never consume raw or after prolonged warm soaking
• Cloud ear expands 5-10x when rehydrated

Polysaccharide Extract (Supplement)

• Standard: 1-3 g/day hot water polysaccharide extract (based on Auricularia genus evidence)
• Clinical trial reference doses: 1-1.5 g/day polysaccharide (genus-level studies)
• Minimum 30% polysaccharide content for quality extract

Traditional TCM Decoction

• 6-12 g dried cloud ear simmered in 500 mL water for 30-60 minutes
• Common combinations: with red dates and goji berries for blood nourishing; with lotus root for cardiovascular support; with lily bulb for lung moistening

Quality Considerations

• Species identification within the Auricularia genus is challenging without molecular testing
• Cloud ear (A. polytricha/cornea) is typically lighter in color and more hairy on the underside compared to wood ear (A. auricula-judae/heimuer)
• Dark-colored specimens generally indicate higher melanin/antioxidant content
• Avoid SO2-bleached products
• Hot-water extraction needed for optimal polysaccharide bioavailability
• Source from reputable cultivators using clean substrates to avoid heavy metal contamination

Sources

• Hammerschmidt DE. Szechwan purpura. N Engl J Med. 1980;302(19):1191-1193
• 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
• Chen G, et al. Hypocholesterolemic effects of Auricularia auricula ethanol extract in ICR mice fed a high-fat diet. J Food Sci Technol. 2008;52(6):1-7
• Yuan Z, et al. Effects of Auricularia auricula polysaccharide on hemorheology in rats. Biosci Biotechnol Biochem. 1998;62(10):1898-1903
• Xia F, et al. Isolation of a polysaccharide with anticancer activity from Auricularia polytricha using high-speed countercurrent chromatography with an aqueous two-phase system. J Chromatogr A. 2011;1218(49):9010-9014
• Wu F, et al. Global diversity and updated phylogeny of Auricularia (Auriculariales, Basidiomycota). J Fungi. 2021;7(11):933
• Cai M, et al. Extraction optimization, structural characterization, and anticoagulant activity of acidic polysaccharides from Auricularia auricula-judae. Molecules. 2020;25(3):710
• A novel polysaccharide from Auricularia auricula alleviates thrombosis induced by carrageenan in mice. Oxid Med Cell Longev. 2022;2022:4054857
• Chinese Pharmacopoeia Commission. Pharmacopoeia of the People’s Republic of China. 2020 Edition
• Lowy B. A morphological basis for classifying the species of Auricularia. Mycologia. 1952;44(5):699-727

Connections

• Closely related to Wood Ear (A. auricula-judae) — same genus with overlapping cardiovascular pharmacology; A. polytricha/cornea is the “cloud ear” to A. auricula-judae’s “wood ear,” but species boundaries and bioactive differences remain poorly resolved
• Compare with Tremella — both gelatinous ear-type mushrooms but pharmacologically distinct: Tremella’s acidic polysaccharides drive moisture retention (skin/cosmetic), while Auricularia’s drive anticoagulant activity (cardiovascular)
• Compare with Reishi — both demonstrate antiplatelet activity; Reishi primarily through adenosine and ganoderic acids, Auricularia through acidic polysaccharide + adenosine combination
• Compare with Shiitake — complementary cardiovascular mechanisms: shiitake’s eritadenine lowers cholesterol while lenthionine provides antiplatelet effects; commonly combined in Chinese cooking
• The heparin-like anticoagulant mechanism via acidic glucuronoxylomannan polysaccharides is shared across the Auricularia genus and is rare among other medicinal mushroom genera
• The 1980 NEJM Hammerschmidt case report specifically referenced A. polytricha, making it a landmark species in the recognition of mushroom-drug interactions