Yin Er (Fruiting Body of Tremella, Wood Ear)

Chinese Herb Actions

Chinese Herb Dosage

• What is the typical dosage of Yin Er, and how is it prepared?

  3–9 g in decoction — our record gives the same range from both Chen and Bensky, an unusually clean agreement between sources. In everyday use, however, Yin Er is far more often cooked than decocted: a small handful of the dried fungus is soaked until it swells, trimmed of its hard base, and simmered slowly for an hour or more until the water thickens into a light syrup.

  • Part used — the dried fruiting body.
  • Soaking — dried Yin Er expands dramatically, so a very small dry weight makes a full bowl. Soak in cool water; discard the yellowish stem base.
  • Long, gentle cooking — the gelatinous mouthfeel that defines the dish only develops with extended simmering. Short boiling leaves it rubbery.
  • Food-medicine dosing — because it is eaten as food, the practical amount in a dessert soup is often in the same low-gram range as the decoction dose. The safety margin here is generous by materia medica standards.
  • One preparation caution — soaked fungus is perishable. See the cautions section; this is the one genuine safety point for an otherwise very gentle food.

  Source: our own herb record dosage field (Chen and Bensky ranges recorded) and part used; culinary preparation cross-referenced against multiple online sources. Reference only — not a prescription.

Chinese Herb Contraindications & Cautions

• Are there cautions for Yin Er, and is it safe to eat?

  Yin Er is one of the gentlest substances on this site and is eaten as ordinary food, but there is one real and serious caution — and it concerns storage and spoilage, not the fungus itself. Our record’s own caution is a pattern caution: use with care where a cough is due to wind-cold, since a moistening, yin-nourishing substance is the wrong direction for an external cold pattern.

  • Pattern cautions — not appropriate for wind-cold cough, and, like other rich moistening substances, best used thoughtfully where there is damp, phlegm or a weak, easily overwhelmed digestion.
  • Spoiled or over-soaked fungus — a documented and severe food-safety hazard. Deteriorated fresh tremella, and fungus left soaking too long, can support Burkholderia gladioli pathovar cocovenenans, which produces bongkrekic acid, a heat-stable mitochondrial toxin that cooking does not destroy. Chinese national surveillance recorded 19 foodborne bongkrekic acid outbreaks between 2010 and 2020, with 146 illnesses, 139 hospitalisations and 43 deaths — a case-fatality rate of 29.5%. Tremella was among the recorded vehicles, alongside homemade fermented corn products, sweet potato and corn flour jelly, wet rice noodles and black fungus (Auricularia). The practical rule that follows is simple: soak only for as long as needed, soak in the refrigerator if soaking longer, discard anything slimy, discoloured or off-smelling, and never eat fungus that has been left standing in water at room temperature for many hours or overnight.
  • Proportion — this is a hazard of spoilage, not a property of the herb. Properly dried, properly stored and briefly soaked Yin Er has an unremarkable safety record and a very long history as everyday food. The point is stated here because it is well documented and because the exposure route is a normal kitchen step.
  • Allergy — as with any edible fungus, individual sensitivity is possible.

  Source: our own herb record cautions field; bongkrekic acid surveillance per PMID 36630445, PMC 9833544, DOI 10.1371/journal.pone.0279957 and PMID 34594817, PMC 8393157, DOI 10.46234/ccdcw2020.264. Neutral reference information — not medical advice.

Chinese Herb Toxicity & Overdose

• Yin Er itself is non-toxic. It is a food fungus with a long dietary history and no toxicity recorded in our own record or in the materia medica literature, and the human trials below reported no excess of adverse events over placebo. The only documented lethal hazard associated with tremella is external to the fungus: contamination of spoiled or excessively soaked material with Burkholderia gladioli pathovar cocovenenans and its heat-stable toxin bongkrekic acid, which cooking cannot remove. That risk is one of food handling and storage — see the cautions section — and it applies equally to black fungus and to several starch-based foods.

  Source: our own herb record (no toxicity entry recorded); tolerability per PMID 29319408, DOI 10.1089/jmf.2017.4063 and PMID 38439104, PMC 10913275; contamination hazard per PMID 36630445, PMC 9833544. Neutral reference information, not a safety guarantee.

Herb-Drug Interactions

• No well-established clinical herb–drug interactions are documented for Yin Er. One area is worth practitioner awareness rather than alarm: a 12-week randomised controlled trial in overweight and obese prediabetic adults reported a small reduction in HbA1c with a tremella beverage, so anyone on glucose-lowering medication who takes concentrated tremella preparations regularly is reasonably monitored by their prescriber. The effect size was modest and the study exploratory; this is precautionary, not a demonstrated interaction. Culinary amounts in a dessert soup are not the same exposure. (Flagged for practitioner confirmation.)

  Source: PMID 38439104, PMC 10913275, DOI 10.1186/s40795-024-00842-0. Precautionary; not a demonstrated drug interaction.

Western / Biomedical Research

Chinese Herb Clinical Studies & Research

Provided as research context — a summary of published biomedical study, not a therapeutic or medical claim.

• Is there research on Yin Er (Tremella fuciformis)?

  Yes — a large laboratory literature on its polysaccharides and two small human randomised trials. Tremella fuciformis polysaccharide is among the better-characterised fungal polysaccharides, and it is what gives the soaked fungus its gel. Reviews describe its structure, water-holding capacity and antioxidant, immunomodulatory and metabolic activities. The human evidence is genuinely thin by comparison, and we record both accurately.

  • Cognition (randomised, double-blind, placebo-controlled) — 75 adults with subjective cognitive impairment took tremella at 600 mg/day or 1,200 mg/day, or placebo, for 8 weeks. The tremella groups showed greater improvement in a subjective memory complaint questionnaire and in short-term memory and executive function tests, with adverse-event rates comparable across all three groups. Small, short, single-centre, and a manufactured supplement rather than a decoction.
  • Prediabetes (randomised, double-blind, placebo-controlled) — 56 overweight or obese prediabetic adults drank a tremella β-glucan beverage or placebo daily for 12 weeks. HbA1c fell from 6.03% to 5.96% (p = 0.047, Cohen’s d = 0.39) and waist circumference from 95.2 cm to 93.5 cm (p = 0.022), with no adverse events. The authors describe the study as exploratory and call for larger trials; the absolute changes are small.
  • Skin and barrier (preclinical) — a dermatology review summarises laboratory and animal work on tremella extract in skin ageing, photoprotection, wound healing and barrier function, and states plainly that most studies are in vitro or in animals and that clinical research is still needed.
  • Polysaccharide pharmacology (preclinical) — published work reports immunomodulatory activity dependent on acetylation, gut-microbiota modulation and reduced fat accumulation in high-fat-diet mice, and antioxidant effects in cultured skin fibroblasts. Cell and animal models throughout.

  Reading the evidence honestly. Both human trials used standardised tremella supplements or beverages taken alone for a biomedical endpoint. Neither studied Yin Er as Chinese medicine uses it — a low-gram food-medicine, inside a dish or a formula, selected on a yin-deficiency pattern. The laboratory findings on polysaccharides are consistent with the traditional reading of a moistening, fluid-generating substance, but consistency is not confirmation, and none of this is a treatment claim.

  Sources: PMID 29319408, DOI 10.1089/jmf.2017.4063 (cognition RCT); PMID 38439104, PMC 10913275, DOI 10.1186/s40795-024-00842-0 (prediabetes RCT); PMID 36757441, DOI 10.1007/s00403-023-02550-4 (dermatology review); PMID 36142298, PMC 9499394 (acetylation and immunomodulation); PMID 36545204, PMC 9760882 (gut microbiota, mice); PMID 28627707, PMC 5561887 (skin fibroblasts, in vitro). Research context only — not a therapeutic claim.

Chinese Herb Notes

• Is Yin Er the same as wood ear (Mu Er)?

  No. They are two different fungi, and the overlap in our record’s naming is worth untangling. Yin Er is Tremella fuciformis, the white or silver ear — also called Bai Mu Er (“white wood ear”), which is where the phrase “wood ear” enters our own record. Plain Mu Er or Hei Mu Er (“black wood ear”) refers to a completely different fungus, Auricularia, which is dark brown to black, thin, ear-shaped, and used as a savoury vegetable rather than a sweet one.

  • Yin Er / Bai Mu Er — Tremella fuciformis; white, frilly, translucent; sweet and bland, neutral; a yin-moistening food-medicine, almost always cooked sweet.
  • Mu Er / Hei Mu Er — Auricularia; black, flat, ear-shaped; a distinct fungus with its own culinary and dietary tradition, not the substance described on this page.
  • Why it matters — recipes, suppliers and translations use “wood ear” loosely for both. If a source calls for “wood ear” in a sweet, moistening context it almost certainly means Yin Er; in a savoury stir-fry it almost certainly means the black one.

  Naming note flagged for review (not changed): our record’s common-name field reads “Fruiting Body of Tremella, Wood Ear.” The unqualified phrase “Wood Ear” is a fair rendering of the alternate name Bai Mu Er but is easily read as the black wood ear (Auricularia), which is a different fungus. Left unchanged pending owner confirmation.

  How is Yin Er traditionally eaten?

  As a sweet soup. Our own record notes the classic combination: Yin Er simmered with Long Yan Rou (longan flesh), Lian Zi (lotus seed) and rock sugar in water. Red dates, goji berries, pear and snow fungus variations are all part of the same everyday family of dishes. This is one of the clearest examples on the site of the Chinese principle that food and medicine share a source: the dessert and the prescription are the same preparation, taken with different intent.

  • Why the pairing works traditionally — the added ingredients are moistening and gently nourishing, and rock sugar itself is regarded as moistening to the Lung, so the whole bowl points the same direction as the fungus.
  • Dietary status — entirely plant-kingdom (fungal) and suitable for vegetarians and vegans, unlike several other yin tonics.

  How does Yin Er compare with the other yin tonics?

  It is the mildest and the most food-like. Where Sha Shen, Mai Men Dong and Yu Zhu are prescribed herbs, Yin Er is something a family eats in dry autumn weather. It is neutral rather than cold, which makes it easier to tolerate than the colder yin tonics, and its Lung-and-Stomach focus is narrower than the Kidney-directed yin tonics. Its bland flavour and gentle nature mean it is more often a supporting or dietary member of a strategy than the herb that carries it.

  Source: our own herb record alternate names (Bai Mu Er, Bai Yin Er), notes field (Long Yan Rou, Lian Zi, rock sugar), properties and category; Auricularia distinguished as a separate fungus in the food-safety literature (PMID 36630445, PMC 9833544); comparisons cross-referenced against multiple online sources and published materia medica consensus.