Educational information, not medical advice — ask your doctor or midwife.
Auricularia auricula-judae is an edible mushroom, sold mostly dried as wood ear, black fungus or mu-er. It swells into a soft, ear-shaped jelly when soaked. In most homes it is a food first and a remedy second.
One safety point comes before anything else. Dried wood ear must never be left soaking for many hours in warm water on the counter. Rare but deadly poisonings have followed long soaks, caused by a bacterial toxin that grows in the wet fungus.
Chinese food and medicine traditions valued it for the blood and the lungs. European folk use gave it the name Judas's ear.
Long use in cooking shows it is a familiar food. It does not prove a health benefit, and it does not prove that concentrated extracts are safe.
The short evidence verdict: human trials are very thin. Most of what is said about its effects comes from lab and animal work, plus a few old case reports.
No mechanism for wood ear has been confirmed in people. The ideas below come from the lab bench, not the clinic.
The fungus is rich in soluble fibre and beta-glucans. In test tubes and in animals, these gels bind bile acids and slow sugar uptake. That is the usual reason given for claims about cholesterol and blood sugar.
In laboratory tests, extracts appear to slow the clumping of platelets, the cells that start a clot. An older clinical report described the same effect in people who ate large amounts. This is the one area where a real human signal exists, and it reads as a risk as much as a benefit.
Animal studies also report lower blood fats and some effect on gut bacteria. Whether any of this happens at normal food amounts in humans is not established.
Most people meet it as food. Supplement forms exist but are far less studied.
- Dried whole or sliced fungus, the standard grocery form, soaked before cooking. - Fresh fungus, sold in some Asian markets.
- Powder, made from dried milled fruiting bodies. - Capsules and tablets of powder or hot-water extract. - Liquid extracts and tinctures, less common.
Blended "mushroom complex" products often list it with reishi, shiitake or maitake. In those blends the amount of wood ear is usually small.
Chinese cooking and medicine have used wood ear for well over a thousand years. Classical texts grouped it with foods said to nourish the blood and moisten the lungs. It was eaten as part of meals far more often than taken as a drug.
In Europe the fungus was called Judas's ear, from a legend about the tree where Judas died. Folk use included soaking it and using the liquid as a gargle for sore throat, or as a wash for sore eyes.
These accounts are records of custom. They were not written to test whether the fungus worked, and none of them should be read as a reason to self-treat today.
Get emergency care if you feel sick, vomit, have belly pain, sweat heavily, feel confused or very drowsy within a day of eating soaked wood ear. These can be signs of serious poisoning and it can get worse fast. Take the food with you if you can.
See a doctor soon if you notice easy bruising, bleeding gums, nosebleeds, or blood in your stool or urine. Stop supplements first.
Get urgent help for swelling of the lips or tongue, a spreading rash, or trouble breathing after eating it.
In the US, UK and EU it is an ordinary food, sold freely in groceries. Capsules and extracts are sold as food supplements, not as licensed medicines, so they may not claim to treat disease.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
What it is typically used for, usual dose, cautions, and the study behind it where real trial data exists.
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