Educational information, not medical advice — ask your doctor or midwife.
Birch polypore is a bracket fungus that grows on birch trees. It forms a pale, smooth, hoof-shaped shelf on dying or dead trunks. Its current name is Fomitopsis betulina, once called Piptoporus betulinus.
In the North it is known as knivkjuke, björkticka and pökkelökääpä. Country people used it as tinder, as a strip for honing knives, and as a wound cover. Today it is sold mainly as a dried tea, a powder or capsules.
Here is the honest verdict. Almost no human trials exist, so claims about health effects rest on test tube and animal work. Long traditional use is not proof that it works, and it is not proof that it is safe.
Nobody has shown what birch polypore does inside the human body. The lab work gives hints, and nothing more.
In test tubes, extracts slow the growth of some bacteria, fungi and viruses. In cell and animal studies, some of its compounds lower markers of swelling. Whether any of that happens when you drink a cup of the tea is unknown.
Beta-glucans are fibre-like sugars found in many mushrooms. In lab dishes they stir immune cells into action. That is a dish finding, not a proven effect in people.
Betulinic acid has killed cancer cells in dishes and slowed tumours in mice. No human trial supports using the mushroom for cancer. Please do not treat it as cancer care.
The old use as a wound dressing may owe as much to the material as to the chemistry. The flesh is soft, dry and fairly clean when freshly cut. That makes it a decent pad, which says little about healing power.
Most products are dried and ground, then sold as a tea or in capsules.
- Dried slices or chips, simmered in water to make a bitter tea. - Powder, stirred into hot water or a drink. - Capsules holding plain powder.
- Liquid extracts made with alcohol, water, or both. - Dual extracts, which use hot water and alcohol in turn. - Whole dried brackets sold to foragers and craft users.
The raw flesh is tough, corky and very bitter. It is not a food mushroom, and people do not fry or eat it like a chanterelle.
Quality control is weak across this market. Labels rarely state how much of any compound is present. Some products mix several mushrooms in one blend, so check the full list before you buy.
Birch polypore has a long record of practical use across northern Europe. In Scandinavia it was cut into strips and used to hone knives and razors. Dried pieces also served as tinder for fire-making.
People laid thin slices on cuts and grazes as a simple dressing. Some accounts describe a bitter tea taken for stomach trouble or tiredness.
Two pieces of the fungus were found with Ötzi, the 5,300-year-old iceman from the Alps. Writers often call this proof of medicinal use. In truth, the reason he carried it is still argued over.
None of this history tells you that the fungus treats any illness. It tells you that it was useful, close to hand, and widely known.
Stop and get medical help straight away if you get a rash, wheezing, or swelling of the lips, tongue or face.
See a doctor if you have vomiting, bad stomach pain, or yellow skin or eyes.
Also book an appointment if a wound turns red, hot or swollen, or if tiredness, weight loss or bowel changes last more than two weeks.
In the UK, the EU and the US it is sold as a food supplement, not as a medicine. No health claim for it has been approved in those markets.
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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