Chaga (Birch Canker)
A hard, black growth found on birch trunks, traditionally brewed as a tea in Russia and Eastern Europe — today studied mainly for its exceptionally high content of antioxidant compounds.
Number of studies
1
Safety
Moderate
Time to effects
There is no solid clinical data to precisely determine the time to onset of effects in humans.
Who it's for
Table of contents
TL;DR
A hard, black growth found on birch trunks, traditionally brewed as a tea in Russia and Eastern Europe — today studied mainly for its exceptionally high content of antioxidant compounds.
- →Shows one of the highest measured antioxidant activities among the mushrooms studied
- →Contains beta-glucans that support innate immune cell activity in laboratory studies
- →A traditionally used tea with a mild, earthy flavor
| Latin name | Inonotus obliquus |
|---|---|
| Form | Sclerotium (a compact mass of mycelium), not a typical fruiting body |
| Research level | Early — mainly in vitro and animal studies |
| Distinctive component | Very high content of melanin and betulinic acid |
| Important limitation | High oxalate content — caution advised for those predisposed to kidney stones |
| Status | Traditional tea, dietary supplement |
Understand
Overview
Chaga (Inonotus obliquus) is a parasitic fungus that forms characteristic hard, black growths on the trunks of living birch trees, from which for centuries in Russia, Belarus, and the Baltic states a tea has been brewed and consumed as a traditional tonic. Unlike many other mushrooms described in this knowledge base, chaga is not a fruiting body in the usual sense, but a sclerotium — a compact mass of mycelium that forms in response to a wound in the tree.
This fungus stands out for its exceptionally high content of melanin and betulinic acid (obtained from the bark of the birch it parasitizes), which translates into one of the highest measured antioxidant activities among the mushrooms studied. However, the available studies remain mostly at the in vitro and animal-model stage — solid clinical trials in humans are still scarce.
Who can realistically benefit from this? People interested in traditional herbal teas with a high antioxidant content, who view chaga as part of a varied diet rather than a standalone therapeutic remedy. Because of its very high oxalate content, people with a history of kidney stones should exercise particular caution.
Mechanism of action
Chaga contains an exceptionally high concentration of melanin, which gives it its characteristic black color, and of triterpenes, including betulinic acid obtained from the metabolized bark of the birch tree the fungus parasitizes. In laboratory studies, these compounds show a strong ability to neutralize free radicals, which explains the interest in chaga as a source of natural antioxidants.
In addition, like many other mushrooms described in this knowledge base, chaga contains beta-glucans, which in animal-model studies are linked to a moderate activation of innate immune system cells via the dectin-1 receptor. It's worth noting, however, that chaga also contains a very high concentration of oxalates — compounds that can promote kidney stone formation in predisposed individuals — which sets its safety profile apart from that of many other mushrooms in this knowledge base.
High melanin content
Gives it its characteristic black color and a strong ability to neutralize free radicals.
Betulinic acid from birch bark
The fungus metabolizes compounds from its host tree's bark, enriching its triterpene profile.
Activation via beta-glucans
Like other medicinal mushrooms, chaga contains beta-glucans that activate innate immune cells.
Evidence: early-stage — based on 1 study in this database.
Benefits
Common myths
MythChaga is an ordinary mushroom that grows in the soil, similar to other edible mushrooms.
FactChaga is a sclerotium — a compact mass of mycelium that grows on the trunk of a living birch tree — biologically distinct from the typical fruiting body of a mushroom found on the forest floor.
MythChaga is completely safe for everyone because it's a natural product.
FactChaga's high oxalate content can promote kidney stone formation in predisposed individuals — an important, often overlooked safety limitation.
Forms & variants
Chaga (Birch Canker) comes in several forms that differ in bioavailability and use case — the form you pick genuinely matters for how effective the supplementation is.
Traditional tea
Dried chaga brewed as a tea, following Eastern European tradition.
Best for: Daily, moderate consumption
Standardized extract
A concentrated form with a defined content of active compounds.
Best for: More precise dosing
Practice
Frequently asked questions
Chaga stands out for its exceptionally high content of melanin and betulinic acid, which sets its profile apart from other medicinal mushrooms, despite sharing some mechanisms, such as beta-glucans.
Because of its high oxalate content, people with a history of kidney stones should exercise particular caution or avoid regular chaga consumption without consulting a doctor.
Dried, crushed chaga is covered with hot (not boiling) water and steeped for anywhere from several minutes to several hours, depending on the desired strength.
Dosage & timing
Typical dose
1–3 g of dried raw material or extract daily, traditionally brewed as a tea
Form
Dried sclerotium for brewing, powder, or standardized extract
Because of its high oxalate content, very high, prolonged doses are not recommended without consulting a doctor, especially for people with a history of kidney stones.
What to combine with
Good combinations
Beta-glucans — Beta-glucans are one of the key shared mechanisms linking chaga to other medicinal mushrooms in this knowledge base
Safety
Side effects & contraindications
Possible side effects
Possible interactions due to high oxalate content
Rarely: gastrointestinal discomfort with large amounts
Contraindications
History of kidney stones — high oxalate content
Blood clotting disorders or use of anticoagulant medication — caution advised
Interactions
Anticoagulants — theoretical interaction, requires caution
Immunosuppressant drugs — possible interaction due to the immunomodulatory effect of the beta-glucans
Is it worth taking?
Who it's for
- People interested in traditional teas with a high antioxidant content
Not for
- History of kidney stones — high oxalate content
- Blood clotting disorders or use of anticoagulant medication — caution advised
Evidence
Worth knowing
Chaga grows almost exclusively on living birch trees, from which it 'borrows' some of its compounds, including betulinic acid from the bark.
The traditional chaga tea has a long history of use in Russia, Belarus, and the Baltic states.
Studies
Extracts of Inonotus obliquus show one of the highest measured antioxidant activities among the mushrooms studied, though solid clinical trials in humans remain scarce.
Duru KC et al., pharmacological review of Inonotus obliquus, 2019
The pharmacological potential and possible molecular mechanisms of action of Inonotus obliquus from experimental observations
Early-stage evidenceDuru KC, Kovaleva EG, Danilova IG, van der Bijl P · Chemico-Biological Interactions · 2019
A review of laboratory and animal studies on the pharmacological properties of Inonotus obliquus, including its exceptionally high antioxidant activity.
View studySources & bibliography
Citations are illustrative for this demo version and require full bibliographic verification by the editorial team before production publication.
Compare with similar entries
About the authors of this entry
Author
dr Anna KowalczykEditor-in-Chief, Molecular Biology
Anna oversees the editorial process and scientific review of every publication in the knowledge base. She previously researched autophagy and mitochondrial biology.
50 publications on this site
Medical review
dr Piotr ZielińskiEndocrinologist
Piotr reviews content on hormones, metabolic health and supplement pharmacology.
131 publications on this site
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Comments (2)
- KW
Kasia W. 2 weeks ago
Very clearly explained, especially the interactions section — I hadn't seen it laid out this well anywhere else.
- MT
Marek T. a month ago
Are you planning to update this with the newest study from this year? I saw an interesting meta-analysis.