Chaga (Inonotus obliquus)
Also known as: Inonotus obliquus, chaga mushroom, birch conk, clinker polypore, chaga sclerotium
Chaga is not a true fruiting body but a sclerotium, a dense black mass that grows on birch trees. It is rich in melanin pigments, betulinic acid derived from birch bark, and beta-glucans, and is marketed for antioxidant and immune support. Human clinical data are almost entirely lacking; the evidence is in vitro and animal work, plus case reports of oxalate-related kidney injury after long-term heavy intake of chaga powder. Wild-harvested chaga is high in oxalate, so extracts should be dosed conservatively and sourced from suppliers that test for oxalate and heavy metals.
Research summary
Melanin and polyphenols are studied for radical scavenging activity; beta-glucans are studied for immune cell receptor activation. Mechanistic data are largely preclinical.
Dosage
Daily amounts, of extract.
| Lowest studied | Typical range | Highest studied | Upper limit |
|---|---|---|---|
| — | 500–1,500 mg | — | — |
The 500–1,500 mg range reflects market practice for a hot-water extract, not clinical trials. Keep daily intake modest and avoid stacking with other high-oxalate ingredients; published case reports involved months of daily chaga powder in the multi-gram range. Not recommended for people with a history of kidney stones.
Standardization: ≥10% beta-glucans (hot-water extract); oxalate and heavy metals tested
Source material: sclerotium (wild-harvested conk, sold as the fruiting body)
Format suitability
- Capsule
- Powder
- Tablet
- Softgel
- Gummy
- Liquid
Dark, earthy; discolors light-colored powders. Extract is preferred over raw ground chaga to limit oxalate.
Formulation notes
High oxalate content; avoid combining with other oxalate-rich ingredients and flag for users with a kidney stone history. Chaga has been reported to interact with anticoagulant and blood-sugar-lowering drugs.
- Notable drug interactions
Sources
- Preparation, bioactivities, structure-activity relationships, applications, and safety concerns of Inonotus obliquus polysaccharides: A review. (Cui 2026)PubMed
- Chaga mushroom-induced oxalate nephropathy that clinically manifested as nephrotic syndrome: A case report. (Kwon 2022)PubMed
- Development of End Stage Renal Disease after Long-Term Ingestion of Chaga Mushroom: Case Report and Review of Literature. (Lee 2020)PubMed
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