Chaga
Chaga (Inonotus obliquus) is a black, crusty fungus that grows on birch trees and is brewed into tea. The claims about it come from cell and animal studies; what is known in people is mostly a safety warning about oxalate and the kidneys.
No set daily amount
High in oxalate, which can damage the kidneys in large amounts
0 large trials in people; the evidence is from cells and animals
- Grows on Birch trees in cold northern forests
- How it is taken Tea also powders and extracts
- Studied compounds Betulinic acid, polysaccharides in lab studies only
- Main risk Kidney damage from oxalate, with heavy use
From published reviews and case reports. No food figures: chaga is not a food.
Chaga Tea and Supplements
Food supplies none. Chaga is too hard to eat, so it is brewed or bought as a supplement.
- Chaga teachunks or coarse powder steeped in hot water, a folk remedy in Russia and northern Europe for centuries; it brews dark and tastes earthy
- Supplementscapsules, fine powders and liquid extracts, made from wild-harvested chaga or from mycelium grown on grain; the amount of any compound is rarely stated
What Is Chaga?
Chaga does not look like a typical mushroom. The part that is harvested is a sterile conk: a hard lump of fungal tissue that bursts through the bark of a living birch. Its outside is black and cracked like burnt charcoal; inside it is rusty orange and corky. It does not make spores, and it slowly kills the tree it grows on.
Chaga Health Claims and the Evidence
Chaga is sold for immunity, blood sugar, and cancer. Those claims come from cell cultures and animals: chaga extracts slowed tumor cells in lab dishes, lowered blood sugar in diabetic mice and acted as antioxidants in test tubes. Betulinic acid, which chaga draws from the birch bark, is one compound studied for this. None of this has been shown in clinical trials in people.
Chaga, Oxalate, and Kidney Damage
Oxalate is a natural compound that binds calcium. In the kidneys, too much of it forms calcium oxalate crystals, the material of the most common kidney stones. Chaga powder has been measured with very high oxalate levels.
The clearest warning is a case reported from Japan in 2014. A 72-year-old woman with liver cancer took 4 to 5 teaspoons of chaga powder a day for 6 months, hoping it would help. She developed kidney failure, and a biopsy showed her kidneys clogged with oxalate crystals. Oxalate is also why calcium matters here: calcium eaten in the same meal binds some oxalate in the gut, one reason people prone to stones are usually told not to cut calcium.
Who Should Be Careful With Chaga
- Kidney disease or kidney stonesthe oxalate load is the main known risk
- Diabetes medicinesanimal studies suggest it lowers blood sugar, which could add to their effect
- Blood thinnerslab studies suggest it may slow clotting; ask a doctor first
Of the mushrooms sold as teas and extracts, reishi and turkey tail have at least been tested in human trials.
Sources are listed at the end of this page. Not medical advice.
Tracking Chaga in Caltide
- Not totaled yetCaltide does not add up chaga or the oxalate in it. Plain chaga tea adds almost no calories; edible mushrooms are in the food library with their full breakdown.
Related Nutrients
Chaga Sources and References
The figures and claims on this page are checked against these sources.
Questions About Chaga
Chaga (Inonotus obliquus) is a fungus that grows on birch trees in cold northern forests. What people harvest is a black, cracked, charcoal-like growth on the trunk with a rusty orange inside, not a mushroom with a cap.
Barely. Claims about cancer, blood sugar, and immunity come from cell and animal studies; there are no large human trials showing that chaga prevents or treats any disease.
Yes, in large amounts. Chaga is very high in oxalate, and a woman in Japan developed kidney failure from oxalate deposits after taking 4 to 5 teaspoons of chaga powder a day for 6 months.
People with kidney disease or a history of kidney stones, because of the oxalate. Lab and animal studies also suggest it may lower blood sugar and slow clotting, so people on diabetes drugs or blood thinners should ask a doctor first.
Mostly as a tea brewed from chunks or ground powder, a use that goes back to folk medicine in Russia, and as capsules or extracts. It is too hard to eat as food.
Partly. Both are sold as teas and extracts, but the part harvested as chaga is a sterile mass of fungus that does not make spores, while reishi is a true fruiting body. Neither has strong evidence in people.
Not yet. Caltide does not total chaga compounds or oxalate, and plain chaga tea adds almost no calories.
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