NutriDex

The Supplement Research Compendium
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Chaga

Inonotus obliquus

Antioxidant birch fungus with bold claims but no human efficacy trials.

Preliminary evidence 🛡️Gut & Immune⏳Longevity

✚ Updated · How we grade evidence

Evidence tier
Preliminary
Research weight
Citations
6 verified / 6
Classification
Gut & Immune
❝
What the evidence says. Graded preliminary: chaga has rich antioxidant chemistry and promising mouse, rat and cell data, but there are essentially no controlled human efficacy trials. The only human evidence is ex-vivo lymphocyte assays, while real-world reports document serious kidney harm from its high oxalate content. (Preliminary evidence: Early or small human trials; promising but not yet conclusive.)

What is Chaga?

Chaga (Inonotus obliquus) is a gut and immune supplement used for antioxidant support. NutriDex grades the human evidence as Preliminary. Chaga is a parasitic fungus that grows on birch trees and is sold as a powder, tea or extract for immunity, anti-aging and blood sugar. Its appeal rests on genuinely high levels of antioxidants, beta-glucans and triterpenoids. However, the evidence base is almost entirely preclinical: anti-diabetic, anti-inflammatory and anti-fatigue effects have been shown only in mice, rats and cell cultures. The strongest human-derived data come from ex-vivo experiments where chaga extract reduced hydrogen-peroxide-induced DNA damage in donated lymphocytes (about 35–55%), which does not establish any clinical benefit. No randomized controlled trials in people support the marketed claims. Meanwhile, chaga is extremely high in oxalate (up to ~14 g per 100 g), and multiple case reports link long-term or high-dose use to acute oxalate nephropathy and even end-stage kidney disease. Benefit in humans is unproven; the documented risk is concrete.

Purported Benefits

✓Antioxidant support
✓Immune modulation
✓Anti-inflammatory (claimed)
✓Blood-sugar support (claimed)

Evidence by outcome

The same supplement can be well-proven for one use and unproven for another — here is the human evidence graded outcome by outcome.

OutcomeEvidenceEffectStudies
Antioxidant / DNA-damage protectionOnly ex-vivo lymphocyte assays show reduced H2O2-induced DNA damage (~35-55%); not a clinical outcome. Preliminary ↑ benefit 2
Immune modulation, anti-inflammatory & blood-sugar (claimed)All claimed metabolic/immune effects are preclinical (animal/in-vitro); no human RCTs support marketed claims. No Evidence — no effect

Dosing & Compounds

Typical Dose
No established human dose; products supply ~1–3 g/day of dried sclerotium or extract, but safe long-term dosing is undefined.
Active Compounds
Beta-glucan polysaccharidesTriterpenoids (e.g. betulinic acid)Polyphenols & melaninSuperoxide dismutase

Safety & Cautions

Chaga is very high in oxalate (up to ~14 g per 100 g), and case reports tie prolonged or high-dose use to acute oxalate nephropathy and end-stage kidney disease, especially when combined with vitamin C or in those with kidney disease, diabetes or dehydration. It may lower blood sugar and could add to antidiabetic drugs, and its claimed antiplatelet/blood-thinning activity raises a theoretical bleeding risk with anticoagulants such as warfarin. Avoid in pregnancy, breastfeeding, kidney stones or chronic kidney disease, and before surgery; quality and oxalate content of wild-harvested products are unregulated. Educational only — always check with your doctor or pharmacist before combining Chaga with any medicine.

Chaga drug interactions

Known or theoretical interactions between Chaga and common medications — educational, not exhaustive. Always check with your doctor or pharmacist before combining Chaga with any medicine.

Caution
Blood thinners (warfarin, DOACs)
Chaga may add to bleeding risk when combined with blood thinners.
Chaga (Inonotus obliquus) contains a platelet-aggregation-inhibiting peptide that can compound anticoagulants. Platelet aggregation inhibitor from Inonotus obliquus (PubMed)
Caution
Antiplatelet drugs (aspirin, clopidogrel)
Chaga with aspirin or clopidogrel may increase bleeding tendency.
A chaga-derived peptide inhibits platelet aggregation, adding to antiplatelet drugs. Platelet aggregation inhibitor from Inonotus obliquus (PubMed)

Key Studies

Safety Kwon 2022 ✓ PubMed
69-y-old man on chaga 10–15 g/day for 3 months developed acute oxalate nephropathy presenting as nephrotic syndrome.
Safety Lee 2020 ✓ Full text
49-y-old developed end-stage renal disease after 5 years of chaga; sample contained 14.2 g oxalate/100 g, biopsy showed oxalate crystals.
RCT Park 2004 ✓ PubMed
Chaga extract cut H2O2-induced oxidative DNA damage in human lymphocytes by over 40% (comet assay); ex-vivo, not a clinical trial.
RCT Najafzadeh 2007 ✓ PubMed
Ex-vivo chaga extract reduced H2O2-induced DNA damage 54.9% in IBD-patient lymphocytes and 34.9% in healthy controls (n=20+20).
Review Aladejana 2024 (review) ✓ Full text
Therapeutic-properties review concludes mechanisms remain poorly understood and human clinical evidence is essentially absent.
Review Lu 2021 (review) ✓ Full text
Review: chaga polysaccharides show immune, anti-fatigue and anti-diabetic activity in vitro and in animals; no human trials cited.
6 sources cited · 6 verified Search all studies on PubMed ↗

Common questions about Chaga

What is Chaga used for?

Chaga is most often taken for Antioxidant support, Immune modulation, Anti-inflammatory (claimed), Blood-sugar support (claimed). Antioxidant birch fungus with bold claims but no human efficacy trials.

Does Chaga work — what does the evidence say?

Preliminary evidence. Early or small human trials; promising but not yet conclusive. Chaga is a parasitic fungus that grows on birch trees and is sold as a powder, tea or extract for immunity, anti-aging and blood sugar. Its appeal rests on genuinely high levels of antioxidants, beta-glucans and triterpenoids. However, the evidence base is almost entirely preclinical: anti-diabetic, anti-inflammatory and anti-fatigue effects have been shown only in mice, rats and cell cultures. The strongest human-derived data come from ex-vivo experiments where chaga extract reduced hydrogen-peroxide-induced DNA damage in donated lymphocytes (about 35–55%), which does not establish any clinical benefit. No randomized controlled trials in people support the marketed claims. Meanwhile, chaga is extremely high in oxalate (up to ~14 g per 100 g), and multiple case reports link long-term or high-dose use to acute oxalate nephropathy and even end-stage kidney disease. Benefit in humans is unproven; the documented risk is concrete.

What is the typical dose of Chaga?

No established human dose; products supply ~1–3 g/day of dried sclerotium or extract, but safe long-term dosing is undefined.

Is Chaga safe? Any cautions or side effects?

Chaga is very high in oxalate (up to ~14 g per 100 g), and case reports tie prolonged or high-dose use to acute oxalate nephropathy and end-stage kidney disease, especially when combined with vitamin C or in those with kidney disease, diabetes or dehydration. It may lower blood sugar and could add to antidiabetic drugs, and its claimed antiplatelet/blood-thinning activity raises a theoretical bleeding risk with anticoagulants such as warfarin. Avoid in pregnancy, breastfeeding, kidney stones or chronic kidney disease, and before surgery; quality and oxalate content of wild-harvested products are unregulated.

How many studies support Chaga?

NutriDex cites 6 sources for Chaga, graded "Preliminary".

Does Chaga interact with any medications?

Yes — known or theoretical interactions include: Blood thinners (warfarin, DOACs) (caution), Antiplatelet drugs (aspirin, clopidogrel) (caution). This is educational and not exhaustive; always check with your doctor or pharmacist before combining Chaga with any medicine.

Cite this page
APA

Peh, D. (2026). Chaga (Inonotus obliquus): Benefits, Dosage, Side Effects & Evidence. NutriDex — The Supplement Research Compendium. Retrieved 26 Jun 2026, from https://nutridex.info/s/chaga

BibTeX
@misc{nutridex_chaga,
  author       = {Peh, Daryl},
  title        = {Chaga (Inonotus obliquus): Benefits, Dosage, Side Effects \& Evidence},
  year         = {2026},
  howpublished = {NutriDex --- The Supplement Research Compendium},
  url          = {https://nutridex.info/s/chaga},
  note         = {Reviewed by Dr Daryl Peh, MBBS Singapore, MMed FM. Accessed 2026-06-26}
}

For medical claims, citing the underlying primary studies linked above is preferred. NutriDex is an educational reference, not medical advice.

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