Atlas chapter 25 · Safety signal

Chaga

Inonotus obliquus

E1unresolved — Not assignable / unresolvedR0-1

Proposition / claim: Major advertised therapeutic claims lack mature direct human validation
Evidence owner: No mature human therapeutic evidence owner; the safety signal belongs to specific commercial preparations
Dominant uncertainty: Therapeutic: human translatability. Safety: preparation-specific oxalate exposure and risk quantification.

Organism: Chaga
Tested intervention: No single qualifying human therapeutic intervention. Therapeutic literature discussed in the dossier includes heterogeneous preclinical Inonotus obliquus extracts and preparations. The human safety signal belongs to specific substantial Chaga exposures, particularly powder preparations reported in oxalate nephropathy cases. Therapeutic and safety interventions are kept separate.
Evidence target: THERAPEUTIC_SAFETY_SPLIT: heterogeneous preclinical Chaga preparations / exposure-specific commercial Chaga preparations associated with the human renal hazard signal. A single standardized-preparation target would falsely imply intervention equivalence, because the dossier evaluates (1) broad therapeutic claims resting principally on heterogeneous preclinical preparations and (2) an exposure-specific human safety signal belonging to particular Chaga preparations.
Intervention description: THERAPEUTIC: heterogeneous Chaga preparations including powders, tea/decoction, extracts, concentrates and commercial products; no mature qualifying direct human therapeutic intervention identified for the major advertised cancer/immune/longevity claims. SAFETY: specific real-world Chaga preparations consumed at substantial exposure in published renal case reports. One particularly informative 2020 case included chemical analysis of the consumed Chaga powder and of comparison commercial powders. Preparation identity is part of the safety proposition.
Population: THERAPEUTIC: no qualifying mature direct human therapeutic population identified for the major advertised cancer, immune, longevity or broad disease-prevention claims. SAFETY: individual patients described in published human renal case reports following substantial Chaga exposure. Safety case-report populations are not converted into an efficacy population.
Comparator: THERAPEUTIC: no qualifying mature human therapeutic comparator identified for the major advertised claims. SAFETY: not applicable as an efficacy comparator; human hazard evidence derives from clinical case reports with exposure histories, renal pathology and, in the particularly informative 2020 case, analysis of the consumed Chaga material. No randomized safety comparison is implied.
Outcome: THERAPEUTIC: No mature qualifying direct human evidence establishing the major advertised therapeutic outcomes — cancer treatment or prevention, general immune enhancement, longevity, or broad disease prevention. Extensive preclinical biological activity does not constitute human therapeutic efficacy. SAFETY: Published human cases describe serious kidney injury with renal biopsy findings consistent with oxalate nephropathy after substantial Chaga exposure. In the particularly informative 2020 case the consumed Chaga powder contained approximately 14.2 g oxalate/100 g, with two additional commercial Chaga powders at approximately 2.8 and 11.2 g/100 g. These findings support an exposure-specific HAZARD signal. They do not establish universal Chaga nephrotoxicity, risk at ordinary exposure, a universal toxic threshold, or equivalent risk across powder, tea, water extract, alcohol extract or concentrate. Hazard identification is not risk quantification.
Evidence maturity (E): E1
Direction: unresolved — Not assignable / unresolved
Historical flag (H): Not specified at dossier level
Replication (R): R0-1
Claim Gap (CG): CG1 for preclinical or safety-specific wording
Evidence Transfer Vector: X / I / P / O / D / R — for the expanded therapeutic claim "Chaga safely helps prevent cancer." X: preclinical experimental level → human prevention. I: defined laboratory extracts → generic Chaga product. P: animals/cells → healthy humans. O: biological activity → cancer prevention. D: laboratory exposure → ordinary supplementation. R: volume/repetition of preclinical research → assumed human certainty.
Taxonomic Transfer Confidence: HIGH relative to more difficult taxa
Intervention Transfer Confidence: LOW-VARIABLE across powder, tea and extract products
Safety: S3 — exposure-specific hazard signal for oxalate-associated renal injury
Conservation: C1-2 / C+
Resolution zone: Therapeutic RZ-4; safety RZ-1 / RZ-7
Next best experiment: Commercial Chaga oxalate/exposure map
Primary references: Kikuchi Y, et al. Chaga mushroom-induced oxalate nephropathy. Clinical Nephrology. 2014;81(6):440-444. PMID 23149251. — Human safety case; oxalate nephropathy hazard support; replication context. Hazard identification only; not usable for ordinary-use incidence, population risk or a universal toxic dose; not therapeutic evidence.
Lee HY, et al. Development of End Stage Renal Disease after Long-Term Ingestion of Chaga Mushroom: Case Report and Review of Literature. Journal of Korean Medical Science. 2020;35:e122. PMID 32419395. PMCID PMC7234858. — Principal human safety evidence owner; exposure history + renal pathology + chemical analysis of the consumed material in one report. Consumed Chaga powder approximately 14.2 g/100 g oxalate; two comparison commercial powders approximately 2.8 g/100 g and approximately 11.2 g/100 g, supporting preparation/product variability as a central safety question. Supports S3 exposure-specific hazard signal; does not establish universal nephrotoxicity, ordinary-use risk, a universal toxic threshold, or equivalence across tea, powder, water extract, alcohol extract or concentrate.
Kwon O, Kim Y, Paek JH, Park WY, Han S, Sin H, Jin K. Chaga mushroom-induced oxalate nephropathy that clinically manifested as nephrotic syndrome: A case report. Medicine (Baltimore). 2022;101(10):e28997. DOI 10.1097/MD.0000000000028997. PMID 35451393. PMCID PMC8913114. — Human safety case; co-exposure boundary; causal-interpretation context. Approximately 10-15 g/day Chaga powder plus 500 mg/day vitamin C for approximately three months; renal pathology included tubular injury and calcium oxalate deposition. Vitamin C is a relevant potential contributor to oxalate burden, so this is supportive human hazard evidence but not a clean Chaga-only causal observation.
Lee S, Cui S, Fang X, et al. Kidney Injury Induced by High-Dose Chaga Mushroom Consumption: Experimental Evidence in a Rat Model. Journal of Korean Medical Science. 2026;41(3):e37. DOI 10.3346/jkms.2026.41.e37. PMID 41555803. — Animal mechanistic evidence; renal hazard coherence only; not human-grade evidence. Renal oxalate deposition and tubular injury after high-dose exposure, not reported equivalently in control or standard-dose conditions. Does not create a human case, quantify ordinary human risk, establish a human toxic threshold, or upgrade S3.
Tee Yon Ern P, Tang YQ, Fung SY, Chia YY. Therapeutic properties of Inonotus obliquus (Chaga mushroom): A review. Mycology. 2023;15(2):144-161. DOI 10.1080/21501203.2023.2260408. PMID 38813471. PMCID PMC11132974. — Therapeutic-literature review; preclinical-human boundary; E1 context. Documents the breadth and predominantly preclinical character (in-vitro, isolated compounds, cell and animal models, mechanistic work) of the therapeutic research programme. The review authors' stronger therapeutic language is not adopted as demonstrated human clinical efficacy; extensive preclinical literature is not human therapeutic replication; the review is not used to claim that no human study of Chaga has ever existed.
Source chapter: Chapter 25, The Fungal Evidence Atlas