Proof Engine Verification: Frequent sauna use 4 to 7 times per week dramatically lowers risk of heart disease, dementia, and all-cause mortality.

Automated fact-verification of the claim: "Frequent sauna use 4 to 7 times per week dramatically lowers risk of heart disease, dementia, and all-cause mortality." Verdict: PARTIALLY VERIFIED Key Findings Heart disease (SC1 — HOLDS): Three independent peer-reviewed sources confirm the association. Laukkanen et al. 2015 (JAMA Internal Medicine) found sudden cardiac death hazard ratio (HR) 0.37 (95% CI 0.18–0.75) for 4–7 sauna sessions/week vs 1/week — a 63% reduction. Laukkanen et al. 2018 (BMC Medicine) found fatal CVD HR 0.30 (95% CI 0.14–0.64) — a 70% reduction. A 2018 Mayo Clinic Proceedings systematic review independently confirms the cardiovascular benefit. Dementia (SC2 — HOLDS): Laukkanen et al. 2017 (Age and Ageing) found dementia HR 0.34 (95% CI 0.16–0.71) for 4–7 sessions/week vs 1/week — a 66% reduction. ScienceDaily independently reported the same finding. All-cause mortality (SC3 — HOLDS): Laukkanen et al. 2015 reported raw all-cause mortality of 49.1% (1×/week) vs 30.8% (4–7×/week), a 37% relative reduction. Harvard Health Publishing independently corroborated these percentages. Causation (SC4 — DOES NOT HOLD): The claim uses causal language ("lowers risk"), requiring a separate causation sub-claim. No RCTs with mortality endpoints exist for sauna use. A 2025 systematic review of RCTs (Hamaya et al.) found passive heating "may not improve most of the cardiometabolic or vascular health markers," and a 2023 RCT in coronary artery disease patients found no change in vascular function. Confounding by healthy lifestyle remains unresolved. Files proof.py — Re-runnable Python verification script proof.md — Structured proof report proof_audit.md — Full verification audit trail proof_narrative.md — Plain-language summary proof.json — Machine-readable structured data Generated by Proof Engine v1.3.1.