Pyrroloquinoline Quinone (PQQ) for Cognitive Function
PQQ is not proven to improve cognitive function. The only supporting human trials are small and were all funded by PQQ manufacturers, while regulators have cleared it for safety only and dementia specialists say no supplement has been shown to benefit brain health.
Why this grade7-layer evidence engine
This grade reflects a thin, conflicted evidence base. Four small randomized trials all point in PQQ's favor: Itoh 2016 (n=41) found a smaller Stroop interference ratio at 20 mg/day over 12 weeks (PMID 26782228); Shiojima 2022 (n=64) reported gains in memory, attention, and executive function at 21.5 mg/day (PMID 34415830); a 2023 Food & Function trial (n=62) showed improved composite and verbal memory; and a 2024 trial in mild cognitive impairment (n=34) found higher BDNF and cerebral oxygenation (PMID 38908296). But every one of these was industry-funded, none exceeded ~64 participants, and no independent or pooled meta-analysis exists.
The dispute flag is driven by the gap between these manufacturer trials and authoritative bodies. The Alzheimer's Association states plainly that 'not a single food, beverage, ingredient, vitamin or supplement has been proven to prevent, treat or cure Alzheimer's disease or to benefit cognitive function or brain health.' Mayo Clinic, Cleveland Clinic, Harvard Health, and the NIH Office of Dietary Supplements are silent on PQQ for cognition, and Examine.com has no cognitive entry for it.
Regulators add no efficacy support: the FDA's GRAS notices, EFSA, and WHO-cited assessments deem PQQ disodium salt safe up to 20 mg/day for healthy adults but authorize no health claims, and they explicitly exclude pregnant or breastfeeding women and those under 15. With 100% industry funding, small samples, and no specialty-society endorsement, the consistent-but-unverified signal earns only a weak, disputed rating rather than a positive verdict.
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditable▸View the full decision path (audit trail)
- compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.503
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 無高階證據可裁決
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 1 個 hard + 1 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status