Pyrroloquinoline Quinone (PQQ) for Fatigue
There is no reliable human evidence that pyrroloquinoline quinone (PQQ) reduces fatigue: the only trial measuring fatigue directly was tiny, uncontrolled, and industry-run, while the better-designed studies either didn't measure fatigue at all or found no benefit. Regulators clear PQQ as safe at low doses but endorse no anti-fatigue claim.
Why this grade7-layer evidence engine
This rates Unverified (Disputed) because the evidence base for fatigue is essentially one weak study. The sole trial with a fatigue endpoint (Nakano 2012, n=17) was open-label with no placebo arm and funded by the BioPQQ manufacturer, so its improvements cannot be separated from expectancy and regression to the mean. A 2024 manufacturer-authored review (PMID 38735721) adds no new fatigue data and simply recycles that same study, creating an echo chamber rather than confirmation.
The stronger trials do not rescue the claim. The two double-blind RCTs (PMID 26782228, n=41; PMID 38908296, n=34) tested cognition and brain biomarkers, not fatigue. More tellingly, the one placebo-controlled exercise trial (Hwang 2020, PMID 31860387, n=23) found PQQ did not improve aerobic performance, a direct negative signal for energy claims. Benefit on fatigue itself comes only from a mouse swimming study (PMID 33710654), which is mechanistic and does not translate to people.
Regulatory clearances are about safety, not efficacy: the FDA (GRAS), EFSA, UK FSA, and WHO authorize PQQ as a food supplement at up to 20 mg/day for healthy adults (excluding pregnant and lactating women) but approve no health claim. Major clinical bodies (NIH ODS, Mayo, Cleveland Clinic, Harvard) are silent. With heavy affiliate marketing and theoretical drug interactions flagged, the honest verdict is that PQQ has not been demonstrated to relieve fatigue.
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 = 0.387
- 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 — | D→U 因 scope.conflation_risk=true 且 L11 獨評較低 (B7-2 tier cap)
- detect_disputes — 偵測到 1 個 hard + 1 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status