Rhodiola Rosea for Cognitive Function
Rhodiola rosea has only weak, disputed evidence for cognitive function: a handful of small, dated trials hint at better mental performance, but the effect appears driven by reduced fatigue rather than any direct brain-boosting action, and no major health body endorses it for cognition.
Why this grade7-layer evidence engine
The grade is C (Weak Evidence) because the human trials are few, small, and old. The cognitive signals come almost entirely from anti-fatigue studies in which mental performance was a secondary outcome: night-duty physicians (PMID 11081987), exam-stressed students (PMID 10839209, a pilot), and military cadets (PMID 12725561). A 2011 systematic review (PMID 21036578) judged the effect on mental performance plausible but explicitly flagged a lack of independent replication, and there is no cognition-specific RCT or meta-analysis since 2020.
It is marked Disputed because the apparent benefit is likely fatigue-mediated rather than a true nootropic effect, and one supportive trial (PMID 20374974) tested ADAPT-232, a multi-herb combination, so its attention gains cannot be credited to rhodiola alone. Several trials used the proprietary SHR-5 extract with undisclosed funding, weakening confidence further.
Regulators and clinicians reinforce the cautious read. The UK registers rhodiola only as a traditional herbal product for stress and fatigue based on traditional use, not proven efficacy, and the US FDA has issued warning letters over disease claims. Mayo Clinic and Harvard Health publish nothing supporting rhodiola for memory, and the Alzheimer's Association states that no supplement has been proven to benefit cognitive function or brain health.
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 = 0.562
- 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 — | B→C 因 scope.conflation_risk=true 且 L11 獨評較低 (B7-2 tier cap)
- detect_disputes — 偵測到 1 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status