Ashwagandha for Depression
Ashwagandha shows only weak, inconsistent evidence for depression: a handful of low-quality trials hint at benefit, but the signal comes mostly from anxiety and stress populations rather than clinical depression, and major clinics say it has not been adequately studied for this use. It is not a substitute for established depression treatments.
Why this grade7-layer evidence engine
The grade reflects thin, low-quality human data specific to major depressive disorder. A 2025 systematic review (PMID 41140145, ~713 participants) found a frequentist effect favoring ashwagandha on depression scales, but the result lost statistical significance under a more conservative Bayesian analysis, with extreme heterogeneity (I2 = 93%). A 2024 meta-analysis (PMID 39348746) reported an implausibly large effect (SMD -5.68) that likely reflects a scale-mixing artifact rather than a true benefit. Two narrative reviews (PMID 34254920, PMID 35139495) only suggest possible antidepressant mechanisms without any quantitative synthesis.
Most of the positive signal is extrapolated from anxiety and stress studies, not primary depression. The single supportive double-blind RCT (PMID 37878284, n=70) was industry-funded, raising a conflict-of-interest concern; the median trial duration was only about 8 weeks, whereas depression effects usually need 12 or more weeks to judge; and there are no head-to-head comparisons against SSRIs or other standard antidepressants.
Authoritative bodies are cautious or silent on depression specifically. Mayo Clinic states it 'has not been well studied in depression,' Cleveland Clinic calls the mental-health evidence 'unclear,' and the NIH Office of Dietary Supplements notes possible effects on stress, anxiety, and cortisol but does not address depression. The WHO lists it only as a traditional-use plant, and psychiatric societies and Harvard Health take no position, which together support a weak, warning-tier 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 = 0.582
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高階證據未達主導 (1 positive vs 1 negative)，由 raw_score 決定
- 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 0 個 hard + 1 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status