Chaste tree for Premenstrual Syndrome
A standardized chaste tree (Vitex agnus-castus) dry extract, taken at about 20 mg per day for three menstrual cycles, appears to reduce overall PMS symptoms in several trials, but the evidence is graded preliminary because the pivotal studies were industry-funded, statistically inconsistent, and short-term. It is not a substitute for first-line treatments, and the standardized extract studied is not the same as most over-the-counter whole-fruit products.
Why this grade7-layer evidence engine
The signal of benefit is real but limited. Two double-blind, placebo-controlled RCTs of standardized extracts found chaste tree superior to placebo: Schellenberg 2001 (n=170, Ze 440 20 mg/day) reported a 52% vs 24% improvement in symptom score (p<0.001; PMID 11159568), and He 2009 reproduced a significant benefit in 217 Chinese patients (BNO 1095; PMID 19269753). Reviews were directionally positive too — a 2017 systematic review found all 8 included PMS/PMDD trials positive for Vitex (PMID 29063202), and a separate 2017 meta-analysis pooling 14 trials found a large effect (Hedges' g ≈ -1.21, 95% CI -1.53 to -0.88; PMID 28237870).
The grade stays at preliminary, not higher, because that meta-analysis found very high heterogeneity (I² = 91%) and substantial risk of bias, the largest positive RCTs were funded by the extract manufacturers (Zeller, Bionorica), and trials ran only about 12 weeks, so longer-term efficacy is untested (PMID 28237870).
Authorities are split rather than convinced. The WHO lists PMS among uses supported by clinical data, but the US FDA has issued warning letters against products making PMS or fertility disease claims, and EFSA leaves food-supplement claims on hold. Mayo Clinic lists chasteberry while noting few herbs have proven effective, and specialty guidance calls for further study before recommending it. WHO also contraindicates use in pregnancy and breastfeeding, and the prolactin-lowering, dopaminergic mechanism raises potential interactions with hormonal contraceptives and dopamine drugs.
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 = 0.646
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高品質 SR/MA 顯示 positive (2 篇 > 0 negative)
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 0 個 hard + 1 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status