Vitamin B6 (Pyridoxine / Pyridoxal-5'-Phosphate) for Premenstrual Syndrome
Vitamin B6 (50–100 mg/day) appears to modestly ease overall premenstrual symptoms and premenstrual low mood, but the supporting trials are mostly small and methodologically dated, so this rates as preliminary rather than firmly established. It is best viewed as a low-risk adjunct, not a replacement for first-line PMS treatment.
Why this grade7-layer evidence engine
The grade reflects a consistent but limited evidence base. The landmark Wyatt meta-analysis of nine trials (PMID 10334745, n=940) found B6 more than twice as likely as placebo to relieve overall PMS symptoms (OR 2.32, 95% CI 1.95-2.54) and depressive symptoms (OR 1.69, 95% CI 1.39-2.06), favoring doses up to 100 mg/day. Smaller later randomized trials reproduced this signal: a triple-blind RCT at 40 mg/day (PMID 21241460, n=90, P<0.05) and a double-blind RCT at 80 mg/day (PMID 26989667, n=94, P<0.001). A magnesium-plus-B6 trial (PMID 33210604, n=264) also hinted at added mood benefit.
It stays at preliminary rather than strong evidence because the trials are small, use inconsistent PMS scales, and rely on older blinding methods; the authors themselves graded the body of evidence as only moderate quality. Professional bodies treat B6 as a 'may consider' option, not a first-line therapy. The Cleveland Clinic notes only that 'vitamins such as B-6 and magnesium may also reduce your symptoms,' without endorsing a specific dose.
Safety is the key caveat. The doses studied for PMS (40-100 mg/day) exceed several regulators' supplement limits: UK NHS advises no more than 10 mg/day from supplements without medical advice, EFSA sets a tolerable upper limit of 12.5 mg/day, and chronic intake at or above 200 mg/day can cause peripheral nerve damage. Australia will restrict doses above 50 mg/day to pharmacist supply from 2027. Effective doses therefore warrant caution and ideally clinician guidance.
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 = 0.691
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高品質 SR/MA 顯示 positive (1 篇 > 0 negative)
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 0 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status