Vitamin B2 (Riboflavin) for Migraine
High-dose riboflavin (vitamin B2), typically 400 mg/day for at least three months, has preliminary evidence that it can modestly reduce how often adults get migraine attacks. It is not a painkiller for an attack in progress, and the benefit appears limited to attack frequency rather than how long or how severe each migraine is.
Why this grade7-layer evidence engine
This earns a B (preliminary evidence) grade because the supportive data are consistent but thin. The anchor is a small double-blind RCT (Schoenen 1998, PMID 9484373): 400 mg/day for three months left 59% of patients with at least a 50% drop in attack frequency versus 15% on placebo (p=0.005, NNT 2.3), and significantly fewer headache days (p=0.012), though attack severity did not change. An open-label study (Boehnke 2004, PMID 15257686) saw attacks fall from 4 to 2 per month, and two systematic reviews (Thompson 2017, PMID 28485121; Namazi 2015) found 9 of 11 studies positive in adults.
The grade does not climb higher because the evidence base is modest: the anchor trial was small, single-center and industry-funded, with no large independent RCT replicating it. A combination trial (Maizels 2004, PMID 15447697) is confounded by using low-dose riboflavin as its 'placebo,' so it cannot prove efficacy. Pediatric trials at 50-200 mg/day were inconclusive, so the benefit applies to adults at the full 400 mg dose.
Authorities are split, which keeps expectations measured. Cleveland Clinic and Harvard Health cautiously endorse it for prevention at 400 mg/day, but Mayo Clinic lists migraine as an unproven use. Regulators (EFSA, NHS) only recognize riboflavin's basic nutritional roles and have never approved a migraine treatment claim, with NHS noting limited evidence for high-dose use. Safety is excellent: the main effect is harmless bright-yellow urine.
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 = 0.631
- 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 + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status