Bilberry for Peripheral Circulation
Despite older traditional-use approvals, modern high-quality research has not shown that bilberry meaningfully improves peripheral circulation, and a 2025 expert vascular panel deliberately left it off its list of supported supplements. On current evidence, it should not be relied on to treat poor circulation.
Why this grade7-layer evidence engine
The grade is driven by what modern, higher-quality studies actually found. A 2021 systematic review and meta-analysis of anthocyanin-rich berries (PMID 34977111) reported no significant improvement in blood-vessel function (flow-mediated dilation: WMD 1.20%, p=0.096), and the bilberry-only subgroups for cholesterol and triglycerides were likewise non-significant. A 2022 systematic review of Vaccinium myrtillus (PMID 36678645) added no new circulation trials and covered leaves rather than the fruit extract typically sold for this use.
Most tellingly, a 2025 Delphi consensus of Italian vascular specialists (PMID 41470775) endorsed several venoactive agents but specifically excluded bilberry-class anthocyanosides, citing heterogeneous, low-certainty evidence and inconsistent extract standardization. The supportive signals are weaker than they appear: a WHO monograph lists peripheral vascular insufficiency among traditional uses, but it leans on small, single-blind 1980s Italian trials, and an animal study (PMID 1796918) shows only a plausible microcirculation mechanism, not a human benefit.
Regulators and clinics reinforce the caution. The US FDA quote comes from a warning letter against an unapproved circulation claim, not an endorsement, and EFSA has left bilberry circulation claims unapproved. Major clinical bodies (NIH ODS, Mayo Clinic, Cleveland Clinic, Harvard Health) say nothing about bilberry for circulation. People on blood thinners or antiplatelet drugs should be especially cautious, and proven first-line measures such as supervised exercise and risk-factor control remain the better choice.
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 = 0.568
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高品質 SR/MA 顯示 negative 主導 (2 negative > 0 positive)，下層 RCT 不能推翻
- apply_hec_override — HEC-1 高階證據 negative — 強制由 B 改為 D
- 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