Black Seed for Hypertension
Black seed (Nigella sativa) consistently produces a small reduction in blood pressure in trials, but the effect is modest and unproven as a stand-alone therapy. We rate it Preliminary Evidence: a plausible adjunct, not a substitute for proven hypertension treatment.
Why this grade7-layer evidence engine
Three meta-analyses point the same direction. A 2016 review of 11 RCTs (n=860; PMID 27512971) found systolic BP fell about 3.3 mmHg and diastolic about 2.8 mmHg; a 2023 update (PMID 37341696) reported roughly 3.1 and 2.7 mmHg; and a 2025 GRADE-assessed dose-response analysis of 82 trials (n=5,026; PMID 40714301) again found significant improvement. The signal is real but small.
Several caveats keep this at a preliminary grade rather than higher. The benefit rests on a surrogate measure (blood pressure), not hard cardiovascular outcomes; trials are mostly small and short with largely undisclosed funding; statistical heterogeneity is substantial (I-squared near 60%); and preparations are inconsistent (the 2016 analysis favored powder, the 2023 update favored oil). A dedicated trial in elderly hypertensives (PMID 29348380) found only a non-significant downward trend, so the effect does not clearly generalize.
No authority endorses it for blood pressure. The US FDA recognizes black seed only as a GRAS spice and flavoring (21 CFR 182.10), with no approved health claim; Cleveland Clinic is cautious, while Mayo Clinic, Harvard Health and major societies do not address it. Because black seed can add to or interact with antihypertensive drugs, anyone on BP medication should use it only under medical supervision.
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 = 0.573
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高品質 SR/MA 顯示 positive (3 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