Grape Seed Extract for Hypertension
Grape seed extract may produce a small drop in blood pressure, but the evidence is weak and inconsistent, with the most rigorous analysis finding no significant effect on systolic pressure. It is not a substitute for proven first-line measures.
Why this grade7-layer evidence engine
The grade is C (weak evidence) because the meta-analyses genuinely disagree rather than simply showing a modest effect. An older 2016 meta-analysis of 16 trials (PMID 27537554, n=810) found significant reductions in both systolic (-6.1 mmHg) and diastolic (-2.8 mmHg) pressure, but a more rigorous 2022 dose-response meta-analysis (PMID 34798267) found only diastolic pressure significantly lowered (-2.2 mmHg) while systolic pressure was not significant, with extreme statistical heterogeneity (systolic I-squared 97.4%) that makes the pooled numbers unstable.
Supporting data are thin and skewed toward specific groups. A proanthocyanidin meta-analysis (PMID 33465473) reported significant systolic and diastolic reductions but rested on just 6 trials (376 people), and the main pre-hypertension trial (PMID 26568249) had only 36 participants, high dropout, and low quality. Across studies the effect is small (~2-6 mmHg) and concentrated in younger, obese, and metabolic-syndrome subgroups rather than the general hypertensive population.
Regulators and clinics do not endorse this use. The EU's EFSA rejected the grape seed extract blood-pressure health claim for failing to establish cause and effect, the US FDA has treated disease claims for these compounds as unauthorized drug claims, and no major clinical body (NIH ODS, Mayo Clinic, Cleveland Clinic, Harvard) addresses grape seed extract for hypertension. Funding is largely undisclosed, raising industry conflict-of-interest concerns, and proven steps like the DASH diet, exercise, and medication remain first-line.
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 = 0.449
- 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 + 1 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status