Magnesium for Hypertension
Magnesium supplements produce a small but real reduction in blood pressure, on the order of 1-3 mmHg overall. The benefit is concentrated in people who are magnesium-deficient or already on antihypertensive medication, and it is not a substitute for first-line treatment.
Why this grade7-layer evidence engine
This earns a Preliminary (B) grade because four high-quality meta-analyses agree on direction but report only a modest effect. The largest, a 2025 AHA review of 38 trials (PMID 41000008), found systolic BP fell 2.81 mmHg overall; a 2024 umbrella review of 10 meta-analyses (PMID 39280209) put it lower at 1.25 mmHg. Two earlier meta-analyses (PMID 27402922, PMID 28724644) reported similar 2-4 mmHg drops. The signal is consistent, but the size is small versus the 8-15 mmHg from standard blood-pressure drugs.
The grade stops short of A for two reasons. First, the effect is driven by specific subgroups: in medicated hypertensives systolic BP fell 7.68 mmHg and in magnesium-deficient people 5.97 mmHg (PMID 41000008), while normotensive adults saw no significant change. Second, heterogeneity between trials is high and the 2025 analysis found no clear dose-response, so the average benefit for an unselected person is genuinely modest.
Regulators and clinics mirror this caution. The US FDA allows only a qualified health claim and NIH ODS notes the evidence is inconsistent; the UK NHS, Cleveland Clinic and AHA steer people toward dietary magnesium and the DASH pattern rather than pills, and Harvard says supplements 'may modestly lower' BP. A transparency flag also applies: two of the four meta-analyses share a co-author from an advocacy-aligned magnesium research group that petitioned for the FDA claim. Bottom line: a reasonable adjunct for deficient or medicated patients, not a standalone therapy.
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 = 0.602
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高品質 SR/MA 顯示 positive (4 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