Spirulina for Hypertension
Spirulina shows a small, consistent ability to lower blood pressure across four meta-analyses, but the effect is modest and no health agency or clinical society endorses it for hypertension. It may be a minor adjunct, never a replacement for proven treatment.
Why this grade7-layer evidence engine
This earns a preliminary-evidence (B) rating because the four meta-analyses available all point the same direction, yet the signal stays small. A 2025 GRADE-assessed review (PMID 39529406) rated the evidence moderate quality and found spirulina cut systolic pressure by about 4.4 mmHg and diastolic by 2.8 mmHg, with larger drops in people who were hypertensive, overweight, over 50, or supplemented beyond eight weeks. A 35-trial, 1,523-participant analysis (PMID 40953712) and an edible-algae review (PMID 40726022) reported similar reductions of roughly 4-5 mmHg systolic, and an earlier 2021 pooled analysis (PMID 34578932) saw a steeper 9.2 mmHg systolic fall in hypertensive subgroups specifically.
The grade does not reach the top tier for several reasons. The headline effect in mixed populations is only about 4 mmHg, the high-quality trial volume is thin, funding and conflict-of-interest disclosures are largely absent across the analyses, and the included trials vary widely in dose (1-8 g/day) and duration. The promising subgroup results are hypothesis-generating rather than confirmed.
Crucially, the regulatory and clinical picture is silent rather than supportive. The US FDA has only addressed spirulina as a food ingredient (its GRAS notices state the agency had no questions about safety), while the EU, WHO and FAO offer no efficacy or blood-pressure endorsement. Mayo Clinic and Harvard have no dedicated guidance, Cleveland Clinic calls it merely promising, and no hypertension society (AHA, ASH) acknowledges it. Established options like the DASH diet and exercise lower pressure substantially more, so spirulina belongs only as a possible minor adjunct, not a substitute for prescribed care.
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 = 0.625
- 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