Citrulline / L-Citrulline for Hypertension
L-citrulline appears to lower blood pressure modestly, on the order of about 4 mmHg systolic, but the effect is small, the trials are short and tiny, and it is no substitute for proven first-line treatment. It earns a Weak Evidence (C) grade.
Why this grade7-layer evidence engine
Three meta-analyses point the same direction, which is why this isn't dismissed outright. A 2025 pooled analysis of 415 adults (PMID 40789388) found systolic pressure fell about 4.0 mmHg and diastolic about 2.5 mmHg, with a much larger drop (~10 mmHg systolic) when citrulline was combined with arginine. Two 2019 meta-analyses agree: PMID 31889969 reported brachial systolic -4.5 mmHg, and PMID 30788274 found systolic -4.1 mmHg, though diastolic only reached significance at doses of 6 g/day or more.
The grade stays at C rather than higher because the foundation is shaky. The supporting randomized trials are very small and low quality: a postmenopausal-women study (PMID 36297080, n=25) was underpowered to roughly nine per group, and an acute post-exercise study (PMID 39385595, n=20) tested only a single dose. The pooled trials mixed citrulline, watermelon extract, and citrulline malate, most ran only 4-8 weeks, funding was undisclosed, and one earlier meta-analysis was retracted and excluded.
Authorities are unconvinced. The EU's EFSA has issued no approved health claims and unfavorable opinions; the US FDA treats citrulline only as a dietary-supplement ingredient with no endorsement; NHS and WHO do not address it. The Mayo Clinic (via arginine) says it 'might' help but warns it can stack dangerously with blood-pressure drugs. The ~4 mmHg effect is far below diet, exercise, or medication, so it cannot be claimed to treat hypertension.
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 = 0.613
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高品質 SR/MA 顯示 positive (2 篇 > 0 negative)
- tier_strict_requirement_check — | B→C 因 scope.conflation_risk=true 且 L11 獨評較低 (B7-2 tier cap)
- detect_disputes — 偵測到 0 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status