Big effect
A meta-analysis found L-citrulline plus L-arginine slashed systolic blood pressure by 10.4 mmHg — but the finding comes from only 415 people in a specific elderly population.
This is an unusually large drop for a supplement combo, but the evidence pool is thin: only three studies synthesized, mostly showing moderate effects, and the result may not apply to younger or healthier adults.
A systematic review of trials in middle-aged and older adults found that taking L-citrulline and L-arginine together lowered systolic blood pressure by about 10 mmHg, with the combination outperforming either supplement alone. The effect is striking, but the meta-analysis included just 415 participants total, and the overall strength of the evidence for L-arginine's blood-pressure benefit is rated low.
Where this fits in the evidence
Pillser has synthesized 5 studies on L-Arginine for Reduced Systolic Blood Pressure — overall evidence strength: Moderate.
Across 5 studies, 3 reported beneficial effects of L-arginine on systolic blood pressure, with effect sizes ranging from moderate to large (one moderate, one large, one moderate). The remaining 2 studies found neutral effects. Evidence is strongest for pregnant women and elderly populations, but results are mixed: a meta-analysis in pregnant women (2028 participants) showed a moderate reduction (MD -5.64 mmHg, very low certainty), while another systematic review in high-risk pregnancies found no statistically significant difference. One study in middle-aged/elderly individuals reported a large reduction (-10.44 mmHg) when combined with L-citrulline. Doses and durations were not consistently reported across studies.
The study
- Meta-Analysis
- n = 415
- 2025-10
- Clinical nutrition ESPEN
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