Research

Hormonal

Oral L-citrulline supplementation (3–10 g/day) effectively increases plasma L-arginine and nitric oxide (NO) bioavailability, leading to reduced resting blood pressure and arterial stiffness in pre-hypertensive and hypertensive populations, whereas it fails to improve endothelial function (FMD) in healthy young individuals.

If you have high blood pressure, taking 3-10 grams of L-citrulline daily (or eating equivalent amounts of watermelon) can help lower your blood pressure and improve artery stiffness. This works best if you are already pre-hypertensive or hypertensive. If you are young and healthy, you likely won't see changes in your blood vessel dilation, so don't expect performance benefits from this specific mechanism.

GoodQualifiesHIGH confidence
Alternatively, oral L-citrulline supplementation consistently increases plasma and tissue levels of L-arginine and NO bioavailability [10–12]. ... L-citrulline supplementation has shown promise as a blood pressure lowering intervention (both resting and stress-induced) in adults with pre-/hypertension ... improvement in endothelial function, as measured by brachial artery flow mediated dilation (FMD), have not been reported with acute or short-term (~7 days) administration of L-citrulline ... in healthy, young participants
Timothy D. Allerton et al. · Nutrients · 2018

Why this rating

The paper is a review citing multiple human clinical trials showing BP reduction, but notes conflicting/negative results for FMD in healthy subjects.

Source

l-Citrulline Supplementation: Impact on Cardiometabolic Health

Timothy D. Allerton et al. · Nutrients · 2018

DOI 10.3390/nu10070921

narrative_reviewCited 227×
Read the paper
DOI resolved against Crossref · corpus check 2026-06-10

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