Nitric Oxide (NO) produced from l-arginine by endothelial NO synthase (eNOS) plays an important role in regulating endothelium-dependent vasodilatation. L-citrulline is a colorless, water-soluble α-amino acid that is a potent endogenous precursor of l-arginine. In a recent clinical study, l-citrulline supplementation dose-dependently increases plasma l-arginine levels in healthy human volunteers more effectively than equivalent doses of l-arginine itself. Furthermore, researchers have demonstrated in clinical trials that l-citrulline supplementation functionally improves arterial stiffness, decreases the state of lipoprotein oxidation, reduces ankle blood pressure and carotid wave reflection, and causes a reduction in the heart rate-corrected QT interval as a marker of sudden cardiac death. Thus, l-citrulline supplementation has been shown to exhibit several beneficial effects on the cardiovascular system. Compared with the single amino acid use of l-arginine alone or l-citrulline alone, simultaneous administration with l-citrulline and l-arginine rapidly raised plasma l-arginine levels, with time to reach peak concentration of less than an hour after supplementation. Data suggests the clinical benefit on vascular function of l-citrulline plus l-arginine supplementation in combination vs being taken alone.
Nutrients. 2018 Jul; 10(7): 921.
