Effects of L-Citrulline Supplementation on Endothelial Function and Blood Pressure in Hypertensive Postmenopausal Women

Aging and menopause are associated with decreased nitric oxide bioavailability due to reduced L-arginine (L-ARG) levels contributing to endothelial dysfunction (ED). ED precedes arterial stiffness and hypertension development, a major risk factor for cardiovascular disease. This study investigated the effects of L-citrulline (L-CIT) on endothelial function, aortic stiffness, and resting brachial and aortic blood pressures (BP) in hypertensive postmenopausal women. Twenty-five postmenopausal women were randomized to 4 weeks of L-CIT (10 g) or placebo (PL). Serum L-ARG, brachial artery flow-mediated dilation (FMD), aortic stiffness (carotid-femoral pulse wave velocity, cfPWV), and resting brachial and aortic BP were assessed at 0 and 4 weeks. L-CIT supplementation increased L-ARG levels (Delta 13 +/- 2 vs. Delta-2 +/- 2 mu mol/L, p < 0.01) and FMD (Delta 1.4 +/- 2.0% vs. Delta-0.5 +/- 1.7%, p = 0.03) compared to PL. Resting aortic diastolic BP (Delta-2 +/- 4 vs. Delta 2 +/- 5 mmHg, p = 0.01) and mean arterial pressure (Delta-2 +/- 4 vs. Delta 2 +/- 6 mmHg, p = 0.04) were significantly decreased after 4 weeks of L-CIT compared to PL. Although not statistically significant (p = 0.07), cfPWV decreased after L-CIT supplementation by similar to 0.66 m/s. These findings suggest that L-CIT supplementation improves endothelial function and aortic BP via increased L-ARG availability.