Effects of watermelon supplementation on arterial stiffness and wave reflection amplitude in postmenopausal women

Objective: Postmenopausal women have increased arterial stiffness (brachial-ankle pulse wave velocity [baPWV]) and wave reflection. L-Citrulline supplementation reduces baPWV but not brachial blood pressure. Peripheral vasodilators decrease wave reflection amplitude or second systolic peak (SBP2) in radial artery and aorta, which are related to aortic systolic blood pressure (SBP). We examined the effects of L-citrulline-rich watermelon supplementation on baPWV, wave reflection characteristics, and aortic SBP in postmenopausal women. Methods: In a randomized cross-over study, 12 postmenopausal women (mean [SE] age, 57 [1] y; mean [SE] body mass index, 38.1 [2.1] kg/m²; mean [SE] SBP, 153 [4] mm Hg) were assigned to watermelon supplementation (L-citrulline/L-arginine 6 g/d) or placebo supplementation for 6 weeks. Before and after each intervention, baPWV, aortic SBP, aortic diastolic blood pressure, aortic SBP2, radial SBP2, and aortic and radial augmentation indices were measured using applanation tonometry. Results: baPWV (-1.2 [0.3] m/s, P < 0.001), aortic SBP (-10 [3] mm Hg, P < 0.01), and aortic diastolic blood pressure (-7 [1] mm Hg, P < 0.001) decreased after watermelon supplementation compared with placebo. Although radial and aortic augmentation indices were unaffected, radial and aortic SBP2 decreased (-10 [3] mm Hg, P < 0.01) after watermelon supplementation compared with placebo. The reduction in aortic SBP was correlated with reductions in radial SBP2 (r = 0.99, P < 0.001) and aortic SBP2 (r = 0.98, P < 0.001). The decreases in baPWV correlated with reductions in radial SBP2 (r = 0.57, P < 0.01) and aortic SBP2 (r = 0.64, P < 0.01). Conclusions: Watermelon supplementation reduces arterial stiffness and aortic SBP by reducing pressure wave reflection amplitude in obese postmenopausal women with hypertension.