Effect of 12-wk dietary nitrate supplementation on carotid arterial stiffness in postmenopausal females

Menopause is associated with reduced nitric oxide (NO) bioavailability, a key contributor to increased arterial stiffness and, consequently, greater risk of cardiovascular disease-related mortality in postmenopausal females. Even though dietary nitrate has been shown to increase NO bioavailability in postmenopausal females acutely, previous studies showed no impact of dietary nitrate supplementation on arterial stiffness in postmenopausal females. Their findings were likely limited by the acute and/or short-term design. Thus, this study aimed to determine whether 12 wk of dietary nitrate supplementation via beetroot extract improves carotid artery stiffness in postmenopausal females. A randomized, double-blind, placebo-controlled, and parallel-design trial was conducted with 20 postmenopausal females (60–85 yr). Participants received nitrate-rich (NR-BEETx, 8.8 mmol/day) or nitrate-depleted (ND-BEETx) beetroot extract. Carotid stiffness parameters—pulse wave velocity (PWVb), b stiffness, pressure-strain elastic modulus, augmentation index (AIx), and arterial compliance—were measured at baseline and weeks 4, 8, and 12. Serum nitrate and nitrite concentrations and blood pressure were also assessed. Compared with ND-BEETx, NR-BEETx supplementation significantly reduced PWVb, b stiffness, elastic modulus, and AIx at weeks 4, 8, and 12, whereas arterial compliance increased by week 12. Serum nitrate and nitrite concentrations were elevated five- to sixfold and 1.5- to 2-fold, respectively, in the NR-BEETx group, with peak concentrations occurring at week 8 and showing a plateau or slight decrease at week 12. Blood pressure remained unchanged in both groups. Twelve weeks of nitrate-rich beetroot extract supplementation improved carotid artery stiffness and increased NO bioavailability without altering blood pressure. These findings suggest that beetroot extract supplementation can be recommended as an alternative nutritional strategy to mitigate carotid artery stiffening in postmenopausal females.