Effects of acute dietary nitrate supplementation on aortic blood pressures and pulse wave characteristics in post-menopausal women

Purpose: Consumption of nitrate-rich beetroot juice can lower blood pressure in peripheral as well as central arteries and may exert additional hemodynamic benefits (e.g. reduced aortic wave reflections). The specific influence of nitrate supplementation on arterial pressures and aortic wave properties in postmenopausal women, a group that experiences accelerated increases in these variables with age, is unknown. Accordingly, the primary aim of this study was to determine the effect of consuming nitrate-rich beetroot juice on resting brachial and aortic blood pressures (BP) and pulse wave characteristics in a group of healthy postmenopausal women, in comparison to a true (nitrate-free beetroot juice) placebo. Methods: Brachial (oscillometric cuff) and radial (SphygmoCor) pressures and derived-aortic waveforms were measured during supine rest in thirteen healthy postmenopausal women (63 ± 1 yr) before and 100 min after consumption of 140 ml of either nitrate-rich (9.7 mmol, 0.6 gm NO ₃ ⁻ ) or nitrate-depleted beetroot juice on randomized visits approximately 10 days apart (cross-over design). Ten young premenopausal women (22 ± 1 yr) served as a reference (non-supplemented) cohort. Results: Brachial and derived-aortic variables showed the expected age-associated differences in these women (all p < 0.05). In post-menopausal women, nitrate supplementation reduced (p < 0.05 vs. placebo visit) brachial systolic BP (BR _nitrate −4.9 ± 2.1 mmHg vs BR _placebo +1.1 ± 1.8 mmHg), brachial mean BP (BR _nitrate −4.1 ± 1.7 mmHg vs BR _placebo +0.9 ± 1.3 mmHg), aortic systolic BP (BR _nitrate −6.3 ± 2.0 mmHg vs BR _placebo +0.5 ± 1.7 mmHg) and aortic mean BP (BR _nitrate −4.1 ± 1.7 mmHg vs BR _placebo +0.9 ± 1.3 mmHg), and increased pulse pressure amplification (BR _nitrate +4.6 ± 2.0% vs BR _placebo +0.7 ± 2.5%, p = 0.04), but did not alter aortic pulse wave velocity or any other derived-aortic variables (e.g., augmentation pressure or index). Conclusions: Dietary nitrate supplementation favorably modifies aortic systolic and mean blood pressure under resting conditions in healthy postmenopausal women. Acute supplementation of nitrate does not, however, appear to restore indices of aortic stiffness in this group. Future work should evaluate chronic, long-term effects of this non-pharmacological supplement.