Effects of dietary nitrate on cardiovascular reactivity in normotensive postmenopausal women

Menopause is associated with reduced estrogen and nitric oxide (NO) bioavailability, which may contribute to exaggerated blood pressure (BP) responses (i.e., reactivity) during exercise in postmenopausal women, partly via increased metaboreflex activation. Beetroot juice (BRJ), a source of inorganic nitrate, increases NO bioavailability and has been shown to lower resting BP; however, its effects on BP reactivity in postmenopausal women are less understood. We investigated whether BRJ alters BP reactivity in 14 healthy estrogen-deficient normotensive postmenopausal women (57 ± 4 years, 8 ± 5 years since menopause). Participants consumed 2 × 70 mL/day (800 mg nitrate) of BRJ or nitrate-depleted BRJ (placebo) for 4 days, separated by a washout period (≥ 7 days). Continuous beat-to-beat mean arterial BP (MAP) and heart rate (HR) were measured at rest and during isometric handgrip exercise (IHG; 30% of maximal voluntary contraction), post-exercise ischemia (PEI) and cold pressor test (CPT). Data is presented as mean ± SD. We found no difference in the peak MAP response to IHG (Δ 16 ± 8 vs. 16 ± 6 mmHg, p = 0.60), PEI (Δ 11 ± 4 vs. 12 ± 7 mmHg, p = 0.32) or CPT (Δ 23 ± 11 vs 23 ± 10 mmHg, p = 0.93) between BRJ intake and placebo. Likewise, no difference was observed for SBP, DBP, or HR responses to either stressor (all: p>0.05). These findings suggest that short-term inorganic nitrate supplementation does not modify cardiovascular reactivity to IHG, PEI or CPT in healthy postmenopausal women.