12-week nitrate-rich beetroot extract supplementation improves lower limb vascular function and serum angiogenic potential in postmenopausal women.

Postmenopausal women have reduced nitric oxide (NO) bioavailability and impairments within the microcirculation and lower limb conduit arteries, key factors contributing to cardiovascular disease (CVD) development and mortality. Dietary nitrate supplementation has shown promise in improving vascular function, yet most studies are limited to short-term interventions and upper-limb conduit artery function assessment. We investigated whether a 12-week nitrate-rich beetroot extract supplementation improves lower-limb conduit artery and skeletal muscle microvascular function, alongside serum angiogenic potential, in postmenopausal women. Postmenopausal women (60-85 years) were randomized to consume nitrate-rich (8.8 mmol nitrate, n=8) or nitrate-depleted beetroot extract (0.7 mmol nitrate, n=8) daily for 12 weeks. Femoral artery endothelial function was assessed via flow-mediated dilation (FMD), while tibialis anterior muscle microvascular reactivity was evaluated by near-infrared spectroscopy-derived reperfusion slope (StO2 Slope 2) every 4 weeks. Serum angiogenic potential was evaluated through endothelial tube formation assays using human umbilical vein endothelial cells. Serum nitrate increased significantly at weeks 4, 8, and 12 in the nitrate-rich group (p<0.05), with no changes in controls. Femoral artery FMD improved significantly after 12 weeks (p<0.05), while tibialis anterior microvascular reactivity increased after 8 and 12 weeks (p<0.05). Serum from nitrate-supplemented participants at week 12 induced a 1.8-fold increase in vitro tube formation compared to baseline (p<0.05). Collectively, the current findings suggest nitrate-rich beetroot extract as a potential dietary strategy to attenuate the vascular detrimental effects of menopause and reduce CVD risk in older women.