Effects of dietary nitrate and vitamin C co-ingestion on blood pressure and hand-grip strength in young adults.

ABSTRACT

Background: Co-administration of vitamin C and inorganic nitrate ([Formula see text]) may reduce oxidative stress, boost the conversion of nitrite ([Formula see text]) into NO and elicit positive vascular effects. Aims: We aimed to test the effects of oral inorganic [Formula see text] and vitamin C co-supplementation on vascular function, muscular strength, and on concentrations of urinary [Formula see text], vitamin C, 8-isoprostanes and salivary [Formula see text] in healthy young adults. Methods: Ten young healthy participants were enrolled in a randomised, double-blind (only for the [Formula see text] intervention) crossover clinical trial. Participants consumed in random order 1) nitrate-rich beetroot juice and vitamin C (N+VC), 2) nitrate-rich beetroot juice alone (N) or 3) nitrate-depleted beetroot juice alone (ND). Resting blood pressure (BP) was measured at the research centre and at home. Non-invasive, continuous measurements of BP and cardiac function parameters were performed using a Finometer device. Free-living physical activity and hand-grip strength were assessed. Salivary [Formula see text] and [Formula see text] and urinary [Formula see text], 8-isoprostanes and vitamin C concentrations were measured. Results: There were no significant differences for any of the vascular outcomes between the three interventions groups. However, analyses of within-intervention changes showed a significant lower daily systolic BP in the [Formula see text]+vitamin C (N+VC) group only (P=0.04). Urinary [Formula see text] (P=0.002) and salivary [Formula see text] (P=0.001) were significantly higher in the N+VC group compared to the N and ND groups. Conclusion: These preliminary findings suggest that combining dietary [Formula see text] with vitamin C could have protective effects on vascular function in young adults and could represent an effective strategy for the maintenance of healthy cardiovascular trajectories.