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

Background: Co-administration of vitamin C and inorganic nitrate () may reduce oxidative stress, boost the conversion of nitrite () into NO and elicit positive vascular effects. Aims: We aimed to test the effects of oral inorganic and vitamin C co-supplementation on vascular function, muscular strength, and on concentrations of urinary , vitamin C, 8-isoprostanes and salivary in healthy young adults. Methods: Ten young healthy participants were enrolled in a randomised, double-blind (only for the 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 and and urinary , 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 +vitamin C (N+VC) group only (P=0.04). Urinary (P=0.002) and salivary (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 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.