Increasing Nitrate-Rich Vegetable Intake Lowers Ambulatory Blood Pressure in (pre)Hypertensive Middle-Aged and Older Adults: A 12-Wk Randomized Controlled Trial

Background: Emerging evidence suggests that increasing dietary nitrate intake may be an effective approach to Improve cardiovascular health. However, the effects of a prolonged elevation of nitrate intake through an increase in vegetable consumption are understudied.Objective: Our primary aim was to determine the impact of 12 wk of increased daily consumption of nitrate-rich vegetables or nitrate supplementation on blood pressure (BP) in (pre)hypertensive middle-aged and older adults.Methods: In a 12-wk randomized, controlled study (Nijmegen, The Netherlands), 77 (pre)hypertensive participants (BP: 144 +/- 13/87 +/- 7 mmHg, age: 65 +/- 10 y) either received an intervention with personalized monitoring and feedback aiming to consume similar to 250-300 g nitrate-rich vegetables/d (similar to 350-400 mg nitrate/d; n = 25), beetroot juice supplementation (400 mg nitrate/d; n = 26), or no intervention (control; n = 26). Before and after intervention, 24-h ambulatory BP was measured. Data were analyzed using repeated measures ANOVA (time x treatment), followed by within-group (paired t-test) and between-group analyses (1-factor ANOVA) where appropriate.Results: The 24-h systolic BP (SBP) (primary outcome) changed significantly (P-interaction time x treatment = 0.017) with an increase in the control group (131 +/- 8 compared with 135 +/- 10 mmHg; P = 0.036); a strong tendency for a decline in the nitrate-rich vegetable group (129 +/- 10 compared with 126 +/- 9 mmHg; P = 0.051) which was different from control (P = 0.020); but no change in the beetroot juice group (133 +/- 11 compared with 132 +/- 12 mmHg; P = 0.56). A significant time x treatment interaction was also found for daytime SBP (secondary outcome, P = 0.011), with a significant decline in the nitrate-rich vegetable group (134 +/- 10 compared with 129 +/- 9 mmHg; P = 0.006) which was different from control (P = 0.010); but no changes in the beetroot juice (138 +/- 12 compared with 137 +/- 14 mmHg; P = 0.41) and control group (136 +/- 10 compared with 137 +/- 11 mmHg; P = 0.08). Diastolic BP (secondary outcome) did not change in any of the groups.Conclusions: A prolonged dietary intervention focusing on high-nitrate vegetable intake is an effective strategy to lower SBP in (pre)hypertensive middle-aged and older adults.