BACKGROUND Emerging evidence suggests that increasing dietary nitrate intake may be an effective approach to reduce blood pressure. Beetroot juice is often used to supplement dietary nitrate, whereas nitrate intake levels from habitual diet are low. An increase in the habitual intake of nitrate-rich vegetables may represent an alternative to nitrate supplementation. However, the effectiveness and acceptability of a nitrate-rich-vegetables diet remain to be established. OBJECTIVE The aim was to investigate the effect and feasibility of two different intervention strategies to increase dietary nitrate intake, on plasma nitrate/nitrite concentrations and blood pressure. DESIGN A randomized, crossover trial was used. PARTICIPANTS Participants were healthy men and women (both n=15; age: 24±6 years) from the Netherlands. INTERVENTION Participants were instructed to consume ∼400 mg nitrate at lunch, provided through nitrate-rich vegetables and dietary counseling, or beetroot juice supplementation. Both interventions lasted 1 week, with 1-week washout (January to April 2017). MAIN OUTCOME Plasma nitrate and nitrite concentrations and resting systolic and diastolic blood pressure were measured in an overnight fasted state (before and after intervention) and ∼2.5 hours after lunch (before and throughout intervention on day 1, 4, and 7). STATISTICAL ANALYSIS Two-factor (time × treatment) repeated-measures analyses of variance were performed. RESULTS Mean plasma nitrate concentrations increased with both interventions, with a larger increase in beetroot juice vs nitrate-rich vegetables, both in a fasted state and ∼2.5 hours after lunch (day 1, beetroot juice: 2.31±0.56 mg/dL [373±90 μmol/L] vs nitrate-rich vegetables: 1.71±0.83 mg/dL [277±134 μmol/L]; P<0.001). Likewise, mean plasma nitrite concentrations increased with both interventions, but were higher after lunch in beetroot juice than in nitrate-rich vegetables (day 1: 2.58±1.52 μg/dL [560±331 nmol/L] vs 2.15±1.21 μg/dL [468±263 nmol/L]; P=0.020). Fasting mean systolic and diastolic blood pressure did not change, but mean systolic and diastolic blood pressure assessed ∼2.5 hours after lunch were significantly reduced throughout both intervention periods (P<0.05), with no differences between beetroot juice and nitrate-rich vegetables (day 1, systolic blood pressure: -5.1±9.5 mm Hg and diastolic blood pressure: -5.3±8.9 mm Hg). CONCLUSION Short-term consumption of dietary nitrate in the form of nitrate-rich vegetables represents an effective means to increase plasma nitrate and nitrite concentrations, and reduces blood pressure to the same extent as beetroot juice supplementation.

中文翻译：

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富含硝酸盐的蔬菜干预可提高健康年轻人的血浆硝酸盐和亚硝酸盐浓度并降低血压

背景 新出现的证据表明，增加膳食硝酸盐摄入量可能是降低血压的有效方法。甜菜根汁通常用于补充膳食硝酸盐，而习惯性饮食中的硝酸盐摄入量较低。增加富含硝酸盐的蔬菜的习惯摄入量可能是补充硝酸盐的替代方法。然而，富含硝酸盐的蔬菜饮食的有效性和可接受性仍有待确定。目的 目的是研究两种不同的干预策略对增加膳食硝酸盐摄入量、血浆硝酸盐/亚硝酸盐浓度和血压的效果和可行性。设计 使用随机、交叉试验。参与者参与者是来自荷兰的健康男性和女性（均为 n=15；年龄：24±6 岁）。干预 参与者被指示在午餐时摄入约 400 毫克硝酸盐，通过富含硝酸盐的蔬菜和饮食咨询或甜菜根汁补充剂提供。两种干预都持续了 1 周，有 1 周的洗脱期（2017 年 1 月至 4 月）。主要结果 血浆硝酸盐和亚硝酸盐浓度以及静息收缩压和舒张压在空腹状态下（干预前和干预后）和午餐后约 2.5 小时（第 1、4 和 7 天干预前和整个干预期间）测量。统计分析 进行了双因素（时间×治疗）重复测量方差分析。结果 两种干预措施均增加了平均血浆硝酸盐浓度，甜菜根汁与富含硝酸盐的蔬菜相比，在禁食状态和午餐后约 2.5 小时（第 1 天，甜菜根汁：2.31±0. 56 mg/dL [373±90 μmol/L] vs 富含硝酸盐的蔬菜：1.71±0.83 mg/dL [277±134 μmol/L]；P<0.001）。同样，两种干预措施均增加了平均血浆亚硝酸盐浓度，但午餐后甜菜根汁中的亚硝酸盐浓度高于富含硝酸盐的蔬菜（第 1 天：2.58±1.52 μg/dL [560±331 nmol/L] vs 2.15±1.21 μg/dL [468±263 nmol/L]；P=0.020)。空腹平均收缩压和舒张压没有变化，但在午餐后约 2.5 小时评估的平均收缩压和舒张压在两个干预期间均显着降低（P<0.05），甜菜根汁和富含硝酸盐的蔬菜（每天1、收缩压：-5.1±9.5 毫米汞柱和舒张压：-5.3±8.9 毫米汞柱）。