J Acad Nutr Diet. 2020 Aug;120(8):1305-1317. doi: 10.1016/j.jand.2020.02.014. Epub 2020 May 5.
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.
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.
A randomized, crossover trial was used.
Participants were healthy men and women (both n=15; age: 24±6 years) from the Netherlands.
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).
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).
Two-factor (time × treatment) repeated-measures analyses of variance were performed.
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).
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.
新出现的证据表明，增加膳食硝酸盐的摄入可能是降低血压的有效方法。甜菜根汁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性摄入可能是替代硝酸盐补充的一种方法。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。
本研究旨在调查两种不同的增加膳食硝酸盐摄入的干预策略的效果和可行性，即通过富含硝酸盐的蔬菜和饮食咨询或甜菜根汁补充来提高血浆硝酸盐/亚硝酸盐浓度和血压。
采用随机交叉试验。
参与者为来自荷兰的健康男性和女性（均为 15 名；年龄：24±6 岁）。
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来提供。两种干预措施均持续 1 周，洗脱期为 1 周（2017 年 1 月至 4 月）。
在禁食过夜状态下（干预前后）和午餐后约 2.5 小时（干预第 1、4 和 7 天的整个过程中）测量血浆硝酸盐和亚硝酸盐浓度以及静息收缩压和舒张压。
采用双因素（时间×处理）重复测量方差分析。
两种干预措施均使平均血浆硝酸盐浓度升高，甜菜根汁比富含硝酸盐的蔬菜升高更明显，无论是在禁食状态还是午餐后约 2.5 小时（第 1 天，甜菜根汁：2.31±0.56mg/dL[373±90μmol/L] vs 富含硝酸盐的蔬菜：1.71±0.83mg/dL[277±134μmol/L]；P<0.001）。同样，平均血浆亚硝酸盐浓度也随着两种干预措施而升高，但甜菜根汁在午餐后的升高幅度高于富含硝酸盐的蔬菜（第 1 天：2.58±1.52μg/dL[560±331nmol/L] vs 2.15±1.21μg/dL[468±263nmol/L]；P=0.020）。空腹平均收缩压和舒张压没有变化，但午餐后约 2.5 小时测量的平均收缩压和舒张压均显著降低（P<0.05），甜菜根汁和富含硝酸盐的蔬菜之间没有差异（第 1 天，收缩压：-5.1±9.5mmHg 和舒张压：-5.3±8.9mmHg）。
短期摄入富含硝酸盐的蔬菜形式的膳食硝酸盐是增加血浆硝酸盐和亚硝酸盐浓度的有效方法，并且与甜菜根汁补充一样能降低血压。
