a Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University , Newcastle on Tyne , UK.
b Faculty of Applied Medical Sciences, Clinical Nutrition Department, Umm Al-Qura University , Makkah , Saudi Arabia.
Crit Rev Food Sci Nutr. 2019;59(15):2400-2410. doi: 10.1080/10408398.2018.1453779. Epub 2018 Jul 10.
We conducted a systematic review and meta-analysis of randomized clinical trials examining the effect of inorganic nitrate or nitrite supplementation on cognitive function (CF) and cerebral blood flow (CBF). Two databases (PubMed, Embase) were searched for articles from inception until May 2017. Inclusion criteria were: randomized clinical trials; participants >18 years old; trials comparing a nitrate/nitrite intervention with a control. Thirteen and nine trials were included in the meta-analysis to assess CF and CBF, respectively. Random-effects models were used and the effect size described as standardized mean differences (SMDs). A total of 297 participants (median of 23 per trial) were included for CF; 163 participants (median of 16 per trial) were included for CBF. Nitrate/nitrite supplementation did not influence CF (SMD +0.06, 95% CI: -0.06, 0.18, P = 0.32) or CBF under resting (SMD +0.14, 95% CI: -0.13, 0.41, P = 0.31), or stimulated conditions (SMD + 0.23, 95% CI: -0.11, 0.56, P = 0.19). The meta-regression showed an inverse association between duration of the intervention and CBF (P = 0.02) but no influence of age, BMI or dose ( < 0.05). Nitrate and nitrite supplementation did not modify CBF or CF. Further trials employing larger samples sizes and interventions with longer duration are warranted.
我们对考察无机硝酸盐或亚硝酸盐补充对认知功能（CF）和脑血流（CBF）影响的随机临床试验进行了系统评价和荟萃分析。从开始到 2017 年 5 月，我们在两个数据库（PubMed、Embase）中搜索了相关文章。纳入标准为：随机临床试验；参与者年龄＞18 岁；比较硝酸盐/亚硝酸盐干预与对照的试验。有 13 项和 9 项试验分别纳入荟萃分析以评估 CF 和 CBF。使用随机效应模型，以标准化均数差（SMD）描述效应大小。共有 297 名参与者（每项试验中位数为 23 名）纳入 CF 分析；163 名参与者（每项试验中位数为 16 名）纳入 CBF 分析。硝酸盐/亚硝酸盐补充并未影响 CF（SMD +0.06，95%CI：-0.06，0.18，P = 0.32）或静息状态下的 CBF（SMD +0.14，95%CI：-0.13，0.41，P = 0.31），或刺激状态下的 CBF（SMD +0.23，95%CI：-0.11，0.56，P = 0.19）。荟萃回归显示干预持续时间与 CBF 呈负相关（P = 0.02），但年龄、BMI 或剂量（＜0.05）无影响。硝酸盐和亚硝酸盐补充并未改变 CBF 或 CF。需要进一步开展样本量更大且干预持续时间更长的试验。
