英国伦敦大学玛丽皇后学院Feng J He团队取得一项新突破。他们分析了减少膳食钠的剂量和持续时间对血压水平的影响。相关论文发表在2020年2月25日出版的《英国医学杂志》上。

为了探讨减少膳食钠与血压变化之间的剂量反应关系，以及持续时间的影响，研究组对MEDLINE等大型数据库中截至2019年1月21日的文献进行筛选，检索出比较成人不同钠摄入量与24小时尿钠排泄量来估算摄入量的随机试验，并对这些试验进行荟萃分析。

最终共纳入133项研究，涉及12197名参与者。24小时尿钠中位减少130mmol，收缩压（SBP）平均降低4.26mmHg，舒张压（DBP）平均降低2.07mmHg。24小时钠排泄量每降低50mmol，SBP降低1.10mmHg，DBP降低0.33mmHg。

在参与者中，无论高血压还是非高血压，都能观察到血压下降。当24小时尿钠减少值一样时，老年人，非白人和基线SBP较高的人群的SBP降低幅度更大。

在持续时间少于15天的试验中，24小时尿钠排泄量每减少50mmol，SBP下降1.05mmHg；而在持续时间较长的研究中，24小时尿钠排泄量每减少50mmol，SBP下降2.13mmHg。除此之外，试验持续时间与SBP降低之间没有关联。

减少钠摄入量与血压降低的幅度呈剂量反应关系，年龄较大、非白人和血压较高的人群降低幅度更大。短期研究低估了减少钠摄入量对血压的影响。

附：英文原文

Title: Effect of dose and duration of reduction in dietary sodium on blood pressure levels: systematic review and meta-analysis of randomised trials

Author: Liping Huang, Kathy Trieu, Sohei Yoshimura, Bruce Neal, Mark Woodward, Norm R C Campbell, Qiang Li, Daniel T Lackland, Alexander A Leung, Cheryl A M Anderson, Graham A MacGregor, Feng J He

Issue&Volume: 2020/02/25

Abstract: AbstractObjective To examine the dose-response relation between reduction in dietary sodium and blood pressure change and to explore the impact of intervention duration.Design Systematic review and meta-analysis following PRISMA guidelines.Data sources Ovid MEDLINE(R), EMBASE, and Cochrane Central Register of Controlled Trials (Wiley) and reference lists of relevant articles up to 21 January 2019.Inclusion criteria Randomised trials comparing different levels of sodium intake undertaken among adult populations with estimates of intake made using 24 hour urinary sodium excretion.Data extraction and analysis Two of three reviewers screened the records independently for eligibility. One reviewer extracted all data and the other two reviewed the data for accuracy. Reviewers performed random effects meta-analyses, subgroup analyses, and meta-regression.Results 133 studies with 12197 participants were included. The mean reductions (reduced sodium v usual sodium) of 24 hour urinary sodium, systolic blood pressure (SBP), and diastolic blood pressure (DBP) were 130 mmol (95% confidence interval 115 to 145, P<0.001), 4.26 mm Hg (3.62 to 4.89, P<0.001), and 2.07 mm Hg (1.67 to 2.48, P<0.001), respectively. Each 50 mmol reduction in 24 hour sodium excretion was associated with a 1.10 mm Hg (0.66 to 1.54; P<0.001) reduction in SBP and a 0.33 mm Hg (0.04 to 0.63; P=0.03) reduction in DBP. Reductions in blood pressure were observed in diverse population subsets examined, including hypertensive and non-hypertensive individuals. For the same reduction in 24 hour urinary sodium there was greater SBP reduction in older people, non-white populations, and those with higher baseline SBP levels. In trials of less than 15 days’ duration, each 50 mmol reduction in 24 hour urinary sodium excretion was associated with a 1.05 mm Hg (0.40 to 1.70; P=0.002) SBP fall, less than half the effect observed in studies of longer duration (2.13 mm Hg; 0.85 to 3.40; P=0.002). Otherwise, there was no association between trial duration and SBP reduction.Conclusions The magnitude of blood pressure lowering achieved with sodium reduction showed a dose-response relation and was greater for older populations, non-white populations, and those with higher blood pressure. Short term studies underestimate the effect of sodium reduction on blood pressure.

DOI: 10.1136/bmj.m315

Source: https://www.bmj.com/content/368/bmj.m315