Dickinson H O, Nicolson D J, Campbell F, Cook J V, Beyer F R, Ford G A, Mason J
University of Newcastle, National Guideline Research & Development Unit, 21 Claremont Place, Newcastle upon Tyne, Tyne & Wear, UK NE2 4AA.
Cochrane Database Syst Rev. 2006 Jul 19(3):CD004640. doi: 10.1002/14651858.CD004640.pub2.
Epidemiological evidence on the effects of magnesium on blood pressure is inconsistent. Metabolic and experimental studies suggest that magnesium may have a role in the regulation of blood pressure.
To evaluate the effects of magnesium supplementation as treatment for primary hypertension in adults.
We searched the Cochrane Library, MEDLINE, EMBASE, Science Citation Index, ISI Proceedings, ClinicalTrials.gov, Current Controlled Trials, CAB abstracts, and reference lists of systematic reviews, meta-analyses and randomised controlled trials (RCTs) included in the review.
Inclusion criteria were: 1) RCTs of a parallel or crossover design comparing oral magnesium supplementation with placebo, no treatment, or usual care; 2) treatment and follow-up >/=8 weeks; 3) participants over 18 years old, with raised systolic blood pressure (SBP) >/=140 mmHg or diastolic blood pressure (DBP) >/=85 mmHg; 4) SBP and DBP reported at end of follow-up. We excluded trials where: participants were pregnant; received antihypertensive medication which changed during the study; or magnesium supplementation was combined with other interventions.
Two reviewers independently abstracted data and assessed trial quality. Disagreements were resolved by discussion or a third reviewer. Random effects meta-analyses and sensitivity analyses were conducted.
Twelve RCTs (n=545) with eight to 26 weeks follow-up met our inclusion criteria. The results of the individual trials were heterogeneous. Combining all trials, participants receiving magnesium supplements as compared to control did not significantly reduce SBP (mean difference: -1.3 mmHg, 95% CI: -4.0 to 1.5, I(2)=67%), but did statistically significantly reduce DBP (mean difference: -2.2 mmHg, 95% CI: -3.4 to -0.9, I(2)=47%). Sensitivity analyses excluding poor quality trials yielded similar results. Sub-group analyses and meta-regression indicated that heterogeneity between trials could not be explained by dose of magnesium, baseline blood pressure or the proportion of males among the participants.
AUTHORS' CONCLUSIONS: In view of the poor quality of included trials and the heterogeneity between trials, the evidence in favour of a causal association between magnesium supplementation and blood pressure reduction is weak and is probably due to bias. This is because poor quality studies generally tend to over-estimate the effects of treatment. Larger, longer duration and better quality double-blind placebo controlled trials are needed to assess the effect of magnesium supplementation on blood pressure and cardiovascular outcomes.
关于镁对血压影响的流行病学证据并不一致。代谢和实验研究表明，镁可能在血压调节中发挥作用。
评估补充镁作为治疗成人原发性高血压的效果。
我们检索了Cochrane图书馆、MEDLINE、EMBASE、科学引文索引、ISI会议录、ClinicalTrials.gov、当前对照试验、CAB文摘以及纳入本综述的系统评价、荟萃分析和随机对照试验（RCT）的参考文献列表。
入选标准为：1）平行或交叉设计的RCT，比较口服补充镁与安慰剂、不治疗或常规护理；2）治疗和随访≥8周；3）年龄超过18岁，收缩压（SBP）升高≥140 mmHg或舒张压（DBP）升高≥85 mmHg；4）随访结束时报告SBP和DBP。我们排除了以下试验：参与者为孕妇；接受了在研究期间发生变化的抗高血压药物治疗；或补充镁与其他干预措施联合使用。
两名评价员独立提取数据并评估试验质量。分歧通过讨论或第三名评价员解决。进行了随机效应荟萃分析和敏感性分析。
12项随访8至26周的RCT（n = 545）符合我们的入选标准。各试验结果存在异质性。综合所有试验，与对照组相比，接受镁补充剂的参与者并未显著降低SBP（平均差值：-1.3 mmHg，95%CI：-4.0至1.5，I² = 67%），但在统计学上显著降低了DBP（平均差值：-2.2 mmHg，95%CI：-3.4至-0.9，I² = 47%）。排除质量差的试验后的敏感性分析得出了类似结果。亚组分析和荟萃回归表明，试验之间的异质性无法用镁的剂量、基线血压或参与者中的男性比例来解释。
鉴于纳入试验的质量较差以及试验之间的异质性，支持补充镁与降低血压之间存在因果关联的证据薄弱，可能是由于偏倚。这是因为质量差的研究通常倾向于高估治疗效果。需要进行更大规模、更长持续时间和更高质量的双盲安慰剂对照试验，以评估补充镁对血压和心血管结局的影响。
