Influence of Dietary Approaches to Stop Hypertension (DASH) diet on blood pressure: a systematic review and meta-analysis on randomized controlled trials

Background and aims: Findings were not consistent on the therapeutic effect of Dietary Approaches to Stop Hypertension (DASH) diet on blood pressure. We aimed to review systematically and perform a meta-analysis to assess the magnitude of the effect of the DASH diet on blood pressure in randomized controlled trials (RCTs) among adults.

Methods and results: We conducted a systematic review and random effects meta-analysis of all RCTs which evaluated the effect of the DASH diet on blood pressure including published papers until June 2013, using PubMed, ISI Web of Science, Scopus and Google scholar database. Subgroup analysis and meta-regression were used to find out possible sources of between-study heterogeneity. Seventeen RCTs contributing 20 comparisons with 2561 participants were included. Meta-analysis showed that the DASH diet significantly reduced systolic blood pressure by 6.74 mmHg (95%CI: -8.25, -5.23, I(2) = 78.1%) and diastolic blood pressure by 3.54 mmHg (95%CI: -4.29, -2.79, I(2) = 56.7%). RCTs with the energy restriction and those with hypertensive subjects showed a significantly greater decrease in blood pressure. Meta-regression showed that mean baseline of SBP and DBP was explained 24% and 49% of the variance between studies for SBP and DBP, respectively.

Conclusion: The results revealed the profitable reducing effect of the DASH-like diet on both systolic and diastolic blood pressure in adults; although there was a variation in the extent of the fall in blood pressure in different subgroups.