Effect of dietary approaches to stop hypertension or mediterranean diet on blood pressure in adults: a systematic review and meta-analysis

Objective: To determine whether the Dietary Approaches to Stop Hypertension (DASH) diet and the Mediterranean diet (MedDiet) is accompanied by blood pressure (BP) reduction in adults with and without hypertension. Design and method: We systematically searched Medline and the Cochrane Collaboration Library databases for randomized controlled trials (RCTs) investigating the BP effects of the DASH diet and the MedDiet in individuals with and without hypertension. We identified 30 RCTs (n = 5,545 participants) that explored the BP effects of the DASH diet compared to the control diet and 35 RCTs (n = 13,943 participants) that explored the MedDiet BP effects compared to the usual diet or another dietary intervention (e.g., lowfat diet). For each diet, the random-effects model was used to calculate the mean attained systolic BP (SBP) and diastolic BP (DBP) differences during followup. Results: Compared to the control diet, the DASH diet reduced SBP and DBP (difference in means: -3.2 mm Hg; 95% CI: -4.2, -2.3 mm Hg; P < 0.001, and -2.5 mm Hg; 95% CI: -3.5, -1.5 mm Hg; P < 0.001, respectively). Hypertension status did not modify the diets effects on BP reduction. Compared to the usual diet the MedDiet reduced SBP and DBP (difference in means: -3.1 mm Hg; 95% CI: -4.8, -1.3; P = 0.001, and -1.6 mm Hg; 95% CI: -2.6, -0.6; P = 0.002, respectively), while compared to all other active intervention diets or only to the low-fat diet the MedDiet did not reduce SBP or DBP. We were unable to compare the BP effects of the MedDiet between hypertensive and non-hypertensive patients, but in a limited number of studies conducted in normotensive individuals, the MedDiet BP effects were not significant. Conclusions: The adoption of the DASH diet or the MedDiet was accompanied by significant BP reduction in adults with and without hypertension. Our findings give further support to the current guidelines, supporting the adoption of a healthy, balanced diet, such as the DASH diet or the MedDiet.