Effect of DASH vs. Mediterranean diet on metabolic syndrome and cardiometabolic profile in adults with high normal blood pressure or grade 1 hypertension: the DASH-MedDiet randomized controlled trial

Background Lifestyle interventions are recommended as the first-line treatment to control metabolic syndrome components and improve cardiometabolic profile. However, studies directly comparing the effects of the Dietary Approaches to Stop Hypertension (DASH) vs. the Mediterranean diet (MedDiet) on metabolic syndrome prevalence and cardiometabolic risk factors are currently lacking. Purpose We aimed to assess the effects of a 3-month intensive dietary intervention implementing salt restriction either alone or on top of the DASH and MedDiet compared to no/ minimal intervention on metabolic syndrome prevalence and cardiometabolic profile in never drug-treated adults with high normal blood pressure (BP) or grade 1 hypertension. Methods We randomly assigned individuals to the control group (CG, n = 60), salt restriction group (SRG, n = 60), DASH diet with salt restriction group (DDG, n = 60), or MedDiet with salt restriction group (MDG, n = 60). All patients were followed monthly for 3 months in individual sessions coordinated by the clinical dietician. For the patients of all four study groups, the goal was to maintain the initial body weight unchanged. Patients in the CG received general advice on dietary principles for BP control. For the patients in all three intervention groups, the goal was to limit sodium intake to 2,000 mg/ day (equivalent to 5,0g salt/ day). In addition, patients in the DDG and the MDG received an individualized dietary plan with six daily sample menus to facilitate the adoption of the assigned dietary pattern. Anthropometric indices, dietary intake, office BP, and fasting blood samples were evaluated pre- and post-intervention. Results According to the intention-to-treat analysis, at 3 months post-intervention, the DDG and the MDG had lower odds ratio (OR) (95% CI) of metabolic syndrome [0.29 (0.12, 0.72), and 0.15 (0.06, 0.41), respectively] compared to the CG. Moreover, the MDG had lower odds of elevated BP levels compared to both the DDG and the SRG [0.08 (0.03, 0.19), and 0.13 (0.05, 0.34), respectively], and lower odds of metabolic syndrome compared to the SRG [0.25 (0.09, 0.67)]. In addition, the DDG and the MDG had lower odds of elevated fasting glucose compared to both the CG and the SRG, whereas the study groups did not differ regarding the odds of elevated waist circumference, elevated triglycerides, and reduced HDL- cholesterol. Regarding cardiometabolic indices, total and LDL-cholesterol, fasting glucose, HbA1c, and systolic/ diastolic BP were reduced in all three intervention groups compared to the CG. Conclusions On a background of salt restriction, the MedDiet was superior in BP reduction, but the DASH and MedDiet reduced the prevalence of metabolic syndrome to the same extent.