The DASH Diet Produces a Natriuretic Effect and Interacts with the Renin‐Angiotensin‐Aldosterone System

Abstract

The DASH diet is widely recommended to lower blood pressure, but its mechanisms of action are unclear. Lines of evidence suggest an interaction with the Renin‐Angiotensin‐Aldosterone system (RAAS), including ACE‐inhibitor or natriuretic effects. The DASH‐Diet in Isolated Systolic Hypertension (DASH‐DISH) trial is a randomized, controlled, cross‐over, study to test RAAS‐related mechanisms underlying the DASH diet effect. Following a one‐week run‐in diet on a Control diet (CON), subjects consumed a DASH and a CON diet for 4 weeks each in a randomized sequence. Calorie content was controlled to maintain weight and sodium was set at about 3 g daily. After each diet, subjects were admitted to a clinical research center where hormonal and hemodynamic assessments were obtained supine at baseline and in response to a RAAS inhibitor—captopril 25mg (CAP). This created four study groups; 1) DASH, 2) DASH+CAP, 3) CON, and 4) CON+CAP. Each group was also studied for responsiveness to a RAAS stimulator—a graded angiotensin II infusion (1ng and 3ng/kg × 45mins each). Primary outcomes were renal blood flow (RBF), mean arterial pressure (MAP), plasma renin activity (PRA), and aldosterone (ALDO). A repeated measure ANOVA was computed for primary outcomes with a Bonferroni adjustment and a statistical significance set at .0125. A total of 44 (19 female) hypertensive subjects (age 55.7±13.6 yrs, BMI 29.7±5.2 kg/cm2, BP 149/82±8/6 mmHg) completed the study protocol. DASH diet showed a trend towards lowered MAP vs CON (96.1±11.7 mmHg vs 98.8±14.1 mmHg, p = 0.07) and DASH+CAP significantly enhanced effects on MAP vs CON+CAP (83.2±10.7 mmHg vs 87.8±14.3 mmHg, respectively, p < 0.01). There were no differences in baseline RBF between the DASH and CON (p = 0.17). However, DASH+CAP increased RBF more than CON+CAP (486.46±149.38 cc/min vs 451.21±171.11 cc/min, p < 0.001). There were no baseline differences in PRA between the DASH and CON (p = 0.92) but DASH+CAP significantly increased PRA vs CON+CAP (1.52±1.78 cc/ml/min vs. 0.89±1.17 cc/ml/min; p < 0.001). DASH showed greater ALDO sensitivity to AngII infusion when compared to CON (17.40±7.74 ng/ml vs 13.84±6.21 ng/ml, p < 0.05) as did DASH+CAP vs CON+CAP (15.06±5.32 ng/ml vs 13.08±5.89 ng/ml, p < 0.05). These results suggest that the DASH diet produces a natriuretic effect in lowering blood pressure and stimulates the RAAS. The DASH diet might be particularly helpful in lowering BP in populations who benefit from a diuretic/natriuretic response and/or are concurrently prescribed RAAS antagonists.Support or Funding InformationNIH NHLBI: R01 HL77234, NIH NHLBI: K23 HL084236This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.