Sodium reduction is the key ingredient in dietary treatment of hypertension - a randomized controlled trial on sodium, potassium and nitrate.

Dietary interventions are recommended as part of hypertension (HTN) treatment. Sodium reduction has proven effective, however supplements of potassium and/or nitrate are likely also of importance. We aimed to test how these three dietary components affect blood pressure (BP) individually and in combination in patients with HTN. A double-blind randomized controlled trial of 90 participants with HTN was conducted. Participants were randomized to eight groups receiving a hand-out diet and different combinations of supplementation of sodium chloride (130 mmol/day), potassium chloride (40 mmol/day) and beetroot juice (BRJ) with nitrate (13 mmol/day) or for each a matching placebo. The intervention lasted one week. 24 h BP, blood samples and 24 h urine collection were conducted before and after. We found a strong association between change in BP and sodium reduction (p < 0.0001). The change in systolic BP in the low-sodium groups was -7 mmHg (95% CI -9;-5) and no change was found in the high-sodium groups. We found a BP reduction in the low-potassium vs. the high-potassium groups (p = 0.03). Nitrate supplementation was not related to change in BP (p = 0.31). Plasma aldosterone and aldosterone-to-renin ratio (ARR) were associated to the change in BP in the low-sodium groups. In conclusion, in this one week intervention we found sodium reduction to be the important dietary alteration in matters of lowering BP. BRJ with nitrate and potassium chloride supplements did not assist in decreasing BP during this short-time intervention. Measuring ARR might be relevant in a clinical setting to predict the BP effect of sodium reduction. URL: https://www.clinicaltrialsregister.eu . Unique identifier: 2021-003407-17.