Effects of Sodium and Potassium Supplementation on Blood Pressure and Arterial Stiffness in Untreated (Pre)Hypertensives on a Low-Sodium, Low-Potassium Diet

Introduction: We performed a 12-week randomized placebo-controlled crossover study to examine the effects of sodium and potassium supplementation on blood pressure (BP) and arterial stiffness in untreated (pre)hypertensive individuals on a low-sodium, low-potassium diet. Methods: During the study, subjects were on a fully controlled diet that provided on average 2.4 g/d of sodium (equals 6 g/d of salt) and 2.2 g/d of potassium. After a 1-week run-in period, 37 subjects received capsules with supplemental sodium (3 g/d, equals 7.5 g/d of salt), supplemental potassium (3 g/d), or placebo, for four weeks each (not separated by wash-out), in random order. Fasting office BP, 24-h ambulatory BP, and measures of arterial stiffness (SphygmoCor®) were assessed at baseline and after each treatment. Results: Subjects had a mean pre-treatment BP of 145/81 mmHg and 68% (25 of 37) had systolic BP (SBP) =140 mmHg. In 36 subjects who completed the study, sodium supplementation increased urinary sodium by 97.6 mmol/24h (2.2 g/d) and potassium supplementation increased urinary potassium by 62.9 mmol/24h (2.5 g/d), compared to placebo (Table). Sodium supplementation significantly increased office BP by 7.5/3.3 mmHg, 24-h BP by 7.0/2.1 mmHg and central BP by 8.5/3.6 mmHg. Potassium supplementation significantly reduced 24-h BP by 4.0/1.7 mmHg. Measures of arterial stiffness did not change. Conclusion: Increasing the intake of sodium has a strong adverse effect on BP in untreated (pre)hypertensive individuals. Increased potassium intake, however, lowers BP even when people are on a reduced sodium diet. Short-term changes in sodium and potassium intake have little effect on arterial stiffness