Effects of chronic salt loading and potassium supplementation on blood pressure variability in healthy adults

AIM:To explore the effects of chronic salt loading and potassium supplementation on blood pressure variability in healthy adults. METHODS: One hundred normotensive subjects aged 28 to 60 years were enrolled and sequentially maintained on a protocol of a 3-day baseline investigation, a 7-day low-salt diet (3 g/day, NaCl), a 7-day high-salt diet (18 g/day), and a high-salt diet with potassium supplementation (4.5 g/day, KCl) for another 7 days. On the last 3 days of each period, blood pressure was measured. Day-to-day variability in systolic blood pressure (SBP) and diastolic blood pressure (DBP) was expressed as the standard deviation and coefficient of variation. RESULTS: Blood pressure decreased after salt restriction ［SBP: (112±11) vs. (117±14) mmHg, P<0.01; DBP: (74±8) vs. (76±10)mmHg, P<0.01］ and increased after salt loading ［SBP: (119±14) vs.(112±11)mmHg, P<0.01; DBP: (77±9) vs. (74±8) mmHg, P<0.01］. At potassium supplementation stage, blood pressure decreased ［SBP: (114±12) vs. (119±14) mmHg, P<0.01; DBP: (75±8) vs. (77±9) mmHg, P<0.01］. Compared with those during the baseline period, day-to-day variability of blood pressure decreased during the salt-restriction period ［SBP: (3.9±1.5) vs. (4.3±1.0) mmHg, P<0.01; DBP: (3.2±1.4) vs. (3.6±1.6 mmHg), P<0.01］ and increased after salt loading ［SBP: (4.4±1.6) vs. (3.9±1.5) mmHg, P<0.05; DBP: (3.7±1.2) vs. (3.2±1.4) mmHg, P<0.05］. CONCLUSION: Dietary salt is associated with blood pressure. Blood pressure decreases after salt restriction but increases after salt loading. Potassium supplementation decreases blood pressure after salt loading. Low-salt diet lowers blood pressure variability and is an important factor for prevention of hypertension and target organ damage.