The effects of dietary sodium on blood pressure in normotensive adults is not well characterized. The Study of Sodium and Blood Pressure (SNaP) is a randomized, double-blind crossover trial using a placebo or 96 meq sodium in 4-week treatment periods separated by a 2-week washout period. Before capsule treatment periods, participants were instructed in a low sodium diet for 10 weeks to reduce urinary sodium excretion to less than 35 meq/8 hr. The low sodium diet was continued throughout the capsule treatment periods. Participants (n=48; 47 white, 1 black) were 79% male and had an average age of 52 years, a body mass index of 27.6, and a baseline blood pressure of 131/84 mm Hg. Baseline overnight urinary sodium excretion was 51 meq/8 hr and 19 meq/8 hr after the low sodium diet run-in period, before the capsule treatment periods began. Resting, seated blood pressure was measured twice at each visit in a standard fashion. Differences between sodium and placebo treatment periods were as follows: systolic blood pressure, 123.9 versus 1203 mm Hg, respectively p<0.001); diastolic blood pressure, 78.7 versus 76.4 mm Hg, respectively (p=0.005); and sodium excretion, 513 versus 30.9 meq/8 hr, respectively (p<0.001). Both systolic and diastolic blood pressures increased significant amounts in normotensive adults on a low sodium diet supplemented with 96 meq/day sodium. Long-term effects and doseresponse relations need further study.
- Blood pressure
- Clinical trials