Dietary Sodium Restriction and SBP in Older Adults
The DASH trial recently demonstrated the efficacy of dietary sodium restriction for reducing SBP in some normotensive and hypertensive individuals across the adult age range.11 The greatest reductions in SBP occurred in subjects who reduced dietary sodium intake from a moderate to a low level compared with subjects who reduced sodium intake from a high to a moderate level.11 This is consistent with the present results and previous studies from our laboratory10 in which subjects demonstrated baseline dietary sodium intake comparable to the DASH moderate level and reduced dietary sodium to a low level.
The present findings complement our recent observations in postmenopausal women10 by demonstrating that dietary sodium restriction produces mean reductions in supine resting SBP in middle-aged and older men and women with stage 1 systolic hypertension to high normal levels, while also reducing DBP. Importantly, peak reductions occur within 2 weeks of initiating sodium restriction. We established that significant reductions in SBP and DBP occur under these conditions using both casual (resting) and 24-hour ambulatory recordings. The 24-hour recordings revealed that similar absolute reductions in SBP occurred during the daytime and nighttime hours. We were also able to show that the BP-lowering effects of dietary sodium restriction were independent of other changes in diet composition, metabolic risk profile, and body mass and composition. Thus, these findings establish a rapid and robust primary SBP-lowering effect of dietary sodium restriction in older hypertensive men and women.