Effects of dietary patterns and sodium intake on blood pressure variability: results from the DASH and DASH-sodium...

In observational studies, blood pressure (BP) variability has been independently associated with adverse cardiovascular disease outcomes. The Dietary Approaches to Stop Hypertension (DASH) diet and sodium reduction lower BP and cardiovascular risk, but their effects on BP variability (BPV) are uncertain.

This study assessed the effects of dietary patterns (DASH vs. Control) and sodium intake (higher vs. lower) on BPV, using both office and 24-h ambulatory BP measurements in the DASH and DASH-Sodium trials. In primary analyses, week-to-week office BPV and 24-h ambulatory BPV were quantified using variation independent of the mean (VIM). Between-group comparisons were performed using t-tests; interactive effects between dietary patterns and sodium intake were assessed using multivariate linear regression models.

In pooled analyses of both trials, there was no difference in week-to-week systolic BPV (difference in systolic VIM: 0.49, 95% CI -0.05-1.03) or 24-h systolic BPV (difference in systolic VIM: 0.37, 95% CI -0.13-0.87) between the DASH and Control diet groups. In the DASH-Sodium trial, VIM at higher and lower sodium levels did not differ (e.g. difference in VIM for week-to-week systolic BP: 0.31, 95% CI -0.10-0.72). No significant combined or interactive effects of diet and sodium level on BPV were observed.

While the DASH diet and reduced sodium intake lower absolute BP levels, these dietary interventions do not significantly affect BPV. These findings suggest that the BP-related benefits of the DASH diet and sodium reduction likely result from reducing absolute BP rather than reducing BPV.