The Effects of Sodium Reduction and the DASH Diet on Ambulatory Blood Pressure: Overall and Race-Stratified Results from the DASH-Sodium Trial

Background On average, Black adults compared to White adults have higher ambulatory blood pressure (ABP), particularly during sleep. Methods Participants were randomly assigned to eat a control diet or the DASH diet (n = 335 with ABP, 58% self-reported Black). On their assigned diet, participants had three, randomly ordered, 30-day feeding periods with different sodium levels (low, intermediate, and high). ABP was obtained at the end of each period. Results Compared to the control diet with high sodium (reference), reducing sodium and consuming the DASH diet, alone or combined, significantly lowered 24-hour, awake, and asleep systolic and diastolic ABP in Black and Non-Black participants. The DASH diet with low sodium reduced mean (95%CI) awake SBP by 9.0mmHg (6.4, 11.7) in Black participants and 7.5mmHg (4.5, 10.6) in Non-Black participants, and mean asleep SBP by 8.0mmHg (4.8, 11.2) in Black participants and 7.4mmHg (3.9,11.0) in Non-Black participants in comparison to the reference (each P < .05). Despite reductions in asleep ABP from the DASH diet and sodium reduction, significant differences by race persisted in achieved ABP, consistently so for asleep ABP. Mean±SE achieved levels of asleep SBP on the control diet with high sodium were 124.1 ± 0.6mmHg in Black participants and 120.2 ± 0.7mmHg in Non-Black participants (P < .005), while on the DASH diet with low sodium, achieved levels were 115.2 ± 0.5mmHg in Black participants and 112.5 ± 0.7mmHg in Non-Black participants (P < .005). Conclusions Despite clinically relevant reductions in ABP from sodium reduction and the DASH diet in both Black and Non-Black participants, racial differences in achieved levels of asleep ABP persisted.