Effects on blood pressure of reduced dietary sodium and the Dietary Approaches to Stop Hypertension (DASH) diet. DASH-Sodium Collaborative Research Group.
Level 2 - randomized trial
Multicenter randomized controlled trial
PubMed 11136953 · doi:10.1056/NEJM200101043440101
What was done
A total of 412 participants with and without hypertension were randomly assigned to either a control diet typical of US intake or the DASH diet (rich in vegetables, fruits, and low-fat dairy). Within their assigned diet group, participants ate foods containing high, intermediate, and low levels of sodium for 30 consecutive days each in a randomized crossover sequence. Systolic blood pressure responses were evaluated across sodium levels, diet assignments, and demographic subgroups.
What was found
Reducing sodium intake from high to intermediate lowered systolic blood pressure by 2.1 mm Hg (P<0.001) on the control diet and by 1.3 mm Hg (P=0.03) on the DASH diet. Reducing sodium from intermediate to low led to further reductions of 4.6 mm Hg on the control diet (P<0.001) and 1.7 mm Hg on the DASH diet (P<0.01). The DASH diet resulted in significantly lower systolic blood pressure at each sodium level compared with control. Compared with the high-sodium control diet, the low-sodium DASH diet lowered mean systolic blood pressure by 7.1 mm Hg in non-hypertensive participants and by 11.5 mm Hg in hypertensive participants. Effects occurred across hypertension status, race (Black participants and those of other races), and sex.
Why it matters
This study provides definitive randomized evidence that reducing dietary sodium and following the DASH diet lower blood pressure independently and additively. The combined approach produces clinically meaningful reductions in systolic blood pressure in both normotensive and hypertensive individuals.
Limits
Each sodium phase lasted only 30 days, so long-term sustainability and clinical cardiovascular endpoints were not assessed. The abstract does not specify the exact milligram or millimole amounts for the sodium tiers or report diastolic blood pressure data. Provided-food trials may not reflect adherence rates in self-directed, free-living populations.