DASH Diet Evidence


Major Statistical Significant Clinical Trials and Outcomes


We highlight the 3 most statistical significant clinical trials that show Evidence for the DASH Diet

1. “A Clinical Trial of the Effects of Dietary Patterns on Blood Pressure”. Appel et al. (1997) (The original DASH trial)

  • Design: Multicenter, randomized, outpatient feeding trial
  • Participants: 459 adults (untreated), some with hypertension, some without. -Interventions: Three diets for 8 weeks each, after a 3-week run-in on the control diet. The arms were:
    1. Control diet (typical American diet)
    2. Fruits & vegetables diet
    3. Combination diet (fruits, vegetables, low-fat dairy, and reduced saturated fat, total fat, and cholesterol) Key findings:
  • In people with hypertension, the combination diet reduced systolic blood pressure by about 11.4 mm Hg more than the control diet; diastolic by ~5.5 mm Hg.
  • In people without hypertension, reductions were smaller: ~3.5 mm Hg (systolic) and ~2.1 mm Hg (diastolic). Significance: This trial showed that the full “DASH combination diet” (not just fruits & veg) has clinically meaningful BP-lowering effects, even without changing weight or sodium.

2. “Effects on Blood Pressure of Reduced Dietary Sodium and the Dietary Approaches to Stop Hypertension (DASH) Diet” — Sacks FM et al. (2001) (The DASH-Sodium trial) New England Journal of Medicine

  • Design: Multicenter randomized trial using crossover for sodium levels, feeder to test both diet pattern (Control vs DASH) and sodium intake levels.
  • Participants: Adults with elevated blood pressure (either “higher than optimal” or stage 1 hypertension). Interventions:
  • Two dietary patterns: Control diet vs DASH diet (rich in fruits, vegetables, low-fat dairy, reduced red meat, sweets, etc.).
  • Within each dietary pattern, three sodium levels (high, intermediate, low), each for 30 days in random order. New England Journal of Medicine Key findings:
  • Both reducing sodium and following the DASH diet each lower blood pressure; combining them gives the largest effects.
  • For example, comparing the DASH diet at the low sodium level vs the control diet at the high sodium level:
    • Hypertensive participants had ~11.5 mm Hg lower systolic BP.
    • Non-hypertensive participants also had significant reductions (~7.1 mm Hg).

Significance: Demonstrates that sodium reduction augments the effect of DASH, and that both lifestyle (diet pattern) and nutrient content (sodium) are important.

3. ENCORE Trial: “Effects of the DASH Diet Alone and in Combination With Exercise and Weight Loss on Blood Pressure…” Blumenthal JA et al. (2010)

  • Design: Randomized controlled trial, 3 arm design.
  • Participants: Overweight or obese adults with high blood pressure, not on antihypertensive medication.
  • Interventions:
    1. Usual care/control diet
    2. DASH diet only (no weight loss, no formal exercise intervention)
    3. DASH diet + behavioral weight management + exercise
  • Duration: Four months. Key findings:
  • The DASH + weight-management (exercise + caloric restriction) arm had the greatest blood pressure reduction: about 12.5/5.9 mm Hg (systolic/diastolic) net benefit vs control.
  • The DASH diet alone (without weight loss/exercise) still had significant reductions: ~7.7/3.6 mm Hg compared to control. Significance: Shows the additive (or synergistic) benefit of combining diet with weight loss and exercise, especially in overweight/obese people with elevated BP.