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A clinical trial of the effects of dietary patterns on blood pressure (DASH feeding trial)

Randomised feeding study (n=459): the DASH ‘combination’ diet lowered systolic/diastolic blood pressure by 5.5/3.0 mmHg more than a typical Western control diet overall, with 11.4/5.5 mmHg larger reductions among hypertensive participants.

Design

  • n = 459 adults with SBP <160 mmHg and DBP 80–95 mmHg
  • 3 wk run-in control diet → 8 wk randomised diets: control, fruits+vegetables, or DASH combination (high produce + low-fat dairy, reduced saturated/total fat)
  • Sodium and weight held constant (isolated diet-composition signal)

Headline BP differences vs control at 8 weeks

  • DASH combination: −5.5 / −3.0 mmHg SBP/DBP (P < 0.001 each)
  • Fruits + vegetables: −2.8 / −1.1 mmHg SBP/DBP (DBP P = 0.07)
  • Hypertensive subgroup (n = 133): DASH combination −11.4 / −5.5 mmHg vs control (P < 0.001)

Evidence hygiene

Feeding-study adherence is high versus free-living counselling trials—pair with Filippou 2020 meta-analysis and PREMIER / ENCORE-style counselling RCTs in Cochrane syntheses for community effect sizes.

Publication

Appel LJ, Moore TJ, Obarzanek E, et al.; DASH Collaborative Research Group. N Engl J Med. 1997 Apr 17;336(16):1117-24. PMID 9099655.

Outcomes

  • Systolic Blood Pressure
    -5.5
    mmHg (Millimetres of Mercury)
  • Diastolic Blood Pressure
    -3
    mmHg (Millimetres of Mercury)
  • Hypertensive subgroup (n=133): DASH combination diet reduced SBP/DBP by 11.4/5.5 mmHg more than control (P<0.001 each); normotensive subgroup −3.5/−2.1 mmHg SBP/DBP.
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