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Effectiveness of the DASH Diet at Reducing High Blood Pressure

This study has been completed.
Sponsor:
ClinicalTrials.gov Identifier:
NCT00123006
First Posted: July 22, 2005
Last Update Posted: January 13, 2016
The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
Collaborator:
National Heart, Lung, and Blood Institute (NHLBI)
Information provided by (Responsible Party):
Paul Conlin, MD, Brigham and Women's Hospital
July 20, 2005
July 22, 2005
January 13, 2016
January 2006
June 2009   (Final data collection date for primary outcome measure)
Changes in central aortic stiffness, diastolic relaxation, renal blood flow,and vascular response to Ang II [ Time Frame: Measured at 4 weeks ]
Not Provided
Complete list of historical versions of study NCT00123006 on ClinicalTrials.gov Archive Site
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Effectiveness of the DASH Diet at Reducing High Blood Pressure
Cardiovascular and Renal Hemodynamics and the DASH Diet
The purpose of this study is to test the effects of the DASH diet in patients with isolated systolic hypertension.

BACKGROUND:

The study expands upon the findings of the Dietary Approaches to Stop Hypertension (DASH) study, which showed that a dietary pattern emphasizing fruits, vegetables, and low fat dairy products and overall reduced in total and saturated fat significantly lowers blood pressure (BP). The DASH diet is particularly effective in African Americans and in individuals with systolic hypertension. However, it is not known if the DASH diet affects the pathophysiology of the hypertensive process. Preliminary data support the possibility that the DASH diet interrupts the renin-angiotensin system. This raises the intriguing possibility that the DASH diet will favorably impact on cardiovascular and renal hemodynamics in patients with isolated systolic hypertension. Therefore, the central hypothesis of this study is that the DASH diet affects central aortic stiffness, diastolic relaxation, and renal and vascular reactivity to angiotensin II (Ang II) by lowering tissue renin-angiotensin system activity.

DESIGN NARRATIVE:

A randomized, crossover design will be used to compare the DASH diet to a control diet as defined in the original DASH protocol (NEJM 1997; 336:1117). Fifty-five community-dwelling individuals age 20 and older with systolic blood pressure (SBP) 140-179 mmHg and diastolic blood pressure (DBP) less than 90 mmHg will enter a 1-week run-in period eating both the control and DASH diets for 3-4 days each. Following this, participants will begin two 4-week intervention feeding periods receiving either the DASH diet or the control diet in random order. Clinical measurements will be taken at the conclusion of each 4-week feeding period.

Outcome measures: Specific measurements will include peripheral and renal vascular response to Ang II infusions, renal blood flow measured by para-aminohippurate (PAH) clearance, conduit vessel hemodynamics, and tissue Doppler imaging (TDI). At the end of each intervention feeding period, the clinical measurements will be made before and after acute administration of captopril, an angiotensin converting enzyme (ACE) inhibitor.

The study will test whether the DASH diet (1) lowers central aortic stiffness as measured by vascular impedance and carotid-femoral pulse wave velocity; (2) improves diastolic relaxation as measured by early diastolic myocardial velocities across the mitral valve (Ea); (3) vasodilates renal blood flow and enhances vascular responses to Ang II; and (4) affects central aortic stiffness, diastolic relaxation, renal blood flow, and renal and vascular reactivity to Ang II by altering target tissue responsiveness to Ang II similar to ACE inhibition.

Interventional
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Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary Purpose: Prevention
  • Cardiovascular Diseases
  • Hypertension
  • Heart Diseases
  • Behavioral: Dietary Approaches to Stop Hypertension (DASH)
    4 week feeding intervention
  • Behavioral: Control Diet
    4 week feeding intervention
  • Active Comparator: 1
    Dietary Approaches to Stop Hypertension (DASH)
    Intervention: Behavioral: Dietary Approaches to Stop Hypertension (DASH)
  • Placebo Comparator: 2
    Control diet
    Intervention: Behavioral: Control Diet
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*   Includes publications given by the data provider as well as publications identified by ClinicalTrials.gov Identifier (NCT Number) in Medline.
 
Completed
44
October 2014
June 2009   (Final data collection date for primary outcome measure)

Inclusion Criteria:

  • Isolated systolic hypertension: systolic blood pressure (SBP) in the range of 140-179 mm Hg and diastolic blood pressure (DBP) less than 90 mm Hg
  • Body mass index (BMI) less than 40
  • Current use of fewer than two blood pressure medications (which will be withdrawn prior to study)

Exclusion Criteria:

  • Major concomitant diseases that may include but are not limited to active pulmonary disease within the past 6 months
  • History of cardiovascular disorders such as angina, heart attack, heart failure, or stent placement
  • Active gastrointestinal disease, including prior gastrointestinal surgery
  • Renal disease with serum creatinine greater than 1.5 mg/dl (men) or 1.4 mg/dl (women)
  • Insulin-dependent diabetes mellitus
  • Current pregnancy
Sexes Eligible for Study: All
20 Years to 80 Years   (Adult, Senior)
No
Contact information is only displayed when the study is recruiting subjects
Not Provided
United States
 
NCT00123006
229
R01HL077234 ( U.S. NIH Grant/Contract )
Yes
Not Provided
Not Provided
Paul Conlin, MD, Brigham and Women's Hospital
Brigham and Women's Hospital
National Heart, Lung, and Blood Institute (NHLBI)
Principal Investigator: Paul R. Conlin, MD Brigham and Women's Hospital
Brigham and Women's Hospital
January 2016

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP