Effectiveness of the DASH Diet at Reducing High Blood Pressure

This study is ongoing, but not recruiting participants.
Sponsor:
Collaborator:
Information provided by (Responsible Party):
Paul Conlin, MD, Brigham and Women's Hospital
ClinicalTrials.gov Identifier:
NCT00123006
First received: July 20, 2005
Last updated: July 18, 2014
Last verified: July 2014
  Purpose

The purpose of this study is to test the effects of the DASH diet in patients with isolated systolic hypertension.


Condition Intervention
Cardiovascular Diseases
Hypertension
Heart Diseases
Behavioral: Dietary Approaches to Stop Hypertension (DASH)
Behavioral: Control Diet

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor)
Primary Purpose: Prevention
Official Title: Cardiovascular and Renal Hemodynamics and the DASH Diet

Resource links provided by NLM:


Further study details as provided by Brigham and Women's Hospital:

Primary Outcome Measures:
  • Changes in central aortic stiffness, diastolic relaxation, renal blood flow,and vascular response to Ang II [ Time Frame: Measured at 4 weeks ] [ Designated as safety issue: No ]

Estimated Enrollment: 55
Study Start Date: January 2006
Estimated Study Completion Date: October 2014
Primary Completion Date: June 2009 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Active Comparator: 1
Dietary Approaches to Stop Hypertension (DASH)
Behavioral: Dietary Approaches to Stop Hypertension (DASH)
4 week feeding intervention
Placebo Comparator: 2
Control diet
Behavioral: Control Diet
4 week feeding intervention

Detailed Description:

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.

  Eligibility

Ages Eligible for Study:   20 Years and older
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   No
Criteria

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
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00123006

Sponsors and Collaborators
Brigham and Women's Hospital
Investigators
Principal Investigator: Paul R. Conlin, MD Brigham and Women's Hospital
  More Information

No publications provided

Responsible Party: Paul Conlin, MD, Principal Investigator, Brigham and Women's Hospital
ClinicalTrials.gov Identifier: NCT00123006     History of Changes
Other Study ID Numbers: 229, R01HL077234, R01 HL77234
Study First Received: July 20, 2005
Last Updated: July 18, 2014
Health Authority: United States: Federal Government

Additional relevant MeSH terms:
Cardiovascular Diseases
Heart Diseases
Hypertension
Vascular Diseases

ClinicalTrials.gov processed this record on October 22, 2014