Mechanism of the Blood Pressure Lowering Effect of the DASH Dietary Pattern

April 9, 2013 updated by: Duke University
Understanding the possible mechanism(s) by which the DASH dietary pattern lowers blood pressure will potentially enhance the value of this dietary intervention by elucidating the conditions under which it will be most effective, identifying target populations, examining its impact on vascular health beyond blood pressure, and enhancing the investigators' understanding of the interactions among diet, blood pressure and vascular function. In addition, results of this study may help to identify additional therapeutic targets. Therefore, the overall goal of the proposed study is to determine the mechanism(s) by which the DASH dietary pattern lowers blood pressure by using a controlled feeding design.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Randomized, controlled feeding trials have established the BP lowering effects of the Dietary Approaches to Stop Hypertension (DASH) dietary pattern, which emphasizes fruits, vegetables and low fat dairy and is low in saturated and total fat. The DASH studies were designed to establish efficacy, not to determine mechanism of action. Other studies suggest that the DASH diet may have effects on the renin-angiotensin-aldosterone system (RAAS). These effects have not been directly evaluated, nor have other potential mechanisms of action such as effects on adrenergic tone, vascular function and inflammation. The BP-lowering effect of the DASH dietary pattern was maximal after two weeks of controlled feeding, and was comparable in magnitude to antihypertensive medication among participants with stage 1 hypertension. Understanding the possible mechanism(s) by which the DASH diet lowers BP will potentially enhance the value of this intervention by elucidating the conditions under which it will be most effective, identifying target populations, examining its impact on vascular health beyond BP, and enhancing our understanding of the interactions among diet, BP and vascular function. In addition, results of this study may help to identify additional therapeutic targets. Therefore, the overall goal of the proposed study is to determine the mechanism(s) by which the DASH diet lowers BP. Our unifying hypothesis is that DASH diet lowers BP through effects on vascular function and sodium excretion, mediated through the effects on RAAS.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
20

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

22 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Description

Inclusion Criteria:

  1. SBP 140-159 mm Hg and DBP 90-99 mm Hg based on mean values over two screening visits,
  2. Age ≥22 years, and
  3. Willing to eat at least one on-site meal/day, five days/week, and willing to eat study diets and nothing else for the 3 weeks of controlled feeding.

Exclusion Criteria:

  1. Any serious illness that would interfere with participation or make DASH diet unsafe to the participants,
  2. Currently on cancer chemotherapy or with evidence of active malignancy or radiation therapy within past six months,
  3. History of CVD event (MI, CABG, angioplasty, symptomatic ischemic heart disease, or stroke),
  4. Clinical diagnosis of congestive heart failure,
  5. Current diagnosis of diabetes and treatment for diabetes with oral medication or insulin,
  6. Body mass index > 45 Kg/m2,
  7. DASH MECHANISM staff or household member of DASH MECHANISM staff,
  8. Using Medications including BP lowering drugs within the last three months, using lithium,insulin or oral diabetes medications, oral corticosteroids, unstable doses of psychotropics or phenothiazines, antacids or nutritional supplements unless they can be discontinued, or weight reducing medications;
  9. Consumption of more than 14 alcoholic drinks per week;
  10. Investigator discretion for safety or compliance reasons;
  11. Inability to provide reliable BP & vascular functions measurements;
  12. Planning to leave the area prior to the anticipated end of the intervention period;
  13. Pregnant, planning a pregnancy prior to the end of intervention, or breast feeding;
  14. Significant food allergies, preferences, or dietary requirements that would interfere with diet adherence; and
  15. Subjects taking medications for erectile dysfunction.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: DASH
The Dietary Approaches to Stop Hypertension Dietary pattern.
Other: DASH, Control
controlled feeding of either the DASH dietary pattern or a typical American diet at isocaloric level.
Experimental: Control
The typical American diet as estimated from the NHANES survey.
Other: DASH, Control
controlled feeding of either the DASH dietary pattern or a typical American diet at isocaloric level.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Time Frame
urinary sodium
Time Frame: 2 weeks
2 weeks

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Time Frame
blood pressure
Time Frame: 2 weeks
2 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Duke University

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
American Heart Association

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Pao-Hwa Lin, PhD, Duke University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
July 1, 2007

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
June 1, 2009

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
June 1, 2009

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
November 19, 2009

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 19, 2009

First Posted (Estimate)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
November 20, 2009

Study Record Updates

Last Update Posted (Estimate)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
April 11, 2013

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 9, 2013

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
November 1, 2009

More Information

Terms related to this study

Keywords

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • Pro00001236
  • AHA 0755460U (Other Identifier: AHA)

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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