Effects of the DASH vs. the Mediterranean Diet Combined With Salt Restriction on Blood Pressure Levels in Adults

September 8, 2023 updated by: Konstantinos Tsioufis, Hippocration General Hospital

Effects of the DASH and the Mediterranean Diet Combined With Salt Restriction on Blood Pressure Levels and Cardiometabolic Risk Factors in Adults With High Normal Blood Pressure or Grade 1 Hypertension: A Randomized Controlled Trial

Non-pharmacological measures should serve as the first-line treatment in individuals with high normal blood pressure (BP) levels or grade 1 hypertension and low-moderate cardiovascular disease risk. Salt intake reduction and the dietary patterns of the Dietary Approaches to Stop Hypertension (DASH) diet and the Mediterranean diet (MedDiet) have been recognized as effective dietary measures for BP reduction. To the best of our knowledge, no clinical trials were designed to compare the effects of these dietary strategies. The purpose of the present trial was to compare the effects of salt restriction, the DASH, and the MedDiet combined with the salt restriction on BP levels and cardiometabolic risk factors in adults with high normal BP or grade 1 hypertension over 3 months.

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

This was a 3-month, single-center, single-blind, randomized, controlled, clinical trial, with 4 parallel groups. Before their randomization, the potential participants visiting the Hypertension Unit of the Hippocration General Hospital of Athens for the first time were assessed for eligibility during two screen visits. Anthropometric measurements, demographic characteristics, dietary intake, physical activity level, smoking history, and alcohol consumption were recorded. In addition, office and ambulatory BP measurements, as well as fasting blood samples and 24-hour urine samples were obtained. Patients were eligible for inclusion if they had high normal BP (office systolic BP: 130-139 mmHg and/or office diastolic BP: 85-89 mmHg) or grade 1 hypertension (office systolic BP: 140-159 mmHg and/or office diastolic BP: 90-99 mmHg), based on the average of the means of the last two out of three measurements made during the two screen visits and were free of antihypertensive drug treatment and major medical conditions. Enrolled patients were blindly randomized to one of the four study groups, i.e., control group (CG), salt restriction group (SRG), DASH diet combined with salt restriction group (DDG), or MedDiet combined with salt restriction group (MDG). After randomization, all patients were followed monthly for 3 months in individual sessions, coordinated by the clinical dietician. For the patients of all four study groups, the goal was to maintain the initial body weight stable. Patients in the CG received the usual advice about salt restriction given to the patients by the clinical dietician at the Hypertension Unit. They were followed at the same frequency as the patients in the other study groups to obtain the study's intended measurements, without any other intervention. For the patients in the three intervention groups, the goal was to limit sodium intake to 2,000 mg/ day. Patients in the SRG were given a detailed booklet containing information about table salt and during each 45-min individual session, they received intensive counselling and training to increase adherence to salt restriction. Patients in the DDG and the MDG received a more extensive booklet, which also contained information about the assigned dietary pattern and an individualized eating plan, while during the 45-min individual sessions, patients in these two intervention groups were intensively counselled and trained to increase adherence to salt restriction and the assigned dietary pattern. Adherence to the assigned diet and/or salt restriction was established through subjective and objective measures, i.e., 7-day food records, adherence scores, and 24-hour urine tests. Anthropometric indices, dietary intake, physical activity level, and office BP were measured at baseline, and during each follow-up visit. Ambulatory BP measurements and collection of fasting blood samples and 24-hour urine samples were conducted at baseline and the end of the 3-month intervention.

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.
240

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

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Greece
      • Athens, Greece, 11527
        • Hypertension Unit, First Cardiology Clinic, Hippocration General Hospital, National and Kapodistrian University of Athens

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

18 years to 65 years (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  1. High normal BP (office systolic BP: 130-139 mmHg and/or office diastolic BP: 85-89 mmHg) or grade 1 hypertension (office systolic BP: 140-159 mmHg and/or office diastolic BP: 90-99 mmHg) and low-moderate 10-year cardiovascular disease risk.
  2. Willingness to participate in a dietary intervention to control BP and to attend individual sessions.
  3. Signed informed consent form for participation.

Exclusion Criteria:

  1. Current use of anti-hypertensive medications.
  2. Current use of any other medications or agents affecting BP levels (e.g., nonsteroidal anti-inflammatory drugs).
  3. Use of food supplements accompanied by a refusal to discontinue them.
  4. Participation in a clinical study involving a drug or device within 3 months of screening.
  5. Active weight loss or participation in a weight loss treatment program within 3 months of screening.
  6. Secondary hypertension.
  7. Atomic history of cardiovascular disease (e.g. acute myocardial infarction, stroke, heart failure).
  8. Diabetes Mellitus (Type 1 & 2).
  9. Chronic kidney disease, defined as an estimated Glomerular Filtration Rate (eGFR) <60 mL/min/1.73m2.
  10. Liver disease (e.g., hepatitis, cirrhosis).
  11. Lung disease (e.g., chronic obstructive pulmonary disease).
  12. Inflammatory bowel disease (e.g., Crohn's disease, ulcerative colitis).
  13. Celiac disease.
  14. Active malignancy or cancer therapy.
  15. Current major psychiatric disorder or current drug abuse.
  16. Body Mass Index >40 kg/m2.
  17. Current alcohol consumption >14 drinks per week.
  18. Current or planned pregnancy before the end of the study, or breast-feeding.
  19. Any concomitant conditions that in the opinion of the investigator interfere with the diet or other situations requiring specific nutritional management.

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

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Triple

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.
No Intervention: Control Group (CG)
Patients continued to consume their usual diet for 3 months
Experimental: Salt Restriction Group (SRG)
Patients continued to consume their usual diet, but they restricted sodium intake to 2,000 mg/ day for 3 months.
Behavioral: Salt Restriction Group (SRG)
Patients assigned to the SRG continued to consume their usual diet, but they had to restrict their sodium intake to 2,000 mg/ day. They were given a detailed booklet containing information about table salt, foods rich in sodium, and practical ways to decrease salt consumption. During each 45-min individual session, they received intensive counselling and training to increase adherence to salt restriction. Also, they were instructed to keep their body weight stable and not to change their physical activity level over the next 3 months.
Experimental: DASH Diet combined with salt restriction Group (DDG)
Patients consumed the DASH diet for 3 months.
Behavioral: DASH Diet combined with salt restriction Group (DDG)
Patients assigned to the DDG received a more extensive booklet, which which in addition to the information regarding salt restriction, contained detailed information about the DASH diet, and practical advice about how to start and stay on the assigned dietary pattern. In addition to the booklet, each patient received an individualized eating plan with six sample daily menus, incorporating the goals of the DASH diet. During the 45-min individual sessions, patients were intensively counselled and trained to increase adherence to salt restriction and the assigned dietary pattern. Also, they were instructed to keep their body weight stable and not to change their physical activity level over the next 3 months.
Experimental: Mediterranean Diet combined with salt restriction Group (MDG)
Patients consumed the MedDiet diet for 3 months.
Behavioral: Mediterranean Diet combined with salt restriction Group (MDG)
Patients assigned to the MDG received a more extensive booklet, which which in addition to the information regarding salt restriction, contained detailed information about the MedDiet, and practical advice about how to start and stay on the assigned dietary pattern. In addition to the booklet, each patient received an individualized eating plan with six sample daily menus, incorporating the goals of the MedDiet diet. During the 45-min individual sessions, patients were intensively counselled and trained to increase adherence to salt restriction and the assigned dietary pattern. Also, they were instructed to keep their body weight stable and not to change their physical activity level over the next 3 months.

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
Measure Description
Time Frame
Office systolic blood pressure (BP)
Time Frame: 3 months post-intervention
The attained mean office systolic BP difference among the randomized arms
3 months post-intervention

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
Measure Description
Time Frame
Office diastolic blood pressure (BP)
Time Frame: 3 months post-intervention
The attained mean office diastolic BP difference among the randomized arms
3 months post-intervention
Ambulatory systolic and diastolic blood pressure (BP)
Time Frame: 3 months post-intervention
The attained between-group differences regarding the mean ambulatory BP measurements (during 24h, daytime, and night-time)
3 months post-intervention
Odds of hypertension
Time Frame: 3 months post-intervention
The odds of hypertension according to the office BP measurements in each study group
3 months post-intervention
Metabolic syndrome and its components
Time Frame: 3 months post-intervention
The attained between-group differences in metabolic syndrome presence and in the presence of individual metabolic syndrome components
3 months post-intervention

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.
Hippocration General Hospital

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: Konstantinos P Tsioufis, Prof., First Cardiology Clinic, Hippocration General Hospital, NKUA

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 (Actual)

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.
January 7, 2019

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.
May 27, 2022

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.
September 9, 2022

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).
December 14, 2022

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.
December 21, 2022

First Posted (Actual)

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.
December 30, 2022

Study Record Updates

Last Update Posted (Actual)

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.
September 13, 2023

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.
September 8, 2023

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.
September 1, 2023

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

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.
  • The DASH-MedDiet study

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

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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