Blueberries for Improving Vascular Endothelial Function in Postmenopausal Women With Elevated Blood Pressure

September 9, 2022 updated by: Sarah Johnson, Colorado State University

Blueberry Consumption for Improving Vascular Endothelial Dysfunction in Postmenopausal Women With Elevated Blood Pressure and Stage 1-Hypertension

Postmenopausal women are at an increased risk of developing cardiovascular disease (CVD) largely due to accelerated aging-related modifications to vascular health following menopause. The vascular endothelium is responsible for producing chemicals that are essential for proper vasodilation and blood flow and therefore is involved in maintaining normal blood pressure. A major modification that occurs during aging and is accelerated during menopause is termed vascular endothelial dysfunction which is characterized by impaired endothelium-dependent dilation. This can lead to increased blood pressure, atherosclerosis, and increased risk of CVD and death. Nitric oxide (NO) is a chemical produced by the endothelium and is essential for normal endothelial function and cardiovascular health. Vascular endothelial dysfunction is primarily caused by reduced NO bioavailability secondary to excessive oxidative stress. Approximately 3/4 of postmenopausal women have elevated blood pressure or hypertension which further worsens endothelial function and increases CVD risk through increased oxidative stress and inflammation. Blueberries are rich in phytochemicals including anthocyanins, phenolic acids, and pterostilbene. These phytochemicals and their metabolites are known to attenuate oxidative stress and inflammation. The overall goal of the current study is to assess the efficacy of blueberries to improve vascular endothelial dysfunction in this high-risk population and to gain insight into underlying mechanisms. 58 postmenopausal women with elevated blood pressure and stage 1-HTN will be asked to consume 22 grams freeze-dried blueberry powder or placebo powder per day for 12 weeks. Vascular endothelial function will be assessed at baseline and 12 weeks. Measurements indicative of vascular nitric oxide production, oxidative stress, inflammation, cardiometabolic health, cognitive function, and blueberry phytochemical metabolism will be measured at baseline and 12 weeks. Blood pressure will be assessed at baseline and 4, 8, and 12 weeks.

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.

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.
43

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

  • United States
    • Colorado
      • Fort Collins, Colorado, United States, 80523-1571
        • Department of Food Science and Human Nutrition, Colorado State University

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

45 years to 65 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

Female

Description

Inclusion Criteria:

  • Aged 45-65 years
  • Postmenopausal women (≥ 1 years postmenopausal; natural or surgical menopause; confirmed by measurement of estradiol at a level < 30 pg/mL and follicle-stimulating hormone at a level ≥ 30 mIU/mL)
  • Elevated or stage 1-HTN (confirmed as resting seated systolic blood pressure < 120 or ≥ 139 mmHg and/or a diastolic blood pressure ≥ 90 mmHg using an average of 3 measurements, on 2 separate occasions - screening and baseline visits)
  • Ability to provide informed consent

Exclusion Criteria:

  • Systolic blood pressure < 120 or ≥ 139 mm Hg and/or diastolic blood pressure ≥ 90 mmHg
  • Taking > 1 antihypertensive medication and/or taking the antihypertensive medication for < 3 months
  • Diagnosed cancer, cardiovascular disease, diabetes, or gastrointestinal, kidney, liver, and/or pancreatic disease
  • Triglycerides > 350 mg/dL, low-density lipoprotein cholesterol (LDL-C) ≥ 190 mg/dL, and/or taking a lipid-lowering medication
  • Hormone replacement therapy use 6 months prior to study start
  • Taking phosphodiesterase-5 inhibitors
  • Weight change ≥ 3 kg in the past 3 months, actively trying to lose weight, or unwilling to remain weight stable throughout the study
  • Current smokers or history of smoking in the past 12 months
  • Binge and/or heavy drinker (>3 drinks on any given occasion and/or >7 drinks/week for women, and >4 drinks on any given occasion and/or >14 drinks/week for men)
  • Body mass index < 18.5 or > 40 kg/m2
  • Active infection or antibiotic therapy
  • Allergies or contraindication to study treatments, pharmacological agents, or procedures

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: Treatment
  • 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.
Experimental: Blueberry
22 g/day freeze-dried blueberry powder for 12 weeks
Dietary supplement: Blueberry Powder
22 g/day freeze-dried blueberry powder for 12 weeks
Placebo Comparator: Control
22 g/day placebo powder for 12 weeks
Dietary supplement: Placebo Powder
22 g/day placebo powder for 12 weeks

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
Endothelium-dependent dilation
Time Frame: Baseline to 12 Weeks
Assessed as brachial artery flow-mediated dilation in a study subset of participants
Baseline to 12 Weeks
Blood pressure
Time Frame: Baseline to 12 weeks
Assessed using an automated blood pressure monitor (SphgmoCor)
Baseline to 12 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
Measure Description
Time Frame
Vascular oxidative stress
Time Frame: Baseline and 12 weeks
Change in brachial artery flow-mediated dilation following acute infusion of ascorbic acid (a dose known to scavenge superoxide) as an index of vascular oxidative stress in a study subset of participants
Baseline and 12 weeks
Endothelial cell nitric oxide production, oxidative stress, and inflammation
Time Frame: Baseline and 12 weeks
Protein expression markers will be measured by quantitative immunofluorescence in biopsied venous endothelial cells in a study subset of participants
Baseline and 12 weeks
Systemic markers of cardiometabolic health
Time Frame: Baseline and 12 weeks
Circulating markers of lipid and glucose metabolism, nitric oxide, and inflammation
Baseline and 12 weeks
Plasma blueberry polyphenol metabolites
Time Frame: Baseline and 12 weeks
Targeted analysis of plasma metabolites by GC-MS and LC-MS
Baseline and 12 weeks
Endothelium-independent dilation
Time Frame: Baseline to 12 weeks
Assessed as brachial artery diameter responses to sublingual nitroglycerin in a study subset of participants
Baseline to 12 weeks
Augmentation index
Time Frame: Baseline to 12 weeks
Arterial stiffness assessed as augmentation index using the SphygmoCor XCEL
Baseline to 12 weeks
Pulse wave velocity
Time Frame: Baseline to 12 weeks
Arterial stiffness assessed as carotid-femoral pulse wave velocity using the SphygmoCor XCEL
Baseline to 12 weeks
Gut microbiota
Time Frame: Baseline to 12 weeks
Determine the effects on stool sample microbial populations
Baseline to 12 weeks

Other Outcome Measures

Other Outcome Measures

For clinical trials, a planned measurement described in the protocol that is used to determine the effect of an intervention/treatment on participants. For observational studies, a measurement or observation that is used to describe patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Types of outcome measures include primary outcome measure and secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Processing speed
Time Frame: Baseline and 12 weeks
Exploratory measures assessed using the NIH Cognitive Toolbox iPad app
Baseline and 12 weeks
Language
Time Frame: Baseline and 12 weeks
Exploratory measures assessed using the NIH Cognitive Toolbox iPad app
Baseline and 12 weeks
Working memory
Time Frame: Baseline and 12 weeks
Exploratory measures assessed using the NIH Cognitive Toolbox iPad app
Baseline and 12 weeks
Executive function and attention
Time Frame: Baseline and 12 weeks
Exploratory measures assessed using the NIH Cognitive Toolbox iPad app
Baseline and 12 weeks
Episodic memory
Time Frame: Baseline and 12 weeks
Exploratory measures assessed using the NIH Cognitive Toolbox iPad app
Baseline and 12 weeks
Peripheral blood mononuclear cell inflammation and oxidative stress
Time Frame: Baseline and 12 weeks
Exploratory measures analyzed by gene expression
Baseline and 12 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.
Colorado State 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.
U.S. Highbush Blueberry Council

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: Sarah A. Johnson, PhD, RDN, Department of Food Science and Human Nutrition, Colorado State University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Helpful Links

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.
December 2, 2017

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.
September 30, 2021

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 30, 2021

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 2, 2017

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 7, 2017

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 13, 2017

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 14, 2022

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 9, 2022

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, 2022

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.
  • 1255927

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

product manufactured in and exported from the U.S.

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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