Watermelon Supplementation and Arterial Stiffness

March 17, 2012 updated by: Arturo Figueroa, Florida State University

Effects of Oral L-citrulline/L-arginine in Watermelon on Central Blood Pressure and Arterial Stiffness in Individuals With Obesity-related High Blood Pressure

Increased abdominal obesity (waist circumference) and systolic blood pressure (BP) are main risk factors for the metabolic syndrome. Approximately 60% of adults in the United States are prehypertensive or hypertensive. Hypertension has been associated with abnormal endothelial and autonomic function, the two main mechanisms of BP regulation. Endothelial dysfunction, as a result of reduced NO (a vasodilator), and increased sympathetic nervous system activity contribute to arterial stiffness by enhancing the vasomotor tone. Because BP variations are sensed by baroreceptors in the wall of large arteries, increased stiffness of arteries may attenuate the control of BP by the autonomic nervous system leading to hypertension. High production of proinflammatory cytokines and low adiponectin (vascular protective molecule), are considered the underlying mechanisms leading to endothelial dysfunction and arterial stiffness. The recommended intervention for controlling BP in overweight/obese individuals with pre- and stage 1- hypertension is lifestyle modifications and not drug therapy. Among the dietary regimens that are reported to reduce BP is L-arginine, the substrate for endothelial NO production. Recently, oral L-citrulline has been shown to be more effective than L-arginine in improving circulating NO levels because is not affected by enzymatic degradation. Watermelon, the leading US melon crop, is one of the few natural foods rich in L-citrulline which is efficiently transformed to arginine in humans. The investigators long-term goal is to provide feasible and effective dietary ways to reduce cardiovascular risk factors in individuals with high abdominal fat and BP. The overall objective of this study is to bring forth evidence that watermelon supplementation will reduce BP and cardiovascular risk factors such as arterial stiffness, autonomic dysfunction and endothelial dysfunction. The investigators postulate that watermelon supplementation will reduce BP and arterial stiffness by enhancing endothelial function and reducing vascular inflammation. The findings of this study will provide a foundation for disseminating feasible, safe approaches for preventing and combating obesity-related hypertension at its early stage which does not require drug therapy.

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

The purpose of the study is to examine the effect of 12 weeks of L-citrulline/L-arginine in the form of watermelon supplementation on arterial function and autonomic neural control of the heart rate and blood pressure in older overweight/obese men and women with pre- and stage 1- hypertension. The specific aims of the study are:

  1. To investigate the extent to which daily consumption of watermelon supplementation containing L-citrulline/L-arginine (4/2 g) will reduce BP and arterial stiffness. This aim will examine the working hypothesis that watermelon supplementation will reduce BP and improve arterial function. This aim will be tested by measuring brachial and central (aortic and carotid) BP at rest and during physiological stress (head-up tilt test and cold pressor test), and by evaluating arterial stiffness using pulse wave velocity of the aorta and legs as primary variables.
  2. To determine the effect of watermelon supplementation on endothelial function. There is evidence that watermelon improves endothelial function in rats. Hence, we postulate that watermelon in part exerts its vascular protective effects by modulating indices of endothelial function. This aim will be tested by measuring flow-mediated dilation using vascular ultrasound and circulating levels of vasodilators, vasoconstrictors, and markers of vascular inflammation (adiponectin, leptin, endothelin-1, angiotensin II, prostaglandin F2α, sVCAM-1, sICAM-1, and 8-isoprostane).
  3. To determine whether watermelon supplementation will improve the autonomic control of BP and heart rate in individuals with high abdominal obesity and BP. There is evidence that food high in L-arginine improves baroreflex sensitivity (BRS) in individuals with pre-hypertension. This aim will examine the working hypothesis that watermelon will improve cardiovascular autonomic control of BP by measuring heart rate variability, BP variability and BRS at rest and during physiological stress as secondary variables.

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.
  • Phase 2
  • Phase 1

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
    • Florida
      • Tallahassee, Florida, United States, 32306
        • Cardiovascular Physiology Laboratory

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 70 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Thirty men and women 45-70 years of age
  • BP between 120-159/80-99 mmHg
  • Waist circumference >102 cm in men and > 80 cm in women

Exclusion Criteria:

  • BP >160/100 mmHg
  • Asthma
  • Glaucoma
  • Herpes simplex
  • Uncontrolled diabetes
  • Neurological disease
  • Cardiovascular disease
  • Inflammatory disease
  • Kidney disease
  • Hormone replacement therapy (HRT)
  • Amino acid/vitamin supplementation\
  • Corticosteroids or non-steroidal anti-inflammatory drugs
  • Any drug known to affect BP or heart rate
  • Glycemic control drugs
  • Lipids reducing drugs
  • Participants should not consume > 12 alcoholic drink/week
  • Smokers
  • Regular Exercisers (= 1.5 hour/week).

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: Crossover 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.
Placebo Comparator: Maltodextrin
6g/day of placebo (maltodextrin)
Dietary supplement: Watermelon Extract
6 weeks of watermelon extract taken in two doses of 3g each per day (6g per day)containing L-citrulline/L-arginine (4/2 g)
Other Names:
  • Watermelon extract from Milne fruit Products Inc
Experimental: Watermelon
(6g per day)containing L-citrulline/L-arginine (4/2 g)
Dietary supplement: Watermelon Extract
6 weeks of watermelon extract taken in two doses of 3g each per day (6g per day)containing L-citrulline/L-arginine (4/2 g)
Other Names:
  • Watermelon extract from Milne fruit Products Inc

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
Blood Pressure
Time Frame: 12 weeks
By measuring brachial and central (aortic and carotid) BP at rest and during physiological stress (head-up tilt test and cold pressor test)
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
Arterial Stiffness
Time Frame: 12 weeks
Using pulse wave velocity of the aorta and legs.
12 weeks
Endothelial function
Time Frame: 12 weeks
By measuring flow-mediated dilation using vascular ultrasound and circulating levels of vasodilators, vasoconstrictors, and markers of vascular inflammation (adiponectin, leptin, endothelin-1, angiotensin II, prostaglandin F2α, sVCAM-1, sICAM-1, and 8-isoprostane).
12 weeks
Autonomic control of BP
Time Frame: 12 weeks
By measuring BP variability and BRS at rest and during physiological stress
12 weeks
Autonomic control of heart rate
Time Frame: 12 weeks
By measuring heart rate variability at rest and during physiological stress
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.
Florida State University

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: Arturo Figueroa, MD, PhD, The Florida 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

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.
August 1, 2010

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.
August 1, 2011

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.
August 1, 2011

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).
August 17, 2010

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.
August 18, 2010

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.
August 19, 2010

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.
March 20, 2012

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.
March 17, 2012

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.
March 1, 2012

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.
  • RF02032

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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