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Watermelon Supplementation and Arterial Stiffness

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ClinicalTrials.gov Identifier: NCT01185041
Recruitment Status : Completed
First Posted : August 19, 2010
Last Update Posted : March 20, 2012
Sponsor:
Information provided by (Responsible Party):
Arturo Figueroa, Florida State University

Brief Summary:
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.

Condition or disease Intervention/treatment Phase
Hypertension Dietary Supplement: Watermelon Extract Phase 1 Phase 2

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.

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 20 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double (Participant, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: Effects of Oral L-citrulline/L-arginine in Watermelon on Central Blood Pressure and Arterial Stiffness in Individuals With Obesity-related High Blood Pressure
Study Start Date : August 2010
Actual Primary Completion Date : August 2011
Actual Study Completion Date : August 2011

Resource links provided by the National Library of Medicine


Arm Intervention/treatment
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 Name: 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 Name: Watermelon extract from Milne fruit Products Inc




Primary Outcome Measures :
  1. 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)


Secondary Outcome Measures :
  1. Arterial Stiffness [ Time Frame: 12 weeks ]
    Using pulse wave velocity of the aorta and legs.

  2. 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).

  3. Autonomic control of BP [ Time Frame: 12 weeks ]
    By measuring BP variability and BRS at rest and during physiological stress

  4. Autonomic control of heart rate [ Time Frame: 12 weeks ]
    By measuring heart rate variability at rest and during physiological stress



Information from the National Library of Medicine

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Ages Eligible for Study:   45 Years to 70 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Criteria

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).

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT01185041


Locations
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United States, Florida
Cardiovascular Physiology Laboratory
Tallahassee, Florida, United States, 32306
Sponsors and Collaborators
Florida State University
Investigators
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Principal Investigator: Arturo Figueroa, MD, PhD The Florida State University
Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
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Responsible Party: Arturo Figueroa, Associate Professor, Florida State University
ClinicalTrials.gov Identifier: NCT01185041    
Other Study ID Numbers: RF02032
First Posted: August 19, 2010    Key Record Dates
Last Update Posted: March 20, 2012
Last Verified: March 2012
Keywords provided by Arturo Figueroa, Florida State University:
Arterial Stiffness
Wave Reflection
Watermelon Supplementation
Aortic Blood Pressure
Obesity
Additional relevant MeSH terms:
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Hypertension
Vascular Diseases
Cardiovascular Diseases