Effect of Watermelon on Gut and Cardiometabolic Health

April 8, 2026 updated by: Ravi Nagpal, Florida State University

Effect of Daily Fresh Watermelon Consumption on Gut and Cardiometabolic Health in Young Adults With Overweight and Obesity

The goal of this clinical trial is to evaluate the effect of daily fresh watermelon consumption for 6-weeks on gut health, including microbiome diversity, gut barrier and immune function in young adults with overweight and obesity. The main questions it aims to answer are:

  1. Will consuming fresh watermelon daily for 6-weeks will improve intestinal barrier health and increase microbiome diversity such as an increased population of beneficial 'probiotic' bacteria when compared to control participants consuming a low-fat snack?
  2. Will consuming fresh watermelon daily for six-weeks will improve other health measures, including body-composition, blood pressure, blood vessel function, blood lipid profiles, and measures of inflammation, as compared to control participants consuming a low-fat snack for the same time period?

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

36

Phase

  • 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 Contact

  • Name: Ravinder Nagpal, PhD
  • Phone Number: 850-644-1829
  • Email: rnagpal@fsu.edu

Study Contact Backup

Study Locations

  • United States
    • Florida
      • Tallahassee, Florida, United States, 32306
        • Recruiting
        • Florida State University - Gut Biome Lab
        • Contact:
        • Principal Investigator:
          • Ravinder Nagpal, PhD
        • Sub-Investigator:
          • Cole Patoine, MS
        • Sub-Investigator:
          • Saiful Singar, MS
        • Sub-Investigator:
          • Andrea Lobene, PhD
        • Sub-Investigator:
          • Joseph Watso, PhD

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

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Between 18 and 30 years old
  • Ability to speak and read in English
  • Overweight or Obese Class 1 and 2 (BMI ≥ 25 - 39.9 kg/m2)

Exclusion Criteria:

  • Intake of antibiotics in the last 3 months
  • Intake of pre/pro/postbiotics in the last 3 months
  • Current or past (within the last 6 months) user of tobacco, marijuana, or E-cigarette products
  • Cardiovascular disease (will not exclude for hypertension), gastrointestinal disease (ulcerative colitis, celiac, Crohn's disease, diverticulosis, peptic ulcers, small intestinal bacterial overgrowth, short bowel syndrome), neurological (multiple sclerosis, meningitis, recent stroke) or endocrine disorders (uncontrolled thyroid disorders, growth hormone disorders, adrenal gland disorders, uncontrolled diabetes - A1C greater than 9%).
  • Food allergy to study foods
  • Any allergy to melon
  • Any allergy to the isocaloric snack (gluten)
  • Regular consumption of watermelon greater than 2 servings / week
  • Current heavy alcohol use (≥ 15 drinks / week for men, ≥ 8 drinks / week for women
  • Class 3 Obesity (BMI > 40 kg/m2)
  • Current user of Citrulline, Arginine, Nitric Oxide or other supplements known to affect nitric oxide synthesis (beet root juice or any beet supplement, Pycnogenol / Pine bark extract)
  • Known to be currently pregnant (self-disclosed)

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: Basic Science
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Watermelon Condition
This group will maintain a normal diet supplemented with 2.5 cups (~375 grams, 115 kcals, 0.5g fat, 1.5g fiber, 17,225mcg lycopene, 30.75mg vitamin C) of fresh watermelon daily for six weeks
Other: Watermelon
2.5 cups of whole fresh watermelon (~375 grams, 115 kcals, 0.5g fat, 1.5g fiber, 17,225mcg lycopene, 30.75mg vitamin C) of fresh watermelon daily for six weeks
Other Names:
  • Whole Watermelon
  • Diced Watermelon
Active Comparator: Control Condition
This group will maintain a normal diet supplemented with an isocaloric control snack (Belvita breakfast sandwich; 115 kcals, 1.5g fiber, 4.5g fat, 0mg lycopene, 0mg vitamin C) as well as 12 ounces of water
Other: Belvita Breakfast Sandwich + 12 oz Water
Belvita breakfast sandwich; 115 kcals, 1.5g fiber, 4.5g fat, 0mg lycopene, 0mg vitamin C) as well as 12 ounces of water
Other Names:
  • Isocaloric Snack
  • Breakfast Sandwich
  • Control Snack

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Gut Microbiome Diversity
Time Frame: Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Collected fecal samples will be used to determine microbiome profiles, including diversity and composition of bacteria.
Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Change in Oral Microbiome Diversity
Time Frame: Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Oral swab samples are collected to determine oral diversity and composition of bacteria in the mouth before and after intervention.
Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Gut Transit Time
Time Frame: Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Evaluate changes in gut transit time after watermelon or control snack consumption from baseline to final analysis, using a blue-dye capsule.
Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Change in Arterial Stiffness
Time Frame: Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Evaluate the effects of watermelon on arterial stiffness, determined by measuring Pulse Wave Analysis (PWA) and Pulse Wave Velocity (PWV). These are captured by the SphygmoCor XCEL System through the descending aorta to the femoral artery. The aortic pulse wave velocity is detected from carotid and femoral arterial pulses measured non-invasively and simultaneously
Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Change in Endothelial Function
Time Frame: Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Evaluate the effects of watermelon on macrovascular endothelial function, which will be evaluated using the flow-mediated dilation (FMD) technique using a Finapres device, which measures the arterial dilation response following acute occlusion of the brachial artery.
Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Change in Ambulatory Blood Pressure
Time Frame: Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Evaluate the effect of watermelon on ambulatory blood pressure (systolic and diastolic), determined using a 12-hour ambulatory blood pressure monitor (TM-2440). The 12-hour ambulatory blood pressure monitor will collect blood pressure readings every 20 minutes during waking hours only.
Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Change in Waist and Hip Circumference
Time Frame: Screening, Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Evaluate changes in waist and hip circumference (centimeters), as well as waist-hip ratio at each study visit before, after and during watermelon consumption.
Screening, Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Change in Body Composition
Time Frame: Screening, Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Evaluate changes in body composition, including lean mass (kg), fat mass kg), and total body water (kg). This is assessed using a bioimpedance spectroscopy device (ImpediMed SBF7) at each study visit before, after and during watermelon consumption.
Screening, Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Change in Habitual Dietary Intake
Time Frame: Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Assess changes in habitual dietary intake via 3-day food logs, analyzed using nutrient analysis software.
Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Change in Biomarkers of Inflammation
Time Frame: Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Relevant biomarkers are to be collected via venous blood samples to determine changes in inflammation, including but not limited to C-reactive protein (CRP), IL-1 (Interleukin-1), IL-1 beta, IL-6, IL-10, IL-17, IL-23, Tumor Necrosis Factor Alpha (TNF-a), Interferon-gamma (IFN-Y). All will be expressed in units of pg/mL.
Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Change in Biomarkers of Appetite
Time Frame: Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Relevant biomarkers are to be collected via venous blood samples to determine changes in appetite including Insulin, Glucagon, glucagon-like peptide 1 (GLP-1), Adiponectin, Leptin, Ghrelin, and Peptide YY. All will be expressed in units of pg/mL.
Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Change in Biomarkers of Intestinal Barrier Function
Time Frame: Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Relevant biomarkers are to be collected via venous blood samples to determine changes in intestinal barrier function including LPS (lipopolysaccharides), LBP (lipopolysaccharide binding protein), CD14, Secretory IgA. All will be expressed in units of pg/mL.
Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Change in Biomarkers of Cardiometabolic Health
Time Frame: Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Relevant biomarkers are to be collected via venous blood samples to determine changes in cardiometabolic health including HDL, LDL, total cholesterol, and triglycerides. All will be expressed in units of mg/dL.
Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Change in Recent Dietary Intake
Time Frame: Screening, Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Assess changes in dietary intake via 24 hr recalls, analyzed using nutrient analysis software.
Screening, Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Change in Body Weight
Time Frame: Screening, Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Evaluate changes in body weight (kg) at each study visit before, after and during watermelon consumption.
Screening, Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Change in Body Mass Index
Time Frame: Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).
Evaluate changes in Body Mass Index (kg/m2) before, during and after consumption of watermelon.
Baseline (day 0), Visit 2 (week 6), Visit 3 (week 10), Visit 4 (week 16).

Collaborators and Investigators

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

Sponsor

Florida State University

Investigators

  • Principal Investigator: Ravinder Nagpal, PhD, 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.

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)

October 13, 2024

Primary Completion (Estimated)

December 1, 2026

Study Completion (Estimated)

December 1, 2026

Study Registration Dates

First Submitted

September 3, 2024

First Submitted That Met QC Criteria

September 4, 2024

First Posted (Actual)

September 19, 2024

Study Record Updates

Last Update Posted (Actual)

April 9, 2026

Last Update Submitted That Met QC Criteria

April 8, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • STUDY00005203

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Deidentified IPD will not be retain past three years, at the time of this submission the researchers does not plan to make IPD available

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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