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NCT Number: NCT06588218

Effect of Watermelon on Gut and Cardiometabolic Health

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?

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Key information

Conditions

Obesity and Overweight Body Weight Dysbiosis Nutrition Disorders Nutritional and Metabolic Diseases Obesity Overnutrition Overweight Pathologic Processes Pathological Conditions, Signs and Symptoms Signs and Symptoms

Age range

18 year–30 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Florida State University - Gut Biome Lab

Tallahassee, Florida, 32306, United States

Location status: Recruiting

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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)

Treatment and study plan

Watermelon

Other

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

Belvita Breakfast Sandwich + 12 oz Water

Other

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

Primary outcomes

  1. 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.

  2. 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.

Secondary outcomes

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

Interested in participating?

Recruiting

Interested in participating?

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Sponsors and collaborators

Lead sponsor

Florida State University

Other

Registry information

Official study title

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

Important dates

Study start
2024
Primary completion
2026
Study completion
2026
First posted
Sep 19, 2024
Registry last updated
Apr 9, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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