Effect of Watermelon on Cardiometabolic Health

NCT ID: NCT07006636

Last Updated: 2025-12-15

Basic Information

• Recruitment Status: NOT_YET_RECRUITING
• Clinical Phase: NA
• Total Enrollment: 22 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2026-01-01
• Study Completion Date: 2027-07-01

Brief Summary

The purpose of this study is to determine whether consumption of 355 ml of watermelon juice will:

1. improve cardiovascular and overall metabolic health markers like blood pressure, heart rate, stiffness/flexibility of arteries (blood vessels), blood sugar, cholesterol), and gut hormones

2. contribute to the body's ability to protect itself from the potential cell damage caused by harmful chemical compounds (produced when skin is exposed to ultraviolet (UV) B light, for example). This will be evaluated by measuring how resistant skin is to the damage from UVB light exposure, as well as several markers of bodily stress blood and urine.

This will be determined immediately after consuming the juice (to evaluate the effects the juice has on health right away), as well as after 4 weeks of daily juice consumption (to evaluate the effects the juice has on health when consumed consistently over time).

Detailed Description

Both hypertension and oxidative stress are among the major risk factors for cardiovascular disease (CVD). While CVD is a multifactorial disease, it has been established that diet plays an integral role in its pathogenesis. In fact, it has been previously demonstrated that almond and pomegranate consumption may be able to strengthen the body's antioxidant defense mechanisms and aid in improving several cardiometabolic health biomarkers. Watermelon, being rich in fiber, vitamins, minerals, and bioactive compounds (e.g., L-citrulline, lycopene, beta-carotene) may also have similar health effects. Notably, studies involving both mice and humans have demonstrated the potential of watermelon consumption to prevent CVD by lowering blood pressure and low-density lipoprotein cholesterol (LDL-C).

Emerging evidence suggests that postprandial biomarker levels may serve as better and earlier predictors of CVD development than their fasting levels. While watermelon is often consumed with or after a meal, no studies have evaluated the effect of watermelon on postprandial biomarker responses after a meal challenge. In addition, despite the high bioactive content of watermelon, its effects on whole-body antioxidant capacity have not been explored yet.

Therefore, in the present study it is proposed to evaluate the acute (postprandial) and chronic (4 weeks of daily consumption) effects of 355 ml of watermelon juice (WMJ) on: 1) cardiometabolic risk factors including blood pressure, heart rate, pulse wave velocity (PWV), blood glucose and lipids/lipoproteins, nitric oxide (NO), insulin/C-peptide, and GLP-1; and 2) whole-body antioxidant capacity by evaluating skin resistance to UV irritation, as well as blood and urine malondialdehyde (MDA) levels. A two-phase intervention study (2-week standardization phase and a 4-week intervention phase) involving 20 generally healthy non-vegetarian/vegan postmenopausal women with slightly elevated blood pressure, overweight/obese BMI, and Fitzpatrick's skin types II-IV will be performed. Investigating the effects of WMJ consumption on cardiometabolic risk factors and skin antioxidant defense/systemic oxidative status will uncover valuable new insights into whether bioactive compounds in watermelon can affect cardiometabolic risk and contribute to the total body antioxidant capacity.

Conditions

Cardiometabolic Health Indicators; Whole-body Antioxidant Capacity

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: CROSSOVER
• Primary Study Purpose: PREVENTION
• Blinding Strategy: TRIPLE

Study Groups

Watermelon Juice + liquid meal test at baseline

Acute (postprandial) as well as chronic (4 weeks) effects of WMJ consumption will be evaluated. To evaluate acute effects participants will consume a liquid meal test together with WMJ at the beginning of the intervention phase. In addition, the same liquid meal test will be consumed with only WMJ at the end of the intervention phase to assess whether drinking the juice for 4 weeks prior had any effects on postprandial responses.

Group Type: EXPERIMENTAL

Watermelon Juice + liquid meal test at baseline

Intervention Type: OTHER

WMJ will be purchased from a commercially available brand. The liquid meal test will be in the form of the Boost nutritional drink (8 fl.oz., vanilla flavor), which is commercially available.

Sweetened placebo beverage + liquid meal test at baseline

Participants will consume placebo beverage + liquid meal test at baseline. They will then consume watermelon juice daily for 4 weeks. Watermelon juice + liquid meal test will be consumed at endpoint.

Group Type: PLACEBO_COMPARATOR

Sweetened placebo beverage +liquid meal test at baseline

Intervention Type: OTHER

The placebo beverage made of water and sugar will match the sugar content provided in 355 ml of WMJ (approximately 10-20 g). The liquid meal test will be in the form of the Boost nutritional drink (8 fl.oz., vanilla flavor), which is commercially available.

Interventions

Watermelon Juice + liquid meal test at baseline

WMJ will be purchased from a commercially available brand. The liquid meal test will be in the form of the Boost nutritional drink (8 fl.oz., vanilla flavor), which is commercially available.

Intervention Type: OTHER

Sweetened placebo beverage +liquid meal test at baseline

The placebo beverage made of water and sugar will match the sugar content provided in 355 ml of WMJ (approximately 10-20 g). The liquid meal test will be in the form of the Boost nutritional drink (8 fl.oz., vanilla flavor), which is commercially available.

Intervention Type: OTHER

Eligibility Criteria

Inclusion Criteria

• Female
• Generally healthy
• Postmenopausal
• BMI 25-40 kg/m2
• Systolic blood pressure 120-139 mmHg and/or diastolic 80-89 mmHg
• Fitzpatrick Skin type II-IV
• Consume a typical Western diet (low in polyphenol/lycopene-rich foods and fiber)
• Willing to maintain habitual dietary and exercise patterns for the study duration
• Willing to maintain normal skin care products and pattern for the duration of the study
• Willing to come to Baseline Visit B and Week 4 study visits without any makeup and skin products on
• Subjects must read and sign the Institutional Review Board-approved written informed consent prior to the initiation of any study specific procedures or enrollment. A subject will be excluded for any condition that might compromise the ability to give truly informed consent.

Exclusion Criteria

• Non-English speaker
• Vegetarian/vegan
• Known watermelon allergy
• Skin-related prescription medication, supplements, or non-prescription cosmeceutical agents
• Initiation of topical or oral prescription steroids and/or anti-inflammatory medications within 30 days prior to study enrollment
• Excessive exposure to either natural or artificial sunlight. Exposure to sunlight will be evaluated using Fitzpatrick Skin Type test score. Individuals receiving scores higher than the upper cutoff of the proposed range for the specific skin type will be excluded
• Screening laboratory values outside of the normal range that is considered clinically significant for study participation by the investigator
• Documented chronic disease, including diabetes, renal or liver diseases, metabolic syndrome, active cancer, MI or stroke, history of gastric bypass or GI disease (e.g., Crohn's disease, IBD, diverticulosis, diverticulitis, etc.)
• Taking medications or supplements known to affect metabolism or gut microbiota composition (antibiotics within the past 3 months, probiotics, fiber, etc.), unless willing to stop for the study duration
• Taking exogenous hormones (e.g., hormone replacement therapy)
• Recent weight fluctuations (>10% in the last 6 months)
• Smoker or living with a smoker
• Use of >20 g of alcohol per day
• Unable or unwilling to comply with the study protocol (including unwillingness to avoid watermelon and other lycopene-rich foods for the whole duration of the study)
• Unable to provide consent

• Eligible Sex: FEMALE
• Accepts Healthy Volunteers: Yes

Sponsors

National Watermelon Promotion Board

OTHER

Sponsor Role: collaborator

University of California, Los Angeles

OTHER

Sponsor Role: lead

Responsible Party

Zhaoping Li

Principal Investigator

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Zhaoping Li, MD, PhD

Role: PRINCIPAL_INVESTIGATOR

University of California, Los Angeles

Locations

UCLA Center for Human Nutrition

Los Angeles, California, United States

Countries

United States

Central Contacts

Tatiana Diacova, PhD, MS, RDN

Role: CONTACT

tdiacova@mednet.ucla.edu

3102068292

Facility Contacts

Tatiana Diacova, PhD, MS, RD

Role: primary

tdiacova@mednet.ucla.edu

310-206-8292

Other Identifiers

IRB-25-1126

Identifier Type: -

Identifier Source: org_study_id