Recruiting

Grape Powder

Sponsor:

UCLA

Code:

NCT06544954

Conditions

Arterial Stiffness

Blood Pressure

Dysbiosis

Inflammation

Permeability; Increased

Eligibility Criteria

Sex: All

Age: 45 - 70

Healthy Volunteers: Accepted

Interventions

Freeze-dried grape powder

Placebo powder

Study Details

Brief summary:

The goal of this clinical trial is to assess the impact of table grape consumption on gut microbiome, intestinal permeability, systemic inflammation, and vascular function in healthy overweight men and women aged 45-70 years. The main questions it aims to answer are:

  • Does daily grape intake alter intestinal microbiome composition and intestinal permeability?
  • Are changes in gut microbiota and intestinal permeability correlated with changes in cardiometabolic risk factors (inflammation, vascular function, lipid profiles)?
  • Does response to grape intake on gut microbiota, intestinal permeability, cardiometabolic and inflammatory markers differ between men and women?
  • Are metabolic pathways modified by grape consumption able to explain the link between gut health and cardiometabolic factors?

Researchers will compare freeze-dried grape powder to placebo powder to see if grape powder improves cardiometabolic risk factors.

Participants will

  • Consume the powder dissolved in water twice daily for 3 weeks
  • Follow their usual diet, modified to limit polyphenol-rich foods
  • Visit the clinic at the beginning and end of the intervention for vascular measurements and blood sample collection
  • Complete a 3-day 24-hour dietary recall and collect stool sample before each visit

Conditions

Arterial Stiffness

Blood Pressure

Dysbiosis

Inflammation

Permeability; Increased

Study ID

NCT06544954

Start date

May 7, 2025

Status verified date

Apr, 2026

Completion date

Jan, 2027

Anticipated

Primary completion date

Nov, 2026

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 45 - 70

Healthy Volunteers: Accepted

Inclusion Criteria:

  • post-menopausal women (cessation of menstruation for minimum two years)
  • overweight and obese (BMI between 25-35 kg/m2)
  • stable treatment for type 2 diabetes or metabolic syndrome
  • ability to understand the intervention concept and written consent to participate
  • willingness to accept randomization, undergo testing and intervention procedures, and deliver stool and blood samples

Exclusion Criteria:

  • menopausal hormone replacement therapy started within less than 6 months
  • antibiotics, prebiotics within last 3 months
  • antidiabetic treatment involving insulin (for type 1 diabetes)
  • vegetarian/vegan and not able to follow modified diet
  • any serious medical condition including but not limited to coronary artery disease, uncontrolled hypertension, stroke, congestive heart failure, insulin-dependent diabetes, liver disease, active cancer and anemia
  • psychiatric disease that interferes with the understanding and implementation of the intervention
  • history of eating disorders such as bulimia nervosa, anorexia nervosa, severe binge eating disorder in the last 5 years
  • history of substance abuse or alcohol abuse
  • involvement in a weight loss intervention program (including anti-obesity medication) within last 3 months or have had bariatric surgery
  • current smokers (within last 180 days)
  • use of dietary supplements containing polyphenols in the past 1 month
  • strenuous exercise greater than 10 hours per week

Study Design

Enrollment

40 participants

Anticipated

Allocation

Randomized

Intervention Model

Crossover

Primary purpose

Prevention

Interventions and Outcome Measures

Arms

experimental: Grape, Then Placebo

Participants consume 48 grams of freeze-dried grape powder (dissolved into water) twice daily for 3 weeks. After a washout period of at least 3 weeks, participants then consume 48 grams of placebo powder matching grape powder (dissolved into water) twice daily for 3 weeks.

experimental: Placebo, Then Grape

Participants consume 48 grams of placebo powder matching grape powder (dissolved into water) twice daily for 3 weeks. After a washout period of at least 3 weeks, participants then consume 48 grams of freeze-dried grape powder (dissolved into water) twice daily for 3 weeks.

Interventions

Freeze-dried grape powder

48 grams powder

Placebo powder

48 grams powder

Primary outcome measure

  • Arterial stiffness Change from Baseline [ Time Frame: Baseline (Visit 1), Week 3 (Visit 2), Week 9 (Visit 4) ]
  • Blood pressure Change from Baseline [ Time Frame: Baseline (Visit 1), Week 3 (Visit 2), Week 9 (Visit 4) ]
  • Gut microbiome composition Change from Baseline [ Time Frame: Baseline (Visit 1), Week 3 (Visit 2), Week 9 (Visit 4) ]
  • Gut permeability markers Change from Baseline [ Time Frame: Baseline (Visit 1), Week 3 (Visit 2), Week 9 (Visit 4) ]
  • Systemic inflammatory markers Change from Baseline [ Time Frame: Baseline (Visit 1), Week 3 (Visit 2), Week 9 (Visit 4) ]
  • Lipid and metabolic profiles Change from Baseline [ Time Frame: Baseline (Visit 1), Week 3 (Visit 2), Week 9 (Visit 4) ]

Central Contacts and Locations

Central contacts

Dragan Milenkovic, PhD

(530) 219-5872dmilenkovic@ucdavis.edu

Shannon H Trinh, MS, RD

(408) 802-9356shtrinh@ucdavis.edu

Locations

Ragle Human Nutrition Center

Recruiting

Davis, California, United States, 95616

Contacts

Jody Randolph

530-752-7620jmrandolph@ucdavis.edu

Principal Investigator:

Dragan Milenkovic, PhD

More Information

Sponsor

University of California, Davis

Last update posted

Apr 13, 2026

Last verified

Apr, 2026

Keywords

  • gut microbiome
  • nutrition
  • cardiometabolic health

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-10. This information was provided to ClinicalTrials.gov by University of California, Davis on 2026-04-13.