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Prebiotic Effects of California Grapes on Gut Health and Cardiometabolic Health in Overweight Men and Women

University of California, Davis · with California Table Grape Commission · NCT06544954

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Opens the official ClinicalTrials.gov record, with the study team’s contacts. Bored Studies doesn’t enroll anyone.

Key facts

Compensation
Not posted. Ask the study team before screening.
Who can join
Ages 45–70 · All sexes
Healthy volunteers
Accepted
Study type
Interventional · Not applicable
Target enrollment
40
US sites recruiting
1
Study start
May 7, 2025
Record last updated
April 13, 2026

Status re-checked against ClinicalTrials.gov within the last 12 hours.

What the study is about

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

Being studied: Freeze-dried grape powder; Placebo powder

Conditions: Arterial Stiffness; Blood Pressure; Dysbiosis; Inflammation; Permeability; Increased

Eligibility criteria

Copied from the official record. The study team makes the final decision at screening.

Show full criteria

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

Recruiting US locations

  • Ragle Human Nutrition Center

    Davis, CA 95616

    Site contact: Jody Randolph · 530-752-7620 · jmrandolph@ucdavis.edu

Study contacts (from the official record)

  • Dragan Milenkovic, PhD · (530) 219-5872 · dmilenkovic@ucdavis.edu
  • Shannon H Trinh, MS, RD · (408) 802-9356 · shtrinh@ucdavis.edu
All weight loss studies in California →
Prebiotic Effects of California Grapes on Gut Health and… (NCT06544954) | Bored Studies