Prebiotic Effects of California Grapes on Gut Health and Cardiometabolic Health in Overweight Men and Women
NCT Number: NCT06544954
Acronym: CALGRAM
Status: NOT_YET_RECRUITING
Study Type: INTERVENTIONAL
Phases: NA
Conditions: Arterial Stiffness|Blood Pressure|Dysbiosis|Inflammation|Permeability; Increased
Interventions: DIETARY_SUPPLEMENT: Freeze-dried grape powder|OTHER: Placebo powder
Sponsor: University of California, Davis
Collaborators: California Table Grape Commission
Sex: ALL
Age: ADULT, OLDER_ADULT
Enrollment: 40
Study Design: Allocation: RANDOMIZED|Intervention Model: CROSSOVER|Masking: QUADRUPLE (PARTICIPANT, CARE_PROVIDER, INVESTIGATOR, OUTCOMES_ASSESSOR)|Primary Purpose: PREVENTION
Start Date: 2024-09
Completion Date: 2026-06
Locations: Ragle Human Nutrition Center, Davis, California, 95616, United States

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 4 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 dietary recall and collect stool sample before each visit

Primary Outcome Measures: Arterial stiffness Change from Baseline, Pulse Wave Velocity (PWV) from carotid to femoral artery after 5 minutes rest; PWV is an established index of aortic stiffness using a validated non-invasive device that allows online pulse wave recording and automatic PWV calculation, Baseline (Visit 1), Week 4 (Visit 2), Week 12 (Visit 4)|Blood pressure Change from Baseline, Average of latter 2 of 3 total measures (5 minutes apart) after 15 minutes of rest in a quiet room; automated sphygmomanometer will be used with participants in the seated position, Baseline (Visit 1), Week 4 (Visit 2), Week 12 (Visit 4)|Gut microbiome composition Change from Baseline, 16S rRNA sequencing of stool samples collected by participants from home in fecal collection tubes filled with DNA/RNA shield, Baseline (Visit 1), Week 4 (Visit 2), Week 12 (Visit 4)|Gut permeability markers Change from Baseline, ELISA (zonulin, LPS, LBP, sCD14, DAO) to assay fasted blood samples collected when participants visit the clinic, Baseline (Visit 1), Week 4 (Visit 2), Week 12 (Visit 4)|Systemic inflammatory markers Change from Baseline, Luminex - Th17 inflammatory cytokines of fasted blood samples collected when participants visit the clinic, Baseline (Visit 1), Week 4 (Visit 2), Week 12 (Visit 4)|Lipid and metabolic profiles Change from Baseline, Lipid panel, comprehensive metabolic panel of fasted blood samples collected when participants visit the clinic, Baseline (Visit 1), Week 4 (Visit 2), Week 12 (Visit 4)
Secondary Outcome Measures: Gut permeability marker Change from Baseline, bacterial DNA presence in blood from fasted blood samples collected in tubes with DNA/RNA shield when participants visit the clinic, Baseline (Visit 1), Week 4 (Visit 2), Week 12 (Visit 4)|Metabolomics and Lipidomics Change from Baseline, Pathway Analysis using data available from analysis of blood samples collected when participants visit the clinic, Baseline (Visit 1), Week 4 (Visit 2), Week 12 (Visit 4)|Global gene expression Change from Baseline, Microarrays of blood samples collected when participants visit the clinic, Baseline (Visit 1), Week 4 (Visit 2), Week 12 (Visit 4)