Health TrialsbyHealthPanel

Vitis Intervention Trial in Substrate Metabolism

ConditionsObesity & OverweightHealthy Adult
Trial statusNot yet recruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age25-60
SponsorUniversity of Alabama at Birmingham

About this trial

Obesity is associated with reduced metabolic flexibility (MetFlex), the capacity to shift between carbohydrate and lipid oxidation in response to nutrient availability. Grape polyphenols (resveratrol, catechins, quercetin, epicatechin) enhance fat oxidation and mitochondrial function in laboratory and animal studies, but whole grapes, rather than purified extracts, have not been tested for acute effects on MetFlex measured directly by whole-room calorimetry paired with mitochondrial function. This study integrates whole-room indirect calorimetry with high-resolution respirometry in peripheral blood mononuclear cells (PBMCs) to determine whether whole grape polyphenols shift the postprandial respiratory exchange ratio (RER) response to a high-fat meal and alter mitochondrial respiration, and whether responses differ by adiposity phenotype (lean vs. overweight/obesity).

Eligibility criteria

This trial accepts healthy volunteers

Qualifiers

Men and women aged 25-60 years

BMI 18-24.9 kg/m² (lean phenotype, n=10) or BMI 25-40 kg/m² (overweight/obesity phenotype, n=10)

Low habitual grape consumption

Weight stable (no change >5% in prior 6 months) and not actively attempting weight change

Disqualifiers

Current smoking; drug or alcohol abuse

Claustrophobia or psychiatric conditions that would make a 40-hour confined stay especially distressing or harmful

Weight instability, recent/active weight-loss attempts, or structured exercise initiation during the study

Hormone replacement therapy or medications known to affect metabolism

Trial design

Design model

Crossover

Treatments tested in this trial

  • Freeze-Dried Whole Grape Powder

    Dietary supplement

    72 g, reconstituted with water, administered once per calorimeter stay, 30 minutes before the standardized high-fat test meal. Other name: whole California table grape powder.

  • Placebo

    Other intervention

    Placebo Powder - 72 g matched placebo formulated to replicate the sugar, fiber, organic acid, and sensory characteristics of the grape powder without polyphenolic compounds; administered on the same schedule.

Treatment groups

20 Participants
are divided into 2 treatment groups
Group A: Grape PowderActive comparator 1 intervention
Group B: PlaceboPlacebo comparator 1 intervention

Trial outcomes

Primary outcomes

1

Postprandial Respiratory Exchange Ratio (RER)

Response to High-Fat Test Meal (ΔRER), compared between grape powder and placebo conditions

Time frame
Measured continuously by whole-room indirect calorimetry from the high-fat test meal (~18:30) through the postprandial blood draw (~21:30), Day 1 of each 40-hour calorimeter stay.

Secondary outcomes

1

Sleeping RER

Compared between grape powder and placebo conditions

Time frame
Overnight (~22:00-06:00; approximately 8 hours) Day 1 of each calorimeter stay
2

Postprandial PBMC mitochondrial respiration

fatty-acid-supported respiration

Time frame
Assessed from postprandial blood draw, 3 hours after test meal, Day 1 of each calorimeter stay
3

DXA-derived Fat Mass

fat mass (kilograms)

Time frame
Measured at screening
4

Resting Energy Expenditure

Measured by metabolic cart to determine weight stability and calorimeter stay calorie needs

Time frame
Measured at screening

Other outcomes

Locations

This trial has no locations.

Sponsors and contacts

Click on the lead sponsor to view all of their trials.

University of Alabama at Birmingham

Lead sponsor

California Table Grapes Commission

Collaborator

Source ClinicalTrials.gov

This trial is not recruiting at the moment. You can still explore other options: