Vitis Intervention Trial in Substrate Metabolism

Sponsor
University of Alabama at Birmingham
Study ID
NCT07800988
Status
Not Yet Recruiting

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Conditions

  • Healthy Adult
  • Obesity & Overweight

Eligibility Criteria

Sex
ALL
Age
25 Years - 60 Years
Healthy Volunteers
Accepted

Interventions

  • 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
    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.

Study Details

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).

Key Dates

First listed
Sep 2, 2026
Start date
Sep 30, 2026
Status verified
Aug 2026
Primary completion
Jul 31, 2027
Completion
Sep 30, 2027

Study Design

Enrollment
20 participants (estimated)
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
PREVENTION

Arms

  • Active Comparator: Grape Powder
    Grape Powder Participants receive freeze-dried whole grape powder during a 40-hour calorimeter stay. Freeze-Dried Whole Grape Powder - 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 Comparator: Placebo
    Participants receive matched placebo during a 40-hour calorimeter stay. 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.

Primary Outcome Measure

Postprandial Respiratory Exchange Ratio (RER) [ 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. ]

Central Contacts

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