Effects of a Standardized Freeze-dried Grape Powder on High Density Lipoprotein (HDL) Function in Metabolic Syndrome
Condition: Metabolic Syndrome X
MeSH terms: Metabolic Syndrome; Syndrome
Study type: Interventional

Summary: 
      The purpose of this study is to evaluate the effects of both chronic and acute grape
      ingestion in a population of men and women at higher risk for both type 2 diabetes and
      cardiovascular disease (metabolic syndrome).
    

Detailed description: 
      This study will involve a 2-week "run-in" period and two 4-week "intervention" phases
      separated by a 3 week "washout" non-intervention phase (for a total of 13 weeks). At the
      start of each 4-week intervention period, subjects will be asked to participate in a
      "postprandial challenge" test. Subjects will be asked to first follow a 2-week run-in control
      period consuming habitual diets but refraining from consuming polyphenol-rich
      foods/beverages, including tea, berries, grapes, juices, and wine. Subjects will then be
      asked to consume 60 g of grape powder or placebo in random order, each for a 4-week
      intervention period, separated by a 3-week washout period. Subjects will be asked to prepare
      powder by mixing with water at breakfast (30 g) and dinner (30 g) and consume immediately
      after mixing (or within 30 minutes). During each 4-week intervention period, subjects will be
      asked to refrain from consuming polyphenol-rich foods/beverages. During the washout period
      subjects will not be asked to consume the powder, but should abstain from consuming
      polyphenol-rich foods/beverages. The grape powder is made from a composite of fresh red,
      green and black California grapes, based on actual consumption patterns of consumers. It is a
      mix of seeded and seedless varieties that have been frozen, ground with food-quality dry ice,
      freeze-dried, and re-ground. Subjects will also be asked to maintain normal diet and exercise
      habits throughout the study, with the exception being the consumption of polyphenol-rich
      foods/beverages. Subjects will be asked to complete a 5-day dietary record (including 1
      weekend day) and a 7-day physical activity diary at the baseline and end of each intervention
      period. Subjects will come to the University of Connecticut Nutrition Department once every
      other week (biweekly) to pick up the powder (in packets), which needs to be kept frozen until
      consumption.

      For the postprandial challenge tests, subjects will be asked to fast overnight (12 hours) and
      then will be given a coconut oil-based lactose-free milkshake (1 g fat/kg body weight),
      containing 60 g of either placebo or grape powder. Subjects will be asked to spend the test
      day in the laboratory in a rested state and, with the exception of water, will not be
      permitted to consume any additional food or beverages during the 6 hours after consuming the
      milkshake. Subjects will be asked to abstain from alcohol and strenuous physical activity
      24-hours prior to the postprandial test. To standardize short-term fat intake, subjects will
      be given recipes and instructed to consume a low-fat evening meal (< 10 g fat) the night
      prior to postprandial tests. Subjects will also be asked to complete a 1-day food record for
      the day prior to the postprandial tests.
    

Intervention name(s): Freeze-dried Whole Grape Powder; Grape Powder Placebo
Intervention type(s): Other; Other
Intervention description(s): 60 g of whole grape powder for 4 weeks; 60 g of grape powder placebo for 4 weeks
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Basic Science
Keywords: Metabolic Syndrome; Grape; HDL; Lipoproteins