Red Raspberry Polyphenols on Gut Microbiome
Condition: Healthy Subjects; Pre-diabetes
MeSH terms: Prediabetic State; Glucose Intolerance
Study type: Interventional

Summary: 
      The primary objective aims are to assess the effects of regular consumption of red
      raspberries (RRB) with and without fructooligosaccharide (FOS) on the composition of the gut
      microbiota after 4 week intake and in parallel characterize plasma and urine metabolite
      profiles examining qualitative and quantitative intervention associated changes.
    

Detailed description: 
      The study will be performed as a single-blinded, randomized, crossover manner. Thirty
      subjects (20 insulin resistant subjects and 10 healthy subjects) will be randomly assigned
      into one of two sequences: sequence A (n=15) will be RRB then RRB+FOS (which means subject
      will consume only RRB (125 g/day(d) (equivalent to 1 cup fresh RRB)) with breakfast for 4
      weeks, and then after a 4-week washout period, that subject will consume the RRB with FOS
      (125 g/d RRB and 8 g/d FOS) for 4 weeks); sequence B (n=15) will be RRB+FOS then RRB (which
      means subject will receive the RRB with FOS for 4 weeks, a 4-week washout, and then the RRB
      for another 4-week). At the beginning and end of each 4-week treatment, subjects will undergo
      a 6-h Study Day (4 study days in 12-week study duration) followed by a 1-h next morning
      follow-up visit.

      Subjects will be required to meet several inclusion and exclusion criteria, which will be
      assessed through online survey and on-site clinic assessments, including questionnaires,
      blood analysis and anthropometric measures. Eligible subjects will be invited to participate
      in the study. Each subject will be asked to come for 1 Screening Visit, 4 dinner pick-ups
      (the day before each Study Day), 4 Study Days and 6 Weekly Meetings.

      During the Screening Visit, subjects will read, sign and date a written Institutional Review
      Board approved Informed Consent Form prior to performing any study procedure. And then they
      will be assessed their qualification, instructed on the process for completing study
      questionnaires and counseled to restrict intake of colored plant foods rich in phytonutrients
      the 3 days prior to each Study Day. They will be asked to restrict alcohol intake,
      coffee/tea/ caffeinated beverage intake and moderate / vigorous physical activity and to
      drink plenty of water to maintain hydration in the 24 h prior to each Study Day. They will be
      instructed to come to the Clinical Nutrition Research Center (CNRC) the day before each Study
      Day to pick up their dinner meal and evening snack. Subjects will be asked to get at least 7
      hours sleep and to come to the CNRC after a 10-h overnight fasting on each Study Day.

      Each Study Day will require subjects to be in the clinic for ~7 h to complete all baseline
      and post challenge beverage testing procedures, including a 6 h study day and a 1 h next
      morning follow-up visit. Subjects will be evaluated for compliance with the protocol (diet,
      exercise, sleep, fasting), have their body weight and blood pressure measured, ingest a cup
      of red raspberry drink (250 g RRB (equivalent to 2 cups fresh RRB) and 64 g glucose) and
      their blood, urine and feces samples will be collected.
    

Intervention name(s): Raspberry and fructooligosaccharide; Raspberry
Intervention type(s): Dietary Supplement; Dietary Supplement
Intervention description(s): Red raspberries (1 cup equivalent) with fructooligosaccharide (8 g); Red raspberries (1 cup equivalent)
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Single (Participant)
Primary purpose: Other
Keywords: Pre-diabetes; red raspberry; fructooligosaccharide; metagenomics; polyphenol bioavailability; glycemic response; insulin response