Effects of Short-term Diet on HDL Composition and Function
Condition: Diet Modification; HDL; Inflammation
MeSH terms: Inflammation
Study type: Interventional

Summary: 
      The primary objective of this study is to generate preliminary data on the effects of a
      short-term diet of either fast food or Mediterranean type diet on HDL and microbiota
      composition and function in healthy subjects, which includes both normal weight and
      overweight/obese subjects.
    

Detailed description: 
      Subjects will be recruited through word-of-mouth, flyers, newspaper advertisements, and
      postings on the UC Davis Nutrition Department website. Interested individuals who respond to
      notices will undergo a telephone screen to assess eligibility. A copy of the flyer, the
      Nutrition Department website notice, newspaper advertisement, and phone screen are attached
      with this submission. The subject population may reflect the ethnic and cultural diversity of
      the region.

      Screening and Consent Prospective subjects who pass the initial phone screening interview
      (i.e. meet inclusion/exclusion criteria) will be admitted into the study and scheduled for a
      consent visit. At the consent visit, after singing the consent form and agreeing to
      participate, participants' weight, height, and blood pressure will be measured to ensure that
      they meet inclusion criteria, and if their measurements agree with their reported values they
      will be admitted into the study and scheduled for their baseline visit. At the consent visit,
      subjects will also be instructed on how to complete a 3-day food record and will be asked to
      complete and return it before the baseline visit. Participants will also be given a stool
      collection kit during the consent visit to collect stool samples within 24 hours before their
      first scheduled visit. Women who consent to participate will be scheduled to complete the
      study within the luteal phase and menses of the menstrual cycle to avoid confounding
      alterations in lipoproteins. If women participants are not able to remember the first day of
      their last menstrual cycle, they will be instructed to note the start of their next menstrual
      cycle and will then be scheduled accordingly thereafter. Subjects will be randomized to begin
      either on the fast food arm or the Med arm. Each cohort of 4 participants will have 2
      individuals who begin on the Med diet arm, and 2 individuals who begin on the fast food diet
      arm, and each participant will be randomized into one of these two blocks and be assigned a
      study ID number.

      Baseline Visit A At the scheduled baseline visit subjects will report to the Ragle Human
      Nutrition Research Center located on the UC Davis campus (1283 Academic Surge, University of
      California, Davis, in Davis CA 95616) for a 12-hour fasting blood draw and anthropometric
      measurements. They will be asked to bring their stool sample to this visit. Each participant
      will also be asked to complete a health history questionnaire, a physical activity
      questionnaire, and a Food Frequency Questionnaire (FFQ). The duration of the baseline study
      visit will be approximately 1 hour.

      Study Arm 1: (4 days) Following the baseline blood draw, subjects randomized to begin on the
      fast food arm will consume a fast food diet for 4 days, Subjects randomized to begin on the
      Med diet arm will consume foods provided to them and follow basic food preparation
      instructions. At the end of each 4-day-long diet phase, subjects will report to the Ragle
      Human Nutrition Research Center again for their first follow-up study visit (Study Visit 2).
      Participants will be required to collect another stool sample to bring with them to their
      visit and will complete a hunger and satiety questionnaire at either the lunch or dinner meal
      each day on each diet arm.

      During the Med diet arm, participants will pick up their meals and instructions from the
      study team. During the fast food diet arm, participants will be given gift cards and meal
      plans to follow for the on-campus fast food restaurants and will purchase meals at the fast
      food restaurants on their own. For both dietary interventions, participants will follow the
      appropriate meal plan, attached with this submission. They will also be instructed to
      maintain their physical activity level during the study period. Subjects will be contacted
      once during each dietary period by e-mail or phone and will be asked about their general
      wellbeing, and to remind them to collect a stool sample for the next visit. To monitor
      compliance, participants will fill out a compliance survey as well as bring in any leftover
      food they do not consume. The leftover foods plus packaging will be weighed, and the weight
      of packaging alone subtracted in order to obtain an accurate measurement of how much
      participants actually consumed.

      Study Visit B This study visit will also be approximately 1 hour in duration, and will also
      include a fasting blood draw, anthropometric measurements, and the same questionnaires as the
      baseline study visit except they will not complete an FFQ. Participants will receive the
      first installment of their study compensation at this time.

      Study Washout Period: (4 days) Following Study Visit B, subjects will enter a 4-day washout
      period, in which they will return to their normal diets. Subjects will be required to
      complete a 3-day food record during this time. At the end of the 4-day washout period,
      subjects will return to the Ragle facility for the second follow-up Visit (Study Visit C).
      Participants will be required to collect another stool sample to bring with them to their
      visit.

      Study Visit C This study visit will also be approximately 1 hour in duration, and will also
      include a fasting blood draw, anthropometric measurements, and the same questionnaires as
      study visit B. Participants will receive the second installment of their study compensation
      at this time.

      Study Arm 2: (4 days) At this time, participants who completed the mMed diet arm will now
      begin the fast food diet arm, and those who completed the fast food diet arm will now enter
      the mMed diet arm. All participants will be asked to complete a hunger and satiety
      questionnaire during this time (4 days). At the end of the 4-day period subjects will return
      for the third follow-up study visit (Study Visit D). Participants will be required to collect
      a final stool sample to bring with them to their visit.

      Study Visit D This study visit will also be approximately 1 hour in duration, and will also
      include a fasting blood draw, anthropometric measurements, and the same questionnaires as
      study visits B and C. Subjects will receive the rest of their compensation at this time.
    

Intervention name(s): Mediterranean Diet; Fast food diet
Intervention type(s): Other; Other
Intervention description(s): four days of participant-scaled isocaloric Mediterranean meals; four days of participant-scaled isocaloric fast food meals
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: Randomized two-way crossover design
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: Mediterranean diet; HDL; Fast food; Gut microbiota; Inflammation