Effects of Prolonged Fasting on Microbiome and HDL
Condition: Fasting
Study type: Interventional

Summary: 
      Participants will undergo one day of habitual eating followed by 36 hours of water only
      fasting and final day of habitual eating of the exact same diet consumed on the first eating
      day. Blood draws will be performed on Day 1 in a 10-12 hr fasted state and 2 hour
      postprandial state and again on Day 3 in a 36hr fasted state and a 2 hour post prandial
      state. Microbiome samples and blood glucose data will be collected throughout the course of
      the study.
    

Detailed description: 
      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, subjects who decide to participate will be given a series of
      questionnaires including a health history questionnaire, physical activity questionnaire, and
      will be asked to complete a 3-day diet record, to be completed before the baseline visit at
      the beginning of the study. Women who consent to participate will be scheduled to complete
      the study within the follicular phase and menses of the menstrual cycle to avoid confounding
      alterations in lipoproteins.

      Study Visit1 (Baseline fasted):

      On Day 1 of the study protocolstudy participants 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 overnight fasting blood draw and
      anthropometric measurements at approximately 8AM. Any participants that are found to have
      fasting glucose above or below 70-100mg/dL will be removed from the study. Study participants
      will be given a Precision Xtra Blood Ketone Testing Kit to collect blood ketone data during
      the fasting period of the study protocol, a set of stool collection kits to collect stool
      samples throughout the rest of the study protocoland fitted with a GoBe activity monitor to
      track physical activity throughout the rest of the study protocol. Proper use, care, and
      storage of the Precision Xtra systems, stool collection kits, and GoBe monitors will be
      explained in detail to study participants during the baseline visit. Study participants will
      be given a 24-hr food diary to record their food and beverage intake throughout the rest of
      the day or may be asked to track their diet using GB 360.

      Study Visit 2 (Baseline postprandial):

      After the baseline visit on Day 1 of the study protocol, study participants will go about
      their normal routines and eat their habitual diet ad libitum while recording their dietary
      intake throughout the day. This food record will be used in order for the study participants
      to mimic their food intake on Day 1 during the eating period on Day 3 of the study protocol.
      Study participants will eat their last meal of the day at approximately 6PM. Post-prandial
      blood samples will be collected at 2 hours after the ingestion of this last meal and
      immediately processed to yield patient plasma and isolated PBMCs to be stored for future
      analysis. These post-prandial samples will constitute the baseline "Fed" state of each
      participant. Study participants will also perform their first bloodprick for ketone
      measurement using the Precision Xtra Monitor under instruction and supervision by study
      personnel.

      Fasting:

      After ingestion of their final meal, participants will undergo a full 36 hours of fasting
      comprising Day 2 and the beginning of Day 3 of the trial without otherwise modifying their
      typical routine, including drinking coffee or tea (but with no creamers or sweeteners of any
      kind), if this is part of their normal routine. The time of the ingestion of the standardized
      meal will be used as the start point (0hr) for the continuous 36 hours of fasting. 36 hrs of
      fasting has been shown to be well tolerated in human subjects and was chosen for this trial
      as it represents the approximate amount of time that fasting would be experienced during a
      single cycle of an alternate day fasting regimen. Therefore, results from this study could be
      generalized to plan for future studies of alternate day fasting. Subjects will be encouraged
      to report any feelings of dizziness, headaches, nausea, or severe hunger that they may
      experience and, based on the severity of their conditions, will be advised whether or not to
      continue with the trial. Subjects will be asked to take small blood pricks starting
      immediately after waking up on Day 2 and then every 3 conscious hours thereafter using
      thePrecision Xtra Blood Ketone Testing Kits in order to test blood ketone levels during the
      fasting period. Ketone levels obtained from the blood pricks will be recorded automatically
      by the Precision Xtra monitor.

      Study Visit 3 (Post 36h fasted):

      At 36 hours of fasting, roughly 8AM on Day 3, subjects will return to the Ragle Center,
      perform a final blood prick for ketone monitoring by the Precision Xtra and their blood
      samples will be collected and again immediately processed and stored for future analysis
      constituting the "Fasted" state for each participant.

      Study Visit 4 (Post 36h postprandial):

      After the blooddraw at Study Visit 3, study participants will be allowed free access to food
      throughout the rest of the day and asked to eat an identical diet to the dietary intake the
      participants recorded on Day 1 in their 24 hour food diary. Subjects will eat their last meal
      at approximately 6PM. Post-prandial blood samples will be collected at 2 hours after the
      ingestion of this last meal and immediately processed to yield patient plasma and isolated
      PBMCs to be stored for future analysis. These post-prandial samples will constitute the
      "Refed" state of each participant. After this final blood draw, the Precision Xtra system
      will be collected, the GoBe removed, and the activity and ketone data collected throughout
      the course of the study will be transferred to a secure computer for analysis. Fasting
      compliance will be determined as 1) increasing or steady ketone levels throughout the 36hr
      fasting period and 2) the absence of significant drops in blood ketone levels, which would
      indicate food intake and noncompliance.

      StoolCollection (Days 1-3):

      Study participants will use the provided stool collection kits to collect stool samples from
      each bowel movement throughout the entire course of the study. Stool samples will be obtained
      from study participants at the Ragle Center as soon as possible after initial collection by
      study participants, frozen, and stored at -80C.
    

Intervention name(s): Fasting
Intervention type(s): Other
Intervention description(s): Participants will undergo one day of habitual eating followed by 36 hours of water-only fasting and final day of habitual eating consuming the exact same diet consumed on the first eating day. Blood draws will be performed on Day 1 in a 10-12 hr fasted state and 2 hour postprandial state and again on Day 3 in a 36hr fasted state and a 2 hour post prandial state. Microbiome samples and blood glucose data will be collected throughout the course of the study.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: Microbiome; High Density Lipoprotein; Inflammation