Choline Nutritional Status: Development of a Biomarker Panel
Condition: Healthy
Study type: Interventional

Summary: 
      People who eat diets low in choline should deplete their choline (Cho) stores, and
      measurements of Cho pool size using isotope dilution should reflect this depletion.
      Investigators will identify a biomarker panel that correlates well with measured Cho pool
      size across the range of different degrees of depletion.The investigators propose that, as
      body stores of Cho diminish, cells and organs will reach the point when metabolism/function
      in the cell is altered, and that this will result in a progression of changes in biomarkers
      that reflect Cho status.
    

Detailed description: 
      Choline (Cho) is an essential nutrient and most Americans' diets do not achieve the
      recommended intake. Diets low in Cho are associated with liver and muscle disease and with
      suboptimal fetal development, while diets too high in choline may be associated with
      increased risk for heart disease. Cho is a required nutrient and in 1998, an Adequate Intake
      (AI) and a Tolerable Upper Limit (UL) for Cho was established In 2016, the US Food and Drug
      Administration (FDA) set a Recommended Daily Intake (RDI) for Cho based on the AIs as part of
      the new Nutrition Facts label for packaged foods (published in the Federal Register on May
      27, 2016; FDA-2012-N-1210-0875, Federal Register Number:2016-11867). The AI/RDI varies by age
      and gender, but is 550 mg/d in adolescent and adult men and 425 mg/d in adult women (more in
      pregnant and lactating women) and 400 mg/day for adolescent women.

      There is no validated biomarker for choline status (the availability of the various forms of
      Cho needed to sustain optimal cellular function). Measurement of plasma Cho concentrations is
      not adequate as plasma choline is homeostatically regulated. Based on extensive preliminary
      and published data this group identified a panel of potential biomarkers that could be used
      to assess Cho status, and now the investigators propose to validate this biomarker panel
      against measures of Cho pool size using isotope dilution. The largest stores of Cho are
      located in the liver, and mass resonance spectroscopy (MRS) of liver has been used in the
      past to assess Cho status in humans. This method is not practical for use as a biomarker in
      clinical or public health practice as it is expensive and the availability of the
      instrumentation is limited. However, the MRS can be utilized to confirm correlations between
      the biomarker panel and the isotope dilution method. Liver biopsy is risky and not practical,
      making measurement of hepatic Cho and Cho metabolites concentrations a poor choice for
      assessing Cho status.

      Perhaps there is a panel of biomarkers that together will more accurately and reliably
      reflect Cho status. By making measurements in people fed 3 different dietary amounts of Cho
      for two weeks at a time, and comparing the biomarker measures to body total Cho pool size
      assessed using isotope dilution (a proxy for the availability of the various forms of Cho),
      investigators will be able to identify the combination of biomarkers and algorithm for
      calculating a Cho status score that best predicts total Cho pool size, and therefore predicts
      choline nutritional status (the availability of the various forms of Cho needed to sustain
      cellular function). People who eat diets low in choline should deplete their choline (Cho)
      stores, and measurement of Cho pool size using isotope dilution should reflect this
      depletion. The investigators will identify a biomarker panel that correlates well with
      measured Cho pool size across the range of different degrees of depletion. This study tests a
      method for using stable isotope dilution to measure body choline stores, and then asks how
      this measure correlates with a panel of biomarkers in plasma and with liver fat measured
      using Fibroscan®. Using isotope dilution can provide an estimate of the size of the body pool
      of Cho. The investigators' proposed method is conceptually similar to the method for
      measuring total body water from a bolus dose of labeled water. Similar methodology was used
      recently in studies of metabolic flux of Cho in pregnant women. Isotope dilution is a
      well-established method used to estimate pool size for other nutrients, such as vitamin A.
      Similar to vitamin A, the major storage pools for Cho are in the liver, and ingested Cho is
      rapidly absorbed and accumulated by liver. MRS/MRI scans will also be performed to
      investigate correlation between these "gold standard" measures and the other methods
      described above.

      Participants will consume meals provided in two week dietary intervals with 3 different
      levels of choline with a 2 week washout periods between those dietary intervals. Participants
      will receive 100% of the recommended intake (RDI) of Cho (550mg Cho/day); 50% of the RDI of
      Cho (275mg/day); and 25% of the RDI of Cho (137.5mg/day). The meal order will be randomly
      assigned and all participants will receive all diets at some point in the study. There will
      be a minimum of a two week washout between diet intervals. Both participants and researchers
      will be blinded to the diet order.

      Participants will have brief exercise challenges (Biodex) to assess muscle function as an
      additional predictor of choline status.

      Participants enrolled prior to 3/2020 completed MRI/MRS scans. We have determined that
      Fibroscan provides adequate measurement of liver fat such that we eliminated the added
      inconvenience to participants of travel to Winston-Salem for MR scanning.

      Saliva, stool, and urine samples will be collected.
    

Intervention name(s): 25% Cho diet; 50% Cho diet; 100% Cho diet
Intervention type(s): Other; Other; Other
Intervention description(s): Subjects will consume meals containing 25% of recommended intake of Choline for 2 weeks. On day 12 of the diet period, subjects will consume 250 mg of Cho in the form of Cho chloride (trimethyl-d9, 9%), Cambridge Isotope Laboratories, Tewksbury, Massachusetts, (USA), as a bolus.; Subjects will consume meals containing 50% of recommended intake of Choline for 2 weeks. On day 12 of the diet period, subjects will consume 250 mg of Cho in the form of Cho chloride (trimethyl-d9, 9%), Cambridge Isotope Laboratories, Tewksbury, Massachusetts, (USA), as a bolus.; Subjects will consume meals containing 100% of recommended intake of Choline for 2 weeks. On day 12 of the diet period, subjects will consume 250 mg of Cho in the form of Cho chloride (trimethyl-d9, 9%), Cambridge Isotope Laboratories, Tewksbury, Massachusetts, (USA), as a bolus.
Other intervention name(s): 137.5mg Choline/day; 275mg Choline/day; 550mg Choline/day
Intervention MeSH terms: Choline
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: Healthy volunteers will consume meals, provided by the investigator, in two week intervals with 3 different levels of choline (Cho). Participants will receive 100% of the recommended daily intake (RDI) of Cho (550 mg Cho/day); 50% of the RDI of Cho (275mg/day); and 25% of the RDI of Cho (137.5 mg/day). The meal order will be randomly assigned and all participants will receive all diets at some point in the study. There will be a minimum of a two week washout between diet intervals where participants return to their regular diets. Both participants and researchers will be blinded to the diet order.
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary purpose: Screening