Determining Total Aromatic Amino Acid Requirements in Pregnant Women
Condition: Pregnancy Related
Study type: Interventional

Summary: 
      Phenylalanine and tyrosine are aromatic amino acids that people need to obtain in their
      diets. Amino acids are the building blocks for protein, are are therefore required to form
      tissues in the body. It is well known that pregnant women require more protein in their
      diets, but the exact amount for each amino acid is undetermined. To find out how much of
      phenylalanine and tyrosine pregnant women require, the investigators plan to study pregnant
      women in early and late gestation with a modern minimally invasive technique.
    

Detailed description: 
      Following a study to determine phenylalanine requirements in pregnant women, the
      investigator's purpose for this study is to determine the phenylalanine and tyrosine
      requirements (also know as the total aromatic amino acid requirement) in healthy pregnant
      women as part of a Doctoral Thesis project. The determined requirements can be taken into
      account when giving dietary recommendations, to ensure healthy pregnancies. The hypothesis is
      that the current recommendations for phenylalanine and tyrosine intake given to pregnant
      women are underestimated. The investigators also hypothesize that the phenylalanine and
      tyrosine requirements at early stages of pregnancy will be lower than the requirements
      towards the later stages of pregnancy.

      Current dietary intake recommendations for the aromatic amino acids are based on factorial
      (mathematical) calculations and do not account for requirement differences between early and
      late pregnancy. Static recommendations throughout all stages of pregnancy are not appropriate
      because of the multitude of adaptations the human body goes through during gestation. Whether
      phenylalanine and tyrosine requirements differ between different stages of gestation is
      unknown. The DRI gives a recommendation for total aromatic amino acids of 36 mg/kg/d during
      pregnancy. The results from this study would allow for a more accurate recommendations in
      future DRIs.

      The investigators will recruit healthy pregnant women aged 20 to 40 in their 13th-19th week
      of gestation or 33rd to 39th week of gestation. Once they get in contact with the lab, an
      initial visit (pre-study) will take place. Here, the participants will be measured for their
      eligibility and taken through the consent form. They have to participate in a pre-study for
      each stage of pregnancy, if they wish to participate in both stages. If they meet all the
      criteria and agree to participate, they will return for up to four study days per stage of 8
      hours each. Therefore, if they are recruited during late pregnancy they are only able to
      participate in four study days in total. During these study days they will be fed protein
      shakes containing the stable isotope, and then oxidation of this isotope will be measured to
      determine a breakpoint (requirement) of phenylalanine. Breath samples, urine samples, and a
      small blood sample will be taken during the study day.
    

Intervention name(s): Aromatic Amino Acid Intake
Intervention type(s): Dietary Supplement
Intervention description(s): Intakes will be randomly chosen from a list of 8 doses of aromatic amino acids. Each intake will will be repeated approximately 4 times.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: nutrition; phenylalanine; tyrosine; stable isotope