Defining Protein Requirements in Adults With PKU: Impact of Genotype and Medical Food Intake
Emory University
Summary
The objective of this research is to determine the protein requirements based on genotype and medical food consumption in a sample of adults with Phenylketonuria (PKU) using the indicator amino acid oxidation (IAAO) method.
Description
Current phenylketonuria (PKU) protein guidelines are based on outdated methods and do not account for differences in genetics or how much medical formula an individual consumes. This research aims to determine more accurate and personalized protein requirements in adults with PKU that have different genetic changes using a safe and direct method called the indicator amino acid oxidation technique. The study will address two specific aims: Aim 1 will determine the protein requirements of adults with PKU that have different genetic changes and Aim 2 will investigate how the ratio of medical form…
Eligibility
- Age range
- 18+ years
- Sex
- All
- Healthy volunteers
- No
Inclusion Criteria: * will be males and females (50:50) 18 years and older who were diagnosed with PKU through newborn screening or diagnosis later in life, capable of providing consent, and have previously had mutation testing Exclusion Criteria: * include concurrent illness, recent history of weight loss or acute illness during the past 6 months that could affect protein metabolism, pregnancy, lack of regular menstruation, implantable electronic devices or pacemakers, history of claustrophobia, and inability to provide consent. In addition, participants will be excluded if their genotype…
Interventions
- OtherNonradioactive stable oral isotope
NaH13CO3 \[99% atom percent excess (APE) and L-\[1-13C\]Leu (99% APE) will be given orally. Isotope administration will begin with the fifth meal on each study day with each remaining meal. The nonradioactive stable oral isotope is being administered to study the physiological process of amino acid oxidation.
- OtherTest diet
Test diets will be provided on study days in 8 hourly isocaloric and isonitrogenous meals to maintain a metabolic steady state. Each meal will provide one-twelfth of the participant's daily needs to model a 12-hour fasted and 12-hour fed feeding pattern. The diet will be composed of PFD2 (Mead Johnson), Tang and Kool-Aid (Kraft), corn oil, and protein-free wheat starch cookies. Each participant will receive 1 of 7 test protein intakes (0.2-3.2 g ⋅ kg-1 ⋅ d-1) on each study day. Protein will be provided as a crystalline L-amino acid mixture based on an egg protein pattern. Phe will be provided separately based on the Phe tolerance for each patient established by the metabolic dietitian listed on the IRB protocol. Leucine will be provided at a constant amount of 82.6 mg/kg/day as it is used as the indicator amino acid. The medical food used in this study is being fed to subjects for nutritional purposes to study the oxidation of the nonradioactive oral isotope.
Location
- Emory University HospitalAtlanta, Georgia