Phenylalanine Requirements in Healthy Pregnant Women

Dietary Phenylalanine Requirements During Different Stages of Gestation in Healthy Pregnant Women

Phenylalanine is an essential amino acid that people need to obtain in their diets. Amino acids are the building blocks for protein, which is 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 pregnant women require, the investigators plan to study pregnant women in early and late gestation with a modern minimally invasive technique.

Study Overview

• Status: Completed
• Conditions: Pregnancy
• Intervention / Treatment: Dietary supplement: Phenylalanine intake

Detailed Description

The investigator's purpose is to determine the phenylalanine requirements in healthy pregnant women as part of a Master's 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 intake given to pregnant women are underestimated. The investigators also hypothesize that the phenylalanine requirements at early stages of pregnancy will be lower than the requirements towards the later stages of pregnancy.

Current dietary intake recommendations for phenylalanine 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 requirements differ between different stages of gestation is unknown. In addition, phenylalanine is the precursor for tyrosine, which is a conditionally indispensable amino acid. Together they are referred to as the aromatic amino acids. The DRI gives a recommendation for total aromatic amino acids (TAA, phenylalanine + tyrosine) of 36 mg/kg/d during pregnancy. Since this study is the first interested in phenylalanine requirements during pregnancy, the investigators will determine the phenylalanine requirements in the presence of excess tyrosine (61 mg/kg/d) during pregnancy, similar to earlier studies.

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 two study days per stage of 8 hours each. Therefore, if they are recruited during late pregnancy they are only able to participate in two 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.

• Study Type: Interventional
• Enrollment (Actual): 23
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Canada
  • British Columbia
    • Vancouver, British Columbia, Canada, V5Z4H4
      • BC Children's Hospital Research Institute, University of British Columbia

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 16 years to 36 years (Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: Female

Description

Inclusion Criteria:

• over the age of twenty
• under the age of forty
• in overall good health
• pregnant with a single child

Exclusion Criteria:

• Be under the age of twenty
• Be over the age of forty
• Be pregnant with more than one child
• Have a history of cardiovascular disease, endocrine disorders, or metabolic disorders
• Have recently lost a substantial amount of weight
• Delivered a baby in the last 18 months
• Be substance dependent
• Be allergic to eggs
• Have severe nausea through the pregnancy
• Have gestational diabetes
• Have a history of spontaneous abortions
• Have had an unhealthy pre-pregnancy body mass index

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Other: Experimental: phenylalanine intake; Dietary supplement: phenylalanine intake	Dietary supplement: Phenylalanine intake; Oral consumption of eight hourly experimental meals- Includes 4 tracer-free experimental meals containing a mixture of free amino acids, calories from a flavored liquid and protein free cookies and 4- labeled amino acid experimental meals.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
13C Phenylalanine Oxidation	Urine, breath and a single blood sample will be collected during the study to measure the rate of oxidation of 13C phenylalanine.	8 hours

Collaborators and Investigators

• Sponsor: University of British Columbia
• Collaborators: Canadian Institutes of Health Research (CIHR)
• Investigators: Principal Investigator: Rajavel Elango, Ph.D., University of British Columbia

Publications and helpful links

General Publications

• Ennis MA, Rasmussen BF, Lim K, Ball RO, Pencharz PB, Courtney-Martin G, Elango R. Dietary phenylalanine requirements during early and late gestation in healthy pregnant women. Am J Clin Nutr. 2020 Feb 1;111(2):351-359. doi: 10.1093/ajcn/nqz288.

Study record dates

Study Major Dates

• Study Start (Actual): January 1, 2016
• Primary Completion (Actual): May 30, 2018
• Study Completion (Actual): October 30, 2019

Study Registration Dates

• First Submitted: November 30, 2015
• First Submitted That Met QC Criteria: January 27, 2016
• First Posted (Estimate): February 1, 2016

Study Record Updates

• Last Update Posted (Actual): November 14, 2019
• Last Update Submitted That Met QC Criteria: November 12, 2019
• Last Verified: November 1, 2019

More Information

Terms related to this study

• Keywords: Stable isotopes; Phenylalanine; Direct Amino Acid Oxidation
• Other Study ID Numbers: H15-02558

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No