Phenylalanine Requirement of Adults >65 Years.

Phenylalanine Requirement of Healthy Older Adult Males and Females > 65 Years Determined by Direct Amino Acid Oxidation (DAAO) Method.

Currently there are insufficient published studies on amino acid requirements in the elderly. Phenylalanine is one of the indispensable amino acids. Low levels of phenylalanine has been observed in in the blood of older adults. It is due the increased uptake by the liver and intestine. This decreased levels of phenylalanine could lead to decreased skeletal muscle protein synthesis. Requirement for elderly individuals have been set based on studies conducted in younger adults hence may be inaccurate. The goal of this study is to directly measure the phenylalanine requirement of male and female elderly subjects over 65 years using the direct amino acid oxidation (DAAO) technique.

Study Overview

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

Detailed Description

1. To determine and compare the phenylalanine requirement of healthy elderly male and female adults over the age of 65 years using the DAAO technique (by measuring the oxidation of L-[1-13 C] phenylalanine to 13 CO 2 [F 13 CO 2] ) in response to graded intakes of phenylalanine.
2. To compare the requirement so derived to that of young healthy adult previously determined in our lab.

• Study Type: Interventional
• Enrollment (Actual): 20
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Canada
  • Ontario
    • Toronto, Ontario, Canada, M5G1X8
      • The Hospital for Sick Children

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 63 years and older (Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

1. Healthy elderly males and females > 65 years
2. Willingness to participate in the study and completed the screening procedures (height, weight, fasting blood sample and medical history questionnaire).
3. No recent history of weight loss
4. Absence of chronic disease or acute illness that could affect protein and AA metabolism (diabetes, cancer, liver or kidney disease, HIV, acute cold or flu, hypo or hyperthyroidism, rheumatoid arthritis treated with anti-inflammatory medications.
5. Non-smoking
6. Willingness to consume the diet provided

Exclusion Criteria:

1. Presence of disease known to affect protein and AA metabolism (diabetes, cancer, liver or kidney disease, HIV, acute cold or flu, hypo or hyperthyroidism, rheumatoid arthritis treated with anti-inflammatory medications).
2. On medications known to affect protein and amino acid metabolism (steroids).
3. Recent significant weight loss.
4. Individual on weight reducing diets.
5. Inability to tolerate the diet
6. Unwilling to have blood drawn from a venous access, or using a ventilated hood indirect calorimeter for the purposes of the study.
7. Significant coffee consumption of more than 2 cups/day
8. Significant alcohol consumption of more than one drink/day

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Adult Males >65 years; Participants will be seen initially for pre-study assessment (3 hour). They will then be studied weekly for up to 7 levels of phenylalanine intake (7 Study periods). Each study period will include a period of 3 days. The first 2 days they will consume a liquid milkshake based diet at home. On the 3rd day they will come to the hospital for a total of 8 hours.	Dietary supplement: Phenylalanine intake; Phenylalanine will be provided as graded intakes ranging from 7-40 mg/kg/day
Experimental: Adult Females >65 years; Participants will be seen initially for pre-study assessment (3 hour). They will then be studied weekly for up to 7 levels of phenylalanine intake (7 Study periods). Each study period will include a period of 3 days. The first 2 days they will consume a liquid milkshake based diet at home. On the 3rd day they will come to the hospital for a total of 8 hours.	Dietary supplement: Phenylalanine intake; Phenylalanine will be provided as graded intakes ranging from 7-40 mg/kg/day

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Phenylalanine Requirement	To determine phenylalanine requirement by measuring the oxidation of 13CO2 in breath in response to graded phenylalanine intakes	Baseline

Collaborators and Investigators

• Sponsor: The Hospital for Sick Children
• Investigators: Principal Investigator: Glenda Courtney-Martin, Hospital for Sick Children, Toronto, Ontario

Publications and helpful links

General Publications

• Martin KE, Pencharz PB, Rafii M, Ball RO, Szwiega S, Elango R, Courtney-Martin G. The Phenylalanine Requirement of Elderly Men and Women Measured by Direct 13C Carbon Oxidation Method Is Similar to That of Young Adults. J Nutr. 2019 Oct 1;149(10):1776-1784. doi: 10.1093/jn/nxz137.

Study record dates

Study Major Dates

• Study Start (Actual): August 1, 2016
• Primary Completion (Actual): June 1, 2018
• Study Completion (Actual): June 1, 2018

Study Registration Dates

• First Submitted: November 14, 2016
• First Submitted That Met QC Criteria: November 18, 2016
• First Posted (Estimate): November 22, 2016

Study Record Updates

• Last Update Posted (Actual): September 18, 2018
• Last Update Submitted That Met QC Criteria: September 14, 2018
• Last Verified: September 1, 2018

More Information

Terms related to this study

• Keywords: Elderly; Healthy; Phenylalanine
• Other Study ID Numbers: 1000051682

Plan for Individual participant data (IPD)

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