Phenylalanine Requirement of Adults >65 Years.

Study Overview
=================
Brief Summary
-----------------
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.

Detailed Description
-----------------
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. To compare the requirement so derived to that of young healthy adult previously determined in our lab.

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

Conditions
-----------------
Older Adults

Intervention / Treatment
-----------------
* Dietary Supplement: Phenylalanine intake


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Healthy elderly males and females > 65 years Willingness to participate in the study and completed the screening procedures (height, weight, fasting blood sample and medical history questionnaire). No recent history of weight loss 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. Non-smoking Willingness to consume the diet provided Exclusion Criteria: 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). On medications known to affect protein and amino acid metabolism (steroids). Recent significant weight loss. Individual on weight reducing diets. Inability to tolerate the diet Unwilling to have blood drawn from a venous access, or using a ventilated hood indirect calorimeter for the purposes of the study. Significant coffee consumption of more than 2 cups/day Significant alcohol consumption of more than one drink/day

Ages Eligible for Study
-----------------
Minimum Age: 65 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Design Details

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


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Adult Males >65 years<br>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<br>* Phenylalanine will be provided as graded intakes ranging from 7-40 mg/kg/day<br>|
| Experimental: Adult Females >65 years<br>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<br>* Phenylalanine will be provided as graded intakes ranging from 7-40 mg/kg/day<br>|

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 | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
Elderly, Phenylalanine, Healthy