Fate of Nutrient-Derived Amino Acids, FONDAA

Study Overview
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Brief Summary
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12 elderly (65-70 years of age) male subjects will be included and complete a double blinded cross-over study. They will be habituated for 21 days to either low or high protein intake (below 0.8 g/kg or above 1.5 g/kg, respectively). Following a 45 day washout period they will switch to the alternate group. At the end of each habituation period, the investigators will measure the appearance of labelled amino acids from milk proteins.

Official Title
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Fate of Nutrient-Derived Amino Acids: Influence of Habituated Levels of Daily Dietary Protein Intake on Protein Utilization

Conditions
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Protein Utilization, Dietary Protein

Intervention / Treatment
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* Dietary Supplement: Meal serving at high dietary protein
* Dietary Supplement: Meal serving at low dietary protein
* Dietary Supplement: Meal serving


Participation Criteria
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Eligibility Criteria
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Exclusion Criteria: Hyperlipidemia Hypertension Inclusion Criteria: Males age 65-70 Independently dwelling Without any major health issues (blood pressure, cholesterol and lipid profile will be measured and evaluated by a physician) Non-diabetic No organ disease No back pain Not regularly take any prescription drugs or dietary supplements, which can influence muscle protein synthesis Alcohol intake below 21 units pr. week No known arthrosclerosis

Ages Eligible for Study
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Minimum Age: 65 Years
Maximum Age: 70 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Meal serving at high dietary protein<br>Test the handling of meal-served protein when habituated to high dietary protein at an amount above 1.5 g protein/kg/day | Dietary Supplement: Meal serving at high dietary protein<br>* Participants are habituated to a high level of dietary protein intake for 21 days.<br>Dietary Supplement: Meal serving<br>* To investigate impact of habituated protein level<br>|
| Active Comparator: Meal serving at low dietary protein<br>Test the handling of meal-served protein when habituated to high dietary protein at an amount below 0.8 g protein/kg/day | Dietary Supplement: Meal serving at low dietary protein<br>* Participants are habituated to a low level of dietary protein intake for 21 days.<br>Dietary Supplement: Meal serving<br>* To investigate impact of habituated protein level<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Abundance of milk protein-bound amino acid labels in blood protein. | Related to the trials conducted after 21 days of habituation to either high or low protein in the diet: After intake of milk proteins at time 0 (zero) the quantity of intrinsic labels D5-phe from whey and 15N-phe from casein will be measured in liver-synthesized blood protein at 240 min. | Baseline to 240 min postprandial | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Abundance of milk protein-bound amino acid labels in myofibrillar protein. | Related to the trials conducted after 21 days of habituation to either high or low protein in the diet: After intake of milk proteins at time 0 (zero) the quantity of intrinsic labels D5-phe from whey and 15N-phe from casein will be measured in myofibrillar protein at 240 min. | Baseline to 240 min postprandial | 
| Leg phenylalanine rate of disappearance and appearance, net balance. | Related to the trials conducted after 21 days of habituation to either high or low protein in the diet: From arterial and femoral venous blood samples obtained at baseline, 30, 60, 90, 120, 150, 180, 240 min phenylalanine tracer enrichments and concentrations as well as plasma flow will be measured. | Baseline to 240 min postprandial | 
| First pass splanchnic extraction of dietary protein-derived labeled phenylalanine. | Related to the trials conducted after 21 days of habituation to either high or low protein in the diet: From hepatic venous blood samples obtained at baseline, 30, 60, 90, 120, 150, 180, 240 min phenylalanine tracer enrichments and concentrations as well as plasma flow will be measured. Knowing the amount of ingested protein and labeled phenylalanine we can calculate the first pass splanchnic amino acid extraction. | Baseline to 240 min postprandial | 
| Whole body phenylalanine rate of disappearance and appearance, net balance. | Related to the trials conducted after 21 days of habituation to either high or low protein in the diet: From blood samples obtained at baseline, 30, 60, 90, 120, 150, 180, 240 min phenylalanine tracer enrichments will be measured. | Baseline to 240 min postprandial | 
| The myofibrillar protein fractional synthesis rate | Related to the trials conducted after 21 days of habituation to either high or low protein in the diet: From muscle biopsies obtained at baseline, 60 and 240 min the abundance of phenylalanine tracer bound in the myofibrillar proteins will be measured and the fractional synthesis rate will be measured within the first from baseline to 60 min and 240 min as well as from 60-240 min postprandial. | Baseline to 240 min postprandial | 
| Response of expression of proteins involved in muscle protein turnover | Related to the trials conducted after 21 days of habituation to either high or low protein in the diet: From baseline to 60 and 240 min after intake of the standardized meal after 21 days of habituation to either a high or a low dietary protein intake expression of signalling proteins related to protein turnover in the muscle will be measured by use of western blotting. | Baseline, 60 min and 240 min postprandial | 
| Urea production. | Related to the trials conducted after 21 days of habituation to either high or low protein in the diet: From blood samples obtained at baseline, 30, 60, 90, 120, 150, 180, 240 min urea tracer enrichments and concentrations will be measured. With this, and flow measurements, we can determine the rate of urea production. | Baseline to 240 min postprandial | 
| Nitrogen and creatinine excreted in urine | Related to the adaptation to the 21 day habituation period to either high or low protein in the diet as well as the response to the standardized trial meal: Nitrogen and creatinine content is measured in urine is collected for the last 24 h of the 21 day habituation period, as well as during the 240 min trial day and the remaining 20 hours of the trial day. | 21 days post intervention, 240 min postprandial and 24 hours post the day 21 trial day | 
| Fecal microbiota composition | Related to the adaptation to the 21 day habituation period to either high or low protein in the diet as well as the response to the standardized trial meal: The microbiota compositions, will be measured in fecal samples collected before the 21 day habituation period, after the 21 day habituation periode, as well as after the 240 min trial day | Change from pre-intervention to 21 days and 22 days (21 intervention days habituation and the standardized trial meal on day 21) | 
| Adaptation of expression of proteins involved in muscle protein turnover | Related to the adaptation to the 21 day habituation period to either high or low protein in the diet: Biopsies taken following the two 21 day habituation period will, by use of western blotting, be analysed for expression of signalling proteins involved in muscle protein turnover. | After 21 days of habituation to either a high or a low dietary protein intake. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Required dietary protein, Amino acid, Splanchnic extraction