Dietary Protein, Protein Utilization
Conditions
Keywords
Required dietary protein, Amino acid, Splanchnic extraction
Brief summary
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.
Interventions
DIETARY_SUPPLEMENTMeal serving at high dietary protein
Participants are habituated to a high level of dietary protein intake for 21 days.
DIETARY_SUPPLEMENTMeal serving at low dietary protein
Participants are habituated to a low level of dietary protein intake for 21 days.
DIETARY_SUPPLEMENTMeal serving
To investigate impact of habituated protein level
Sponsors
Bispebjerg Hospital
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
TRIPLE (Subject, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
MALE
Age
65 Years to 70 Years
Healthy volunteers
Yes
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Abundance of milk protein-bound amino acid labels in blood protein. | Baseline to 240 min postprandial | 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. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Leg phenylalanine rate of disappearance and appearance, net balance. | Baseline to 240 min postprandial | 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. |
| First pass splanchnic extraction of dietary protein-derived labeled phenylalanine. | Baseline to 240 min postprandial | 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. |
| Whole body phenylalanine rate of disappearance and appearance, net balance. | Baseline to 240 min postprandial | 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. |
| The myofibrillar protein fractional synthesis rate | Baseline to 240 min postprandial | 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. |
| Abundance of milk protein-bound amino acid labels in myofibrillar protein. | Baseline to 240 min postprandial | 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. |
| Urea production. | Baseline to 240 min postprandial | 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. |
| Nitrogen and creatinine excreted in urine | 21 days post intervention, 240 min postprandial and 24 hours post the day 21 trial day | 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. |
| Fecal microbiota composition | Change from pre-intervention to 21 days and 22 days (21 intervention days habituation and the standardized trial meal on day 21) | 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 |
| Adaptation of expression of proteins involved in muscle protein turnover | After 21 days of habituation to either a high or a low dietary protein intake. | 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. |
| Response of expression of proteins involved in muscle protein turnover | Baseline, 60 min and 240 min postprandial | 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. |
Countries
Denmark
Outcome results
None listed