Metabolism, Protein
Conditions
Brief summary
The specific hypothesis is that the consumption of 2 Hayward green kiwifruit (containing actinidin protease) prior to 100g of ground beef will increase the rate of protein digestion from the beef in the elderly, leading to an increased uptake of the essential amino acids. Furthermore, this increased essential amino acid availability will produce a greater postprandial net anabolic protein response, as well as increased fractional synthetic rates of muscle proteins.
Detailed description
The specific hypothesis is that the consumption of 2 Hayward green kiwifruit (containing actinidin protease) prior to 100g of ground beef will increase the rate of protein digestion from the beef in the elderly, leading to an increased uptake of the essential amino acids. Furthermore, this increased essential amino acid availability will produce a greater postprandial net anabolic protein response, as well as increased fractional synthetic rates of muscle proteins. To test this hypothesis, the investigators will use a double-blinded crossover design involving two intervention arms; in both arms 100g of ground beef (cooked weight) will be consumed following either 2 Hayward green kiwifruit (containing actinidin protease) or 2 Hort16A Gold kiwifruit (devoid of actinidin protease) by elderly subjects.
Interventions
DIETARY_SUPPLEMENTGreen Hayward Kiwifruit first, then Gold Kiwifruit
Subjects ate 2 peeled green kiwifruit with their midday meal for 2 weeks prior to testing.
DIETARY_SUPPLEMENTGold Kiwifruit First, then Green Hayward Kiwifruit
Subjects ate 2 peeled gold kiwifruit with their midday meal for 2 weeks prior to testing.
Sponsors
University of Arkansas
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
OTHER
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)
Masking description
Biological samples were coded and code list password protected until all data was analyzed.
Intervention model description
Subjects crossed over between ingesting 2 different types of kiwifruit for 2 weeks prior to each stable isotope metabolic study.
Eligibility
Sex/Gender
ALL
Age
60 Years to 85 Years
Healthy volunteers
Yes
Inclusion criteria
* men and women ages 60-85 inclusive.
Exclusion criteria
* Inability to chew meats or difficulty swallowing solid foods * History of diabetes * History of malignancy in the 6 months prior to enrolment * History of gastrointestinal reduction or bypass surgery (Lapband, etc) * History of a chronic inflammatory condition or disease (Lupus, HIV'AIDS, etc) * History of chronic kidney disease or currently requiring dialysis. * Allergy to beef or kiwifruit * Subjects who do not or will not eat animal proteins * Subjects who cannot refrain from consuming protein or amino acid supplements during their participation in this study * Subjects who report regular resistance exercise (more than once per week) * Hemoglobin less than 9.5mg/dL at the screening visit * Platelets less than \<150,000 at the screening visit * Subjects who are not willing or able to suspend aspirin for several days prior to their muscle biopsies. * Subjects who have been prescribed a blood-thinning medication (Coumadin, lovenox, heparin, Plavix, etc). * Concomitant use of corticosteroids (ingestion, injection or transdermal) * Any other disease or condition that would place the subject at increased risk of harm if they were to participate, at the discretion of the study physician
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Whole Body Net Balance Measured by Gas Chromatography-Mass Spectrometry (GC-MS) | 300 minutes | Blood samples were analyzed to quantify the appearance of the stable isotopes: 2H2-tyrosine, 2H4-tyrosine, and 2H5-phenylalanine in tracer to tracee ratio or mole percent excess. Changes in these markers over time enable the calculation of whole body protein metabolism. Calculations are done as follows: Total plasma rate of appearance = infusion rate/enrichment Fractional rate of appearance of tyrosine from phenylalanine= 2H4-tyrosine/2H5-phenylalanine Phenylalanine hydroxylation = fractional rate of appearance of tyrosine from phenylalanine x rate of appearance of tyrosine Protein Synthesis = \[(rate of appearance of phenylalanine -Phe hydroxylation) x 25\] Protein Breakdown = \[(rate of appearance of phenylalanine - phenylalanine infusion rate) x 25 - phenylalanine intake\] Net Balance = Protein Synthesis - Protein Breakdown |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in Skeletal Muscle Protein Metabolism Measured by Gas Chromatography-Mass Spectrometry (GC-MS) | 9.5 hours | Muscle samples were analyzed to quantify the appearance of the stable isotope 2H5-phenylalanine in trace to tracee ratio or mole percent excess. The change in 2H5-phenylalanine in subsequent muscle biopsy allow for the calculation of muscle protein synthesis. The calculation is done as follows: \[(2H5-phenylalanine enrichment in second biopsy - 2H5-phenylalanine enrichment in second biopsy)/ (2H5-phenylalanine plasma enrichment × time)\] × 60 × 100. |
Countries
United States
Participant flow
Pre-assignment details
Protocol enrollment was 13 participants, each was to complete 2 conditions in crossover fashion (i.e., either green kiwi followed by yellow kiwi, or yellow kiwi followed by green kiwi). One subject dropped out, which left 6 subjects in each group.
Participants by arm
| Arm | Count |
|---|---|
| Gold Kiwifruit First, Then Green Hayward Kiwifruit Subjects were first asked to eat 2 gold kiwifruit with midday meal for 14 days prior to testing. Then a washout for 14 days. Then, subjects were asked to eat 2 green Hayward kiwifruit with midday meal for 2 weeks prior to a second set of testing. | 6 |
| Green Hayward Kiwifruit First, Then Gold Kiwifruit Subjects were first asked to eat 2 green Hayward kiwifruit with midday meal for 2 weeks prior to testing. Then a washout for 14 days. Then, subjects were asked to eat 2 gold kiwifruit with midday meal for 2 weeks prior to a second set of testing. | 6 |
| Total | 12 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 |
|---|---|---|---|
| Overall Study | Didn't Qualify | 1 | 0 |
Baseline characteristics
| Characteristic | Green Hayward Kiwifruit First, Then Gold Kiwifruit | Total | Gold Kiwifruit First, Then Green Hayward Kiwifruit |
|---|---|---|---|
| Age, Categorical <=18 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical >=65 years | 6 Participants | 10 Participants | 4 Participants |
| Age, Categorical Between 18 and 65 years | 0 Participants | 2 Participants | 2 Participants |
| Age, Continuous | 72.1 years STANDARD_DEVIATION 6.2 | 72.1 years STANDARD_DEVIATION 6.2 | 72.1 years STANDARD_DEVIATION 6.2 |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Asian | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Black or African American | 0 Participants | 2 Participants | 2 Participants |
| Race (NIH/OMB) More than one race | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) White | 6 Participants | 10 Participants | 4 Participants |
| Region of Enrollment United States | 6 participants | 12 participants | 6 participants |
| Sex: Female, Male Female | 4 Participants | 6 Participants | 2 Participants |
| Sex: Female, Male Male | 2 Participants | 6 Participants | 4 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | 0 / 12 | 0 / 12 |
| other Total, other adverse events | 1 / 12 | 0 / 12 |
| serious Total, serious adverse events | 0 / 12 | 0 / 12 |
Outcome results
Primary
Whole Body Net Balance Measured by Gas Chromatography-Mass Spectrometry (GC-MS)
Blood samples were analyzed to quantify the appearance of the stable isotopes: 2H2-tyrosine, 2H4-tyrosine, and 2H5-phenylalanine in tracer to tracee ratio or mole percent excess. Changes in these markers over time enable the calculation of whole body protein metabolism. Calculations are done as follows: Total plasma rate of appearance = infusion rate/enrichment Fractional rate of appearance of tyrosine from phenylalanine= 2H4-tyrosine/2H5-phenylalanine Phenylalanine hydroxylation = fractional rate of appearance of tyrosine from phenylalanine x rate of appearance of tyrosine Protein Synthesis = \[(rate of appearance of phenylalanine -Phe hydroxylation) x 25\] Protein Breakdown = \[(rate of appearance of phenylalanine - phenylalanine infusion rate) x 25 - phenylalanine intake\] Net Balance = Protein Synthesis - Protein Breakdown
Time frame: 300 minutes
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Gold Kiwifruit | Whole Body Net Balance Measured by Gas Chromatography-Mass Spectrometry (GC-MS) | 14.58 g protein per 300 mins | Standard Deviation 4.31 |
| Green Hayward Kiwifruit | Whole Body Net Balance Measured by Gas Chromatography-Mass Spectrometry (GC-MS) | 14.55 g protein per 300 mins | Standard Deviation 3.24 |
Secondary
Change in Skeletal Muscle Protein Metabolism Measured by Gas Chromatography-Mass Spectrometry (GC-MS)
Muscle samples were analyzed to quantify the appearance of the stable isotope 2H5-phenylalanine in trace to tracee ratio or mole percent excess. The change in 2H5-phenylalanine in subsequent muscle biopsy allow for the calculation of muscle protein synthesis. The calculation is done as follows: \[(2H5-phenylalanine enrichment in second biopsy - 2H5-phenylalanine enrichment in second biopsy)/ (2H5-phenylalanine plasma enrichment × time)\] × 60 × 100.
Time frame: 9.5 hours
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Gold Kiwifruit | Change in Skeletal Muscle Protein Metabolism Measured by Gas Chromatography-Mass Spectrometry (GC-MS) | 0.0043 % per hour | Standard Deviation 0.0244 |
| Green Hayward Kiwifruit | Change in Skeletal Muscle Protein Metabolism Measured by Gas Chromatography-Mass Spectrometry (GC-MS) | 0.0081 % per hour | Standard Deviation 0.0393 |
p-value: 0.05t-test, 2 sided