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Trial registered on ANZCTR


Registration number
ACTRN12615001134516
Ethics application status
Approved
Date submitted
25/09/2015
Date registered
27/10/2015
Date last updated
1/08/2018
Type of registration
Prospectively registered

Titles & IDs
Public title
Dietary protein digestion and absorption kinetics and subsequent postprandial muscle protein accretion in healthy older people
Scientific title
Dietary protein digestion and absorption kinetics and subsequent postprandial muscle protein accretion in healthy older people
Secondary ID [1] 287499 0
Nil
Universal Trial Number (UTN)
Nil
Trial acronym
Nil
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Anorexia of ageing 296250 0
Condition category
Condition code
Diet and Nutrition 296520 296520 0 0
Other diet and nutrition disorders

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
The study will involve 20 healthy older men (age: greater than 65y, BMI 22-30kg/m2). Recruitment will be by (i) advertisement and (ii) from databases of our previous studies. Subjects will attend the Discipline of Medicine, Royal Adelaide Hospital, for an initial screening visit where inclusion and exclusion criteria will be evaluated, and the following baseline measurements will be obtained: body composition (DEXA), and biochemistry screen. Subjects will be asked to refrain from exercise and complete a food diary to determine their energy and protein intake during the 2 days before the study day.
Subjects will be studied on 1 study day to determine the effects of intraduodenal (ID) administration (at a rate of 4mL/min; 240mL over 60min) of i) milk protein intrinsically labelled with L-[1-13C]-phenylalanine and L-[1-13C]-leucine (25g, 100kcal, 1.7 kcal/min), or ii) amino acid mixture matching (isocaloric) the milk protein including L-[1-13C]-phenylalanine and L-[1-13C]-leucine; on absorption and digestion kinetics; muscle protein fractional synthetic rates; antropyloroduodenal (ADP) pressures and; appetite and gastrointestinal symptoms, in a randomized, double-blind, parallel study design, with 10 subjects in each group.
Subjects will be provided with a standardized evening meal to consume on the night before the study, and will be instructed to fast overnight from solids and liquids and to refrain from strenuous physical activity until they attend the laboratory at 0800am. On arrival, a Teflon catheter will be inserted in an antecubital vein for stable isotope infusion. A second Teflon catheter will be inserted in an antecubital vein of the contralateral arm for blood sampling. The plasma phenylalanine pools will be primed with a single intravenous dose containing L-[ring-2 H5 ]-phenylalanine (2.2 micromol/kg), L-[3,5-D2]-tyrosine (0.674 micromol/kg), and L-[1-13C]-leucine (4.391 micromol/kg) after which continuous intravenous infusion with the same tracers will be started for the rest of the study day until t=360min (L-[ring-2 H5 ]phenylalanine: 0.055 micromol/kg/min; L-[3,5-D2]-tyrosine: 0.017 micromol/kg/min; L-[1-13C]-leucine: 0.110 micromol/kg/min). A small-diameter, manometric catheter will be inserted into the stomach through an anesthetized nostril and allowed to pass into the duodenum by peristalsis. The correct positioning of the catheter will be maintained by continuous measurement of the transmucosal potential difference (TMPD). The intraduodenal protein infusion will start at t=0, ~120min after commencement of the intravenous infusion, once baseline ADP motility has been recorded for ~15min. During the 60min ‘protein’ infusion, ADP motility will be measured continuously (0-60min). Blood samples will be drawn, visual analog scale (VAS) questionnaires to assess perceptions of appetite and gastrointestinal symptoms will be completed, at -150, -60, -30, 0, 15, 30, 45, 60, 90, 120, 150, 180, 240, 300, 360 min. Muscle biopsies (~55mg) will be collected from the middle region of the vastus lateralis muscle at 0 and 180 min. After completion of a meal, subjects will be allowed to leave the laboratory.
Intervention code [1] 292883 0
Prevention
Comparator / control treatment
Amino acid mixture matching (isocaloric) the milk protein including L-[1-13C]-phenylalanine and L-[1-13C]-leucine
Control group
Active

Outcomes
Primary outcome [1] 296142 0
Muscle protein fractional synthetic rates
Timepoint [1] 296142 0
Muscle biopsies will be taken 10 minutes before (t=-10 min) the start of the intraduodenal infusion, and 6 hours after (t=360 min) the start of the intraduodenal infusion.
Primary outcome [2] 296143 0
Plasma phenylalanine concentrations
Timepoint [2] 296143 0
Muscle biopsies will be taken 10 minutes before (t=-10 min) the start of the intraduodenal infusion, and 6 hours after (t=360 min) the start of the intraduodenal infusion.
Blood samples will be taken at t= -150, -60, -30, 0, 15, 30, 45, 60, 90, 120, 150, 180, 240, 300, and 360 min, where t=0 is at commencement of the ID protein infusion.
Primary outcome [3] 296144 0
Plasma leucine concentrations
Timepoint [3] 296144 0
Muscle biopsies will be taken 10 minutes before (t=-10 min) the start of the intraduodenal infusion, and 6 hours after (t=360 min) the start of the intraduodenal infusion.
Blood samples will be taken at t= -150, -60, -30, 0, 15, 30, 45, 60, 90, 120, 150, 180, 240, 300, and 360 min, where t=0 is at commencement of the ID protein infusion.
Secondary outcome [1] 318060 0
Plasma amino acid concentrations
Timepoint [1] 318060 0
Blood samples will be taken at t= -150, -60, -30, 0, 15, 30, 45, 60, 90, 120, 150, 180, 240, 300, and 360 min, where t=0 is at commencement of protein ID infusion.
Secondary outcome [2] 318062 0
Plasma PYY concentrations
Timepoint [2] 318062 0
Blood samples will be taken at t= -150, -60, -30, 0, 15, 30, 45, 60, 90, 120, 150, 180, 240, 300, and 360 min, where t=0 is at commencement of the ID protein infusion.
Secondary outcome [3] 318064 0
Plasma ghrelin concentrations
Timepoint [3] 318064 0
Blood samples will be taken at t= -150, -60, -30, 0, 15, 30, 45, 60, 90, 120, 150, 180, 240, 300, and 360 min, where t=0 is at commencement of the ID protein infusion.
Secondary outcome [4] 318065 0
Plasma GLP-1 concentrations
Timepoint [4] 318065 0
Blood samples will be taken at t= -150, -60, -30, 0, 15, 30, 45, 60, 90, 120, 150, 180, 240, 300, and 360 min, where t=0 is at commencement of the ID protein infusion.
Secondary outcome [5] 318066 0
Plasma GIP concentrations
Timepoint [5] 318066 0
Blood samples will be taken at t= -150, -60, -30, 0, 15, 30, 45, 60, 90, 120, 150, 180, 240, 300, and 360 min, where t=0 is at commencement of the ID protein infusion.
Secondary outcome [6] 318067 0
Plasma CCK concentrations
Timepoint [6] 318067 0
Blood samples will be taken at t= -150, -60, -30, 0, 15, 30, 45, 60, 90, 120, 150, 180, 240, 300, and 360 min, where t=0 is at commencement of the ID protein infusion.
Secondary outcome [7] 318069 0
Plasma insulin concentrations
Timepoint [7] 318069 0
Blood samples will be taken at t= -150, -60, -30, 0, 15, 30, 45, 60, 90, 120, 150, 180, 240, 300, and 360 min, where t=0 is at commencement of the ID protein infusion.
Secondary outcome [8] 318070 0
Plasma glucagon concentrations
Timepoint [8] 318070 0
Blood samples will be taken at t= -150, -60, -30, 0, 15, 30, 45, 60, 90, 120, 150, 180, 240, 300, and 360 min, where t=0 is at commencement of the ID protein infusion.
Secondary outcome [9] 318071 0
Blood glucose concentrations
Timepoint [9] 318071 0
Blood samples will be taken at t= -150, -60, -30, 0, 15, 30, 45, 60, 90, 120, 150, 180, 240, 300, and 360 min, where t=0 is at commencement of the ID protein infusion.
Secondary outcome [10] 318072 0
Appetite
Timepoint [10] 318072 0
Visual analogue scales will be completed at t= -150, -60, -30, 0, 15, 30, 45, 60, 90, 120, 150, 180, 240, 300, and 360 min, where t=0 is at commencement of the ID protein infusion.
Secondary outcome [11] 318073 0
Gastrointestinal symptoms
Timepoint [11] 318073 0
Visual analogue scales will be completed at t= -150, -60, -30, 0, 15, 30, 45, 60, 90, 120, 150, 180, 240, 300, and 360 min, where t=0 is at commencement of the ID protein infusion.
Secondary outcome [12] 318074 0
Antropyloroduodenal (ADP) pressure waves
Timepoint [12] 318074 0
ADP pressure waves will be observed and recorded during the baseline period (t=-15 - t=0), and during the intraduodenal infusion (t=0 - t=60) using the ID cathether.
Secondary outcome [13] 318075 0
Energy intake at buffet meal
Timepoint [13] 318075 0
Buffet meal is presented at 360 minutes after preload consumption and the subject is allowed to freely consume food until comfortably full for 30 minutes (until t= 390 minutes). The weight of the foods will be recorded before and after it is offered to the subjects and energy intake and macronutrient composition calculated subsequently using commercially available software (Foodworks 3.01, Xyris Software, Highgate Hill, QLD, Australia).

Eligibility
Key inclusion criteria
Body Mass Index (BMI): 22-30 kg/m2

Weight stable (<5% fluctuation in body weight in previous 3 months)

Age >65
Minimum age
65 Years
Maximum age
No limit
Sex
Males
Can healthy volunteers participate?
Yes
Key exclusion criteria
smokers of cigarettes/cigars/marijuana;

intake of >2 standard drinks on >5 days per week;

intake of >4 cups of caffeinated drinks per day;

intake of any illicit substance;

vegetarians;

lactose intolerance;

Use of prescribed or non-prescribed medications (including vitamins and herbal supplements) which may effect gastrointestinal function or appetite - if subjects are willing, and able, to stop using medications, vitamins and/or supplements which affect gastrointestinal or energy metabolism during the study a washout period of at least 14 days prior to the first test day will apply;

food allergy(s), diabetes mellitus (fasting glucose >6.9 mmol/L), epilepsy, or gallbladder, pancreatic, cardiovascular or respiratory diseases;

significant gastrointestinal symptoms, disease or surgery (apart from uncomplicated appendectomy), as determined by a questionnaire;

impaired cognitive function (score <25 on Mini-Mental State Examination);

depression (a score >11 on the Geriatric Depression Questionnaire);

any other illness deemed significant by the investigator (including chronic illnesses not explicitly listed above);

low ferritin levels (<20ug/l) and plasma Hb levels (<130g/l), or blood donated in the 12 weeks prior to taking part in the study, in line with current Australian Red Cross Guidelines;

individuals who are found to be unable to comprehend the study protocol.

Study design
Purpose of the study
Prevention
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Volunteers are asked to visit the clinic for a screening visit. A series of screening questionnaires are answered by the volunteer, and a blood sample is taken for determination of ferritin and HBA1C levels. Eligibility is determined based on the inclusion/exclusion criteria. A signed informed consent form is obtained and study dates are established. Eligible volunteers are assigned a subject number and randomised into a treatment the study visit using a randomisation table. Randomisation involves contacting the holder of the randomisation table (study assistant) to inform them of the subjects details and study dates. The unblinded study assistant is therefore responsible for allocating a random treatment to the subject and preparing the intraduodenal infusion on the study day.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
The randomisation table was created using http://www.randomization.com/
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s
The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Parallel
Other design features
Phase
Type of endpoint/s
Statistical methods / analysis

Recruitment
Recruitment status
Withdrawn
Reason for early stopping/withdrawal
Lack of funding/staff/facilities
Date of first participant enrolment
Anticipated
1/11/2015
Actual
Date of last participant enrolment
Anticipated
1/12/2016
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
20
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
SA
Recruitment hospital [1] 4360 0
The Royal Adelaide Hospital - Adelaide
Recruitment postcode(s) [1] 10590 0
5000 - Adelaide

Funding & Sponsors
Funding source category [1] 292073 0
Charities/Societies/Foundations
Name [1] 292073 0
Royal Adelaide Hospital Research Foundation - Clinical Project Grant
Country [1] 292073 0
Australia
Primary sponsor type
Individual
Name
Stijn Soenen
Address
Discipline of Medicine, University of Adelaide
Attn.: Stijn Soenen
Level 6 Eleanor Harrald Building,
Frome Road,
Adelaide, SA 5000
Country
Australia
Secondary sponsor category [1] 290748 0
University
Name [1] 290748 0
The University of Adelaide
Address [1] 290748 0
North Terrace
Adelaide, SA, 5000
Country [1] 290748 0
Australia

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 293557 0
Royal Adelaide Hospital Research Ethics Committee
Ethics committee address [1] 293557 0
Level 3, Hanson Institute, North Terrace
Adelaide, South Australia, 5000
Ethics committee country [1] 293557 0
Australia
Date submitted for ethics approval [1] 293557 0
Approval date [1] 293557 0
12/06/2015
Ethics approval number [1] 293557 0
HREC/15/RAH/153

Summary
Brief summary
Older people are more likely to lose than gain weight and weight loss is a strong predictor of poor outcomes in older people. Weight lost in older people predominantly comprises muscle and insufficient protein intake is likely to exacerbate muscle loss by limiting muscle anabolism. When severe, muscle loss leads to sarcopenia or cachexia, which are strongly associated with adverse outcomes.
Protein-enriched supplements are often used to preserve and restore skeletal muscle mass in the elderly population. The rationale for using protein supplements in older people is strengthened by evidence that ageing has a minimal effect on the capacity to synthesize muscle protein acutely after protein ingestion. Accordingly if older people can ingest enough protein it is likely to have beneficial effects on muscle mass. Muscle protein deposition and anabolic effects are greater when amino acid concentrations are higher, however, there are limits to the amount of protein that can be chronically ingested, particularly by older people, due to factors such as cost, palatability and suppression of energy intake at subsequent meals. Furthermore, in young adults, the onset of satiety after ingestion of more rapidly digested and absorbed proteins is earlier, and its duration shorter than with ‘slower’ proteins. Administration of more rapidly absorbed proteins to under-nourished older people may, therefore, have the advantages of not only enhancing muscle protein synthesis, but also of minimising the duration of any potentially appetite suppressant effects.
An effective way to increase muscle protein deposition, by accelerating the absorption of proteins, may be to hydrolyse them, ie digest proteins in their component amino acids. In healthy older people, for example, administration of partially hydrolysed casein resulted in earlier and higher peak amino acids (particularly essential amino acids, e.g. ~3-fold increase in peak plasma leucine concentration) than administration of the same amounts of un-hydrolysed casein (~2-fold increase). Insights into the digestion and absorption kinetics of dietary protein-derived amino acids after protein ingestion can successfully be obtained by using cow milk protein with intrinsically labelled amino acids (L-[1-13C]-phenylalanine and L-[1-13C]-leucine), which are measured in muscle biopsies after administration to calculate fractional synthetic rates of the muscle.
Aim: To determine the acute effects of hydrolysis of protein on protein absorption and digestion kinetics of milk protein, administered directly into the small intestine.
Hypothesis: In older subjects the plasma amino acid concentrations will peak more rapidly and the muscle protein deposition will be higher after ingestion of the completely digested protein (free amino acids) when compared with the intact intrinsically-labelled milk protein.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 60442 0
Dr Stijn Soenen
Address 60442 0
Discipline of Medicine, University of Adelaide Attn.: Stijn Soenen Level 6 Eleanor Harrald Building, Frome Road, Adelaide, SA 5000
Country 60442 0
Australia
Phone 60442 0
+61 8 8313 3638
Fax 60442 0
+61 8 8223 3870
Email 60442 0
[email protected]
Contact person for public queries
Name 60443 0
Stijn Soenen
Address 60443 0
Discipline of Medicine, University of Adelaide Attn.: Stijn Soenen Level 6 Eleanor Harrald Building, Frome Road, Adelaide, SA 5000
Country 60443 0
Australia
Phone 60443 0
+61 8 8313 3638
Fax 60443 0
+61 8 8223 3870
Email 60443 0
[email protected]
Contact person for scientific queries
Name 60444 0
Stijn Soenen
Address 60444 0
Discipline of Medicine, University of Adelaide Attn.: Stijn Soenen Level 6 Eleanor Harrald Building, Frome Road, Adelaide, SA 5000
Country 60444 0
Australia
Phone 60444 0
+61 8 8313 3638
Fax 60444 0
+61 8 8223 3870
Email 60444 0
[email protected]

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