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Trial registered on ANZCTR


Registration number
ACTRN12612000811808
Ethics application status
Approved
Date submitted
2/08/2012
Date registered
2/08/2012
Date last updated
31/10/2016
Type of registration
Retrospectively registered

Titles & IDs
Public title
The effects of small intestinal L-tryptophan infusions on gut motility, gut hormone release, blood glucose control and energy intake in humans.
Scientific title
The effects of small intestinal L-tryptophan infusions on antropyloroduodenal motility, gut hormone release, blood glucose control and energy intake in normal weight subjects.
Secondary ID [1] 280958 0
nil
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Obesity 287064 0
Healthy human physiology 287065 0
Condition category
Condition code
Diet and Nutrition 287387 287387 0 0
Obesity
Oral and Gastrointestinal 287388 287388 0 0
Normal oral and gastrointestinal development and function

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Regulation of the factors that control food intake, the function of the stomach and small intestine and release of gut hormones is complex, and our understanding of this field is far from complete. There is increasing evidence that nutrient stimuli in the gut, especially in the small intestine, induce changes in gut motor and hormonal functions that play a central role in the control of energy intake and blood glucose. In particular high-protein diets have been found to be very effective for weight loss and for improving blood glucose in obese with and without type 2 diabetes.
This study aims to investigate the effects of the amino acid, L-tryptophan on gut motility, gut hormone release, blood glucose control and energy intake in humans. We hypothesise that L-tryptophan, as building block of proteins, may substantially contribute to the beneficial effects of whole protein on gut functions and energy intake regulation. A total of 20 Caucasian male and female (BMI 18-25 kg/m2) subjects, aged between 18 - 50 years, will be included in the study. Each subject will be studied on three occasions. On each occasion, they will receive, in randomized, double-blind fashion, a 90-min intraduodenal infusion of (i) L-tryptophan at 0.2 kcal/min, (ii), L-tryptophan at 0.4 kcal/min (iii) L-tryptophan at 0.6 kcal/min or (iv) saline (negative control). Gut motility, blood glucose, gut hormones release, insulin concentrations, appetite perceptions and energy intake during a buffet meal, as well as vital signs, will be measured. The buffet meal will be provided at the end of the infusion and the participant has 30 minutes to eat until comfortably full. The buffet meal consists of 300ml orange juice, 600ml water, 375ml iced coffee, 4 slices white bread, 4 slices brown bread, 100g deli leg ham, 100g virginian chicken, 4 slices cheese, 100g tomato, 100g cucumber, 100g lettuce, 2 portions manyonnaise, 2 portions margarine, 1 medium apple, 1 medium banana, 200g chocolate custard, 150g fruit salad, 200g strawberry yoghurt, and 14g milky way chocolate bar. Each volunteer will receive one of each infusion solutions on each of the 4 study days. Each study visit will be separated by no less than 3 days.
Intervention code [1] 285397 0
Treatment: Other
Comparator / control treatment
saline
Control group
Placebo

Outcomes
Primary outcome [1] 287654 0
Antropyloroduodenal motility (number of antral, duodenal and isolated pyloric pressure waves, and basal pyloric pressure)
Timepoint [1] 287654 0
Using a manometri assembly and catheter, antropyloroduodenal pressures will be continously monitored from intubation until 90 minutes (end of infusion)
Primary outcome [2] 287657 0
Plasma concentrations of gastrointestinal hormones (e.g. CCK, GLP-1, PYY, GIP and ghrelin), insulin and glucose.
Timepoint [2] 287657 0
Gut hormone release will be assessed by Enzyme-linked Immunosorbent Assay (ELISA) or Radio Immnunosorbent Assay (RIA) from blood samples taken at t= -10, 0, 15, 30, 45, 60, 75, 90 & 120 minutes.
Secondary outcome [1] 298586 0
Appetite sensations using a Visual Analogue Scale (VAS) (satiety, hunger, fullness, thirst, desire to eat and amount of food desired to eat) and macronutrient and total energy intake at the buffet meal
Timepoint [1] 298586 0
VAS questionnaires are taken at t= -10, 0, 15, 30, 45, 60, 75, 90 & 120 minutes. The buffet meal will be presented at 90 minutes when the infusion ends and the subject will be allowed to freely consume food until comfortably full for 30 minutes (until t=120 minutes).

Eligibility
Key inclusion criteria
Male and female (BMI 18-25 kg/m2) subjects, aged between 18 - 50 years, will be included in the study. All subjects will be required to be weight-stable (i.e. < 5 % fluctuation in their body weight) at study entry, as determined by their self-reported weight in the preceding 3 months, and will be required to maintain their normal physical activity over the course of the study.
Minimum age
18 Years
Maximum age
50 Years
Gender
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Significant gastrointestinal symptoms, disease or surgery, use of prescribed or non-prescribed medications (including vitamins and herbal supplements) which may affect energy metabolism, gastrointestinal function, body weight or appetite (eg domperidone, orlistat, green tea extracts, Astragalus, St Johns Wort etc.), as well as SSRIs (selective serotonin reuptake inhibitors), lactose intolerance/other food allergy, diabetes mellitus, as defined by fasting glucose >6.9 mmol/l and/or glycated haemoglobin =6.2 %, epilepsy, cardiovascular or respiratory diseases, current intake of > 2 standard drinks on > 5 days per week, current smokers of cigarettes/cigars/marijuana, restrained eaters (score > 12 on the three factor eating questionnaire), vegetarians, in female subjects, pregnancy or lactation.

Study design
Purpose of the study
Treatment
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 30 minute screening visit. A questionnaire is answered by the volunteer, based on the inclusion/exclusion criteria and eligibility is determined. A signed informed consent is obtained and study dates are established. Eligible volunteers are assigned a subject number and randomised into a treatment for each study visit, using a randomisation table which was created on an excel spreadsheet. Randomisation involved contacting the holder (study assistant) of the randomisation table to inform them of the next subjects details and study dates. The unblinded study assistant is therefore responsible for allocating a random treatment to the subject and preparing the solution on each study day.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
The randomisation table was generated using Microsoft Office Excel.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?



Intervention assignment
Crossover
Other design features
Phase
Not Applicable
Type of endpoint(s)
Pharmacokinetics / pharmacodynamics
Statistical methods / analysis

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
SA

Funding & Sponsors
Funding source category [1] 285743 0
Hospital
Name [1] 285743 0
Gum Bequest Grant, Royal Adelaide Hospital Endocrine Unit
Address [1] 285743 0
North Terrace,
Adelaide, SA 5000
Country [1] 285743 0
Australia
Primary sponsor type
Individual
Name
Christine Feinle-Bisset
Address
Level 6 Eleanor Harrald Building,
Frome Road,
Adelaide, SA 5000
Country
Australia
Secondary sponsor category [1] 284569 0
Individual
Name [1] 284569 0
Robert E Steinert
Address [1] 284569 0
Level 6 Eleanor Harrald Building,
Frome Road,
Adelaide, SA 5000
Country [1] 284569 0
Australia

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 287748 0
Royal Adelaide Hospital Research Ethics Committee
Ethics committee address [1] 287748 0
Level 3, Hanson Institute
North Terrace
Adelaide SA, 5000
Ethics committee country [1] 287748 0
Australia
Date submitted for ethics approval [1] 287748 0
Approval date [1] 287748 0
25/04/2012
Ethics approval number [1] 287748 0
120417

Summary
Brief summary
Regulation of the factors that control food intake, the function of the stomach and small intestine and release of gut hormones is complex, and our understanding of this field is far from complete. There is increasing evidence that nutrient stimuli in the gut, especially in the small intestine, induce changes in gut motor and hormonal functions that play a central role in the control of energy intake and blood glucose. In particular high-protein diets have been found to be very effective for weight loss and for improving blood glucose in obese with and without type 2 diabetes. This study aims to investigate the effects of the amino acid, L-tryptophan, on gut motility, gut hormone release, blood glucose control and energy intake in humans. We hypothesise that L-tryptophan as building block of proteins, may substantially contribute to the beneficial effects of whole protein on gut functions and energy intake regulation. This has not been evaluated in detail and will be important in order to enhance our understanding of the mechanisms underlying the effects of dietary protein on eating control.
Trial website
Trial related presentations / publications
Steinert RE, Luscombe-Marsh ND, Little TJ, Standfield S, Otto B, Horowitz M, Feinle-Bisset C. Effects of intraduodenal infusion of L-tryptophan on ad libitum eating, antropyloroduodenal motility, glycemia, insulinemia and gut peptide secretion in healthy men. J Clin Endocrinol Metab. 2014, 99(9):3275–3284.
Public notes

Contacts
Principal investigator
Name 34524 0
Prof Prof Christine Feinle-Bisset
Address 34524 0
Discipline of Medicine, University of Adelaide
Level 6 Eleanor Harrald Building, Frome Road, Adelaide, South Australia 5000
Country 34524 0
Australia
Phone 34524 0
+61 8 8222 5247
Fax 34524 0
Email 34524 0
christine.feinle@adelaide.edu.au
Contact person for public queries
Name 17771 0
Dr Dr Robert E Steinert
Address 17771 0
Level 6 Eleanor Harrald Building,
Frome Road,
Adelaide, South Australia 5000
Country 17771 0
Australia
Phone 17771 0
+61 8 8222 5039
Fax 17771 0
Email 17771 0
robert.steinert@adelaide.edu.au
Contact person for scientific queries
Name 8699 0
Dr Dr Robert E Steinert
Address 8699 0
Level 6 Eleanor Harrald Building,
Frome Road,
Adelaide, South Australia 5000
Country 8699 0
Australia
Phone 8699 0
+61 8 8222 5039
Fax 8699 0
Email 8699 0
robert.steinert@adelaide.edu.au

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary