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Trial details imported from ClinicalTrials.gov

For full trial details, please see the original record at https://clinicaltrials.gov/study/NCT07013656




Registration number
NCT07013656
Ethics application status
Date submitted
2/06/2025
Date registered
10/06/2025
Date last updated
10/06/2025

Titles & IDs
Public title
Effects of Combined Administration of Calcium and L-tryptophan on Gut Functions and Blood Glucose in Healthy Humans
Scientific title
Effects of Combined Intraduodenal Administration of Calcium and L-tryptophan on Plasma Glucose, Glucoregulatory Hormones and Gastric Emptying in Response to a Mixed-nutrient Drink in Healthy Adult Males
Secondary ID [1] 0 0
13243
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Healthy 0 0
Condition category
Condition code

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Other interventions - L-tryptophan
Other interventions - Combination of L-tryptophan + Ca-500
Other interventions - Combination of L-tryptophan + Ca-1000
Other interventions - Control

Active comparator: L-tryptophan - In this arm, participants will receive a 75-minute intraduodenal infusion of an isotonic solution containing 1.83 g L-tryptophan, dissolved in 225 mL distilled water. Additionally, 2.2 g of sodium chloride (NaCl) will be added to ensure the solution is isosmotic (\~373 mOsm).

Active comparator: L-tryptophan + Ca-500 - In this arm, participants will receive a 75-minute intraduodenal infusion of an isotonic solution containing 1.83 g L-tryptophan and 1.84 g of calcium chloride dihydrate (CaCl2·2H2O), dissolved in 225 mL of distilled water. Additionally, 1.1 g of NaCl will be added to ensure the solution is isosmotic (\~373 mOsm).

Active comparator: L-tryptophan + Ca-1000 - In this arm, participants will receive a 75-minute intraduodenal infusion of an isotonic solution containing 1.83 g L-tryptophan and 3.68 g of calcium chloride dihydrate (CaCl2·2H2O), dissolved in 225 mL of distilled water. This solution has an osmolality of \~373 mOsm.

Placebo comparator: Control - In this arm, participants will receive a 75-minute intraduodenal infusion of saline (an isotonic solution containing 2.5 g of NaCl, dissolved in 225 mL of distilled water). This solution has an osmolality of \~373 mOsm.


Other interventions: L-tryptophan
L-tryptophan, an aromatic amino acid and one of the building blocks of protein, is a part of our daily diet. The load of L-tryptophan (0.1 kcal/minute) is based on our previous study, in which L-tryptophan represented a submaximal load.

Other interventions: Combination of L-tryptophan + Ca-500
Calcium, an essential mineral and a key component of dairy products, is a regular part of our daily diet. In this condition, both L-tryptophan and calcium will be administered as 'active'. Recent studies have shown that calcium in a dose of 500 mg enhances the effects of L-tryptophan to stimulate gut functions and reduce energy intake. This dose of calcium will be considered 'lower dose'.

Other interventions: Combination of L-tryptophan + Ca-1000
In this condition, both L-tryptophan and calcium will be administered. In our study calcium in a dose of 1000 mg enhances the effects of L-tryptophan to stimulate gut functions and reduce energy intake. This dose of calcium will be considered 'higher dose'.

Other interventions: Control
An isotonic solution containing 2.5 g of NaCl, dissolved in 225 mL of distilled water.
Intervention code [1] 0 0
Other interventions
Comparator / control treatment
Control group

Outcomes
Primary outcome [1] 0 0
Plasma glucose concentrations
Timepoint [1] 0 0
Blood samples will be collected over 4.5 hours: at baseline (time = -30 minutes), then at regular intervals before and after drink administration (times = -25, -15, 0, 10, 20, 30, 45, 60, 75, 90, 120, 180, and 240 minutes).
Secondary outcome [1] 0 0
Gastric emptying
Timepoint [1] 0 0
Breath samples will be collected in sealed tubes over 4.5 hours: at baseline (time = -30 minutes), prior to treatment administration, every 5 minutes after the drink (times = 0 to 60 minutes), and then every 10 minutes until 240 minutes post-drink.
Secondary outcome [2] 0 0
Plasma concentrations of glucoregulatory hormones e.g. glucagon-like peptide (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), C-peptide, glucagon, insulin and cholecystokinin (CCK)
Timepoint [2] 0 0
Blood samples will be collected over 4.5 hours: at baseline (time = -30 minute), then at regular intervals before and after the drink (times = -25, -15, 0, 10, 20, 30, 45, 60, 75, 90, 120, 180, and 240 minutes).
Secondary outcome [3] 0 0
GI symptoms (nausea and bloating) will be assessed as a composite secondary outcome.
Timepoint [3] 0 0
VAS questionnaires will be collected over 4.5 hours: at baseline (time = -30 minutes), at regular intervals before and after the drink (times = -15, 0, 10, 20, 30, 45, 60, 75, and 90 minutes), then every 10 minutes until 240 minutes post-drink.

Eligibility
Key inclusion criteria
Healthy, lean (BMI: 19-25 kg/m2) males will be included in the study. Only men will be included in the study to avoid the confounding effects of the menstrual cycle on gastric emptying. All participants will be required to be weight-stable (i.e. <5% fluctuation) at study entry, which will be ascertained by a stable body weight in the preceding 3 months.
Minimum age
18 Years
Maximum age
70 Years
Sex
Males
Can healthy volunteers participate?
Yes
Key exclusion criteria
* Significant GI symptoms, or history of GI disease or surgery
* Current gallbladder or pancreatic disease
* Cardiovascular or respiratory diseases
* Any other illnesses as assessed by the investigator (including chronic illnesses not explicitly listed above)
* Use of prescribed or non-prescribed medications (including vitamins and herbal supplements) which may affect energy metabolism, GI function, body weight or appetite (e.g. domperidone, cisapride, anticholinergic drugs (e.g. atropine), metoclopramide, erythromycin, hyoscine, orlistat, green tea extracts, Astragalus, St Johns Wort etc.)
* Lactose intolerance/other food allergy(ies)
* Individuals with low ferritin levels (<30 ng/mL), or who have donated blood in the 12 weeks prior to taking part in the study
* High performance athletes
* Current intake of > 2 standard drinks on > 5 days per week (>140g/week)
* Current smokers of tobacco (cigarettes, cigars, pipes, sheesha, chewing, vaping etc.)
* Current use of recreational drugs, e.g. marijuana
* Current intake of any illicit substance
* Vegetarians
* Inability to tolerate nasoduodenal tube
* Inability to comprehend study protocol
* Restrained eaters (score >12 on the 3-factor eating questionnaire)

Study design
Purpose of the study
Other
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s

The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Crossover
Other design features
Phase
Not applicable
Type of endpoint/s
Statistical methods / analysis

Recruitment
Recruitment status
Not yet recruiting
Data analysis
Reason for early stopping/withdrawal
Other reasons
Date of first participant enrolment
Anticipated
28/06/2025
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
25/11/2026
Actual
Sample size
Target
16
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
SA
Recruitment hospital [1] 0 0
Clinical Research Facility, Adelaide Health and Medical Sciences Building - Adelaide
Recruitment postcode(s) [1] 0 0
5005 - Adelaide

Funding & Sponsors
Primary sponsor type
Other
Name
University of Adelaide
Address
Country

Ethics approval
Ethics application status

Summary
Brief summary
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 0 0
Prof Christine Feinle-Bisset
Address 0 0
Adelaide Medical School University of Adelaide Level 5 Adelaide Health and Medical Sciences Building, Cnr George St and North Tce, Adelaide, SA 5005
Country 0 0
Phone 0 0
Fax 0 0
Email 0 0
Contact person for public queries
Name 0 0
Prof Christine Feinle-Bisset
Address 0 0
Country 0 0
Phone 0 0
+61 8 8313 6053
Fax 0 0
Email 0 0
[email protected]
Contact person for scientific queries

Data sharing statement


What supporting documents are/will be available?

No Supporting Document Provided


Results publications and other study-related documents

No documents have been uploaded by study researchers.

Results not provided in https://clinicaltrials.gov/study/NCT07013656