Effects of Combined Administration of Calcium and L-tryptophan on Gut Functions and Blood Glucose in Healthy Humans

Summary

The intervention in this study consists of 75-minute intraduodenal infusions of isosmotic solutions containing either saline (control), L-tryptophan, or calcium combined with L-tryptophan. Participants enrolled into the study will receive, in a randomised, double-blind fashion either (i) saline (control), (ii) L-tryptophan at a rate of 0.1 kcal/minute, (iii) combination of L-tryptophan (0.1 kcal/minute) + 500 mg calcium, or (iv) combination of L-tryptophan (0.1 kcal/minute) + 1000 mg calcium in four separate sessions, each of which will be separated by at least 4 (and up to 10) days. Each study session will be 4-6 hours. Studies will be carried out in the Clinical Research Facility of the Adelaide Medical School, the University of Adelaide, by staff and students trained in the required techniques.

Conditions

• Healthy

Interventions

OTHER

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

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

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

Control

An isotonic solution containing 2.5 g of NaCl, dissolved in 225 mL of distilled water.

Sponsors & Collaborators

• University of Adelaide

  lead OTHER

Principal Investigators

• Prof Christine Feinle-Bisset · Adelaide Medical School University of Adelaide Level 5 Adelaide Health and Medical Sciences Building, Cnr George St and North Tce, Adelaide, SA 5005

Study Design

Allocation

RANDOMIZED

Purpose

OTHER

Masking

TRIPLE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Max Age

70 Years

Sex

MALE

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2025-06-28

Primary Completion

2026-06-28

Completion

2026-11-25

Countries

• Australia

Study Locations