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

Launched by UNIVERSITY OF ADELAIDE · Jun 2, 2025

Keywords

ClinConnect Summary

This clinical trial is looking at how two substances, calcium and L-tryptophan, affect gut function and blood sugar levels in healthy men. The study will give participants different solutions through a tube placed in the stomach for 75 minutes. Some will receive a saltwater solution (the control), while others will receive L-tryptophan alone or in combination with either 500 mg or 1000 mg of calcium. The study will take place over four sessions, separated by at least four days, each lasting 4-6 hours.

To participate, men aged between 18 and 65 who are healthy and have a body mass index (BMI) between 19 and 25 are eligible. However, those with certain health issues, like gastrointestinal diseases, heart or lung problems, or who take medications that affect metabolism, cannot join. Participants should be stable in their weight and not involved in any high-performance sports or smoking. Overall, this trial aims to better understand how these substances might influence gut health and blood sugar, which could be important for future dietary recommendations.

Gender

MALE

Eligibility criteria

• Inclusion Criteria:
• • Healthy, lean males (only men will be included in the study to avoid the confounding effects of the menstrual cycle on gastric emptying).
• • BMI: 19-25 kg/m2,
• • Weight-stable (i.e. \<5% fluctuation) at study entry, which will be ascertained by a stable body weight in the preceding 3 months.
• 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)