NCT03059862

The Role of Dietary Tryptophan on Aryl Hydrocarbon Receptor Activation

The Role of Tryptophan on Aryl Hydrocarbon Receptor Activation: a Randomized, Double Blind, Placebo-controlled, Crossover Design Pilot Trial

• Status: Completed
• Phase: N/A
• Study type: Interventional
• Enrollment: 20 (actual)
• Sponsor: McMaster University · Academic / Other
• Sex: All
• Age: 18 Years – 75 Years
• Healthy volunteers: Accepted

Summary

This study evaluates the role of dietary L-tryptophan, an essential amino acid, in the activation of a specific cellular component: the aryl hydrocarbon receptor.

Detailed description

The Aryl hydrocarbon receptor (AHR) is a ligand-dependent transcription factor implicated in a range of key cellular events. In the gut, AHR is crucial for maintaining intestinal barrier immune homeostasis. The physiology of the AHR, however, is not completely understood; its precise gut luminal activators and functional consequences are unknown. Some AHR ligands originate from the diet. Commensals play crucial roles in metabolizing tryptophan and other amino acids such as tyrosine, with the subsequent production of tryptophan metabolites. Previous studies show that inflammatory bowel disease (IBD) patients have impaired production of AHR agonists by the microbiota. Furthermore, dietary supplementation with tryptophan ameliorates clinical parameters of colitis in rodent models. Whether these findings translate into human pathophysiology has not been explored. In the present study, the investigators will evaluate the effect of high- versus low-tryptophan diet on AHR activation in healthy participants. Briefly, participants will be instructed to follow a standardized low-tryptophan diet and will be randomized to a 3-week L-tryptophan supplement or placebo. Later, after a 2-week washout period, participants will crossover to the other arm. In addition, the effect of tryptophan and microbiota-derived metabolites on AHR activation will be analyzed.

Conditions

• Diet Modification

Interventions

Type	Name	Description
DIETARY_SUPPLEMENT	L-tryptophan	3 g/day of L-tryptophan added to the standardized low-tryptophan diet. Duration: 3 weeks.
DIETARY_SUPPLEMENT	Placebo	A placebo will be added to the standardized low-tryptophan diet. Duration: 3 weeks.

Timeline

• Start date: 2017-11-01
• Primary completion: 2018-04-30
• Completion: 2018-06-30
• First posted: 2017-02-23
• Last updated: 2023-04-13

Locations

1 site across 1 country: Canada