A8 DIETARY TRYPTOPHAN MODULATES KYNURENINE AND INDOLE PRODUCTION IN HEALTHY INDIVIDUALS

Abstract Background Tryptophan is an essential amino acid that transformed by host and gut microbial enzymes into multiple bioactive metabolites regulate immunity, mood circadian rhythms. In particular, indoles, produced bacterial metabolism of tryptophan, have recently gained central attention. Indoles are activators the aryl hydrocarbon receptor (AhR), which crucial for maintenance intestinal homeostasis immunity. supplementation in fortified foods been advocated to prevent chronic inflammatory conditions, from autism inflammation. However, whether dietary tryptophan affects immune function, metabolic pathways gastrointestinal symptoms healthy subjects, unknown. Aims To assess supplementation, subjects on a low diet, induces changes microbiota-derived (indoles), cytokine production or symptoms. Methods We performed randomized, double blind, placebo-controlled, crossover study 20 individuals, between 18 75 years old, following regular diet. Subjects were instructed start standardized diet randomly assigned 3-week supplement (3gr/day) placebo. After 2-week washout period, crossed over opposite intervention arm. Self-administered questionnaires (GSRS, DASS21 HADS) used mood/anxiety/stress. Stool, urine blood samples collected measure (kynurenine pathway indoles) cytokines. Results Supplementation was well tolerated no mood/anxiety found. Compared with placebo, increased urinary plasma levels indoleamine 2,3-dioxygenase (p= 0.002 p= 0.02, respectively), key enzyme kynurenine pathway, several indoles 0.0008 0.01, suggestive activation pathways. there measurable production. There positive correlation fecal anxiety depression scores, suggesting may impact behavior humans. Conclusions Dietary individuals safe had effect metabolism, mainly indole pathways, known immunomodulatory properties. Although effects found, further studies warranted investigate disorders altered AhR such as bowel disease, syndrome celiac disease. Funding Agencies None