Serum Immune System Biomarkers Neopterin and Interleukin-10 Are Strongly Related to Tryptophan Metabolism in Healthy Young Adults.

Background: Changes in tryptophan metabolism through the vitamin B-6-dependent kynurenine pathway have been linked to activation of the immune system.

Objective: We hypothesized that blood concentrations of tryptophan and its catabolites were associated with biomarkers relevant to inflammatory processes in healthy noninflamed subjects.

Methods: Healthy young adults (n = 737) aged 18-28 y without any known diseases or clinical evidence of inflammation provided blood samples for analysis of serum tryptophan/kynurenine metabolites, neopterin, C-reactive protein (CRP), and plasma pyridoxal 5'-phosphate (PLP) with LC-tandem mass spectrometry methodologies.

Tryptophan catabolism and vitamin B-6 status are affected by gender and lifestyle factors in healthy young adults.

Background: Abnormalities of tryptophan (Trp) metabolism through the kynurenine (Kyn) pathway have been reported in various diseases; however, nutritional and lifestyle factors that affect this pathway in healthy individuals are not well documented.

Objective: Our aim was to examine the effect of vitamin B-6 status and lifestyle factors including the use of vitamin B-6 supplements, alcohol, smoking, and oral contraceptives on Trp and its Kyn metabolites in a cohort of 2436 healthy young adults aged 18-28 y.

Methods: Anthropometric and lifestyle data were collected by questionnaire.