This systematic review aimed to synthesise the results from studies investigating the effects of prebiotics and probiotics on kynurenine pathway metabolism. Thirteen studies were identified for inclusion, comprising 12 probiotic and two prebiotic arms. Participants included healthy individuals and individuals with various clinical conditions. Twelve metabolites were examined across the studies, using a range of biological samples. Across all interventions, 11 reported an effect on ≤ metabolite. Although limited by clinical and methodological heterogeneity, pooled analysis (n = 253) found probiotics to significantly affect serum kynurenine (g = 0.315, CI = 0.070 to 0.560, p = 0.012, 4 studies, I² = 0%) and the kynurenine:tryptophan ratio (g = 0.442, CI = 0.074 to 0.810, p = 0.018, 4 studies, I² = 42 %). Risk of bias across the studies was generally low. The results provide preliminary evidence that probiotics can modulate kynurenine pathway metabolism, with less evidence available regarding prebiotics. Future studies which further consider methodological confounds and sample characteristics are required, to establish intervention efficacy. PROSPERO registration #CRD42019154677.

Item Type:	Refereed Article
Keywords:	kynurenine, tryptophan, gut-brain axis, prebiotic, probiotic, nutraceutical, systematic review, mental health, psychiatry, neuroscience
Research Division:	Biomedical and Clinical Sciences
Research Group:	Medical biochemistry and metabolomics
Research Field:	Medical biochemistry - amino acids and metabolites
Objective Division:	Health
Objective Group:	Clinical health
Objective Field:	Prevention of human diseases and conditions
UTAS Author:	Purton, T (Miss Terry Purton)
UTAS Author:	Honan, C (Dr Cynthia Honan)
ID Code:	142572
Year Published:	2021
Web of Science® Times Cited:	23
Deposited By:	UTAS Centre for Rural Health
Deposited On:	2021-01-27
Last Modified:	2022-08-25
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