The ketogenic diet affects metabotype. (a) Partial least squares discriminant analysis (PLS-DA) of metabolomics pofiles. (b) Heatmap of discriminant metabolites with Variable importance of projection >1. (c) Pathway analysis of discriminant metabolites. Pathways with impact > 0.1 and p < 0.05 are highlighted. (d) The ratio of kynurenine to tryptophan (IDO1 indicator) and kynurenic acid to kynurenine (KAT indicator). (e) Summary of alterations in tryptophan metabolism after ketogenic diet treatment. n = 6, 4, 9, 7 for NDS, KDS, NDL, and KDL, respectively. Data are presentd as mean±SEM (d). One-way ANOVA followed by Turkey's post-hoc test (d): *p < 0.05. IDO1, indoleamine 2, 3-dioxygenase 1; ND, normal diet; KAT, kynurenine aminotransferase; KD, ketogenic diet; KYN, kynurenine; KA, kynurenic acid; PLP, pyridoxal phosphate; TRP, tryptophan.