Pertubation of metbaolites on tryptophan pathway regarding BMI and HDP status. Metabolites in the tryptophan pathway (A) were first annotated by the Mummichog algorism in Metabanalyst via the empirical compound library, and then verified by matching against the in-house physical standard library (OL1-OL2b) and public database (PDa-PDd). OL1, matching with In-house physical standard library (IPSL) via retention time (RT), exact mass (MS), and tandem mass similarity (MS/MS); OL2a, matching with IPSL via MS and RT; and OL2b, the annotation for the isomer or derivatives of the compound, based on matching with IPSL via MS and MS/MS. PDa, annotation based on public database via MS and experimental MS/MS (could be the listed compound, or the isomer or derivatives of the listed compound); PDc, annotation based on public database via exact mass and isotopic similarity. #metabolite determined to associate with BMI in the non-HDP and/or HDP group (Supplementary Table S1); ## metabolite determined to associate with HDP in at least one of the BMI categories (Supplementary Table S2); ### metabolite determined to associate with HDP and BMI by regression modeling (Table 3). The box plots (B) of the identified/annotated metabolites were based on the relative peak intensity of the corresponding signal (RT_exact mass) and the classification with BMI categories (NW, normal weight; OW, overweight; OB, obese) and the HDP status (blue: with-HDP; orange: without HDP). The pairwise comparison was conducted by student t-test or Wilcoxon Rank-Sum Test (if the sample size in one of the group is <10). Pairwise comparisons: (a) HDP vs. without-HDP in NW; (b) with-HDP vs. without-HDP in OW; (c), with-HDP vs. without-HDP in OB; (d) OW vs. NW in with-HDP; (e) OB vs. NW in with-HDP; (f) OW vs. NW in without-HDP; (G) OB vs. NW in without-HDP. Comparisons with significant changes were labled in the box plots (*p < 0.05, **p < 0.01, ***p < 0.001). (B) only presented the box plots for metabolites for serotonin, acetyl serotonin, and 5-methoxyindoleacetate. Box plots for other metabolites were shown in Supplementary Figure S1.