FIG. 3.

(A)Subnetwork of the derived metabolic network (estimated by Gaussian graphical modeling) emphasizing caffeine and related compounds. On each node, the results from linear regression analysis for 3,5-T2 concentration either as categorical (effect compared with the lowest group, that is, <0.20 nM; dark gray: 0.20–0.33 nM and light gray: >0.33 nM) or continuous variable (*considering participants with [3,5-T2] >0.20 nM; black) as portion of the association strength are given as −log10 (FDR-value). Significant results in at least one of these with an FDR value below 5% are depicted as pie charts. Node sizes are inversely proportional to the lowest FDR-value. The prefixes P and U denote plasma and urine metabolites, respectively. Edges represent significant partial correlations (par. cor.) between metabolites. (B) Boxplots of plasma (blank) or urine (gray) levels of caffeine and paraxanthine across groups of [3,5-T2]. Diamonds indicate mean levels.