Fig. 3

Metabolites derived from microbial fermentation of phenylalanine and pectins were increased in the synbiotic group. a Box plots presenting the antimicrobial metabolite d-3-phenyllactic acid (PLA), which is derived from the microbial fermentation of phenylalanine in the prebiotic (blue) compared with the synbiotic (orange) group, using a mixed-effects model, p < 0.001 for time and p = 0.04 for interaction. b Box plots presenting the galacturonic acid, which is derived following microbial degradation of pectins. Galacturonic acid was increased in the synbiotic group (orange) at age 6 months (Mann–Whitney U test, p = 0.039). Data are presented as mean ± SD. Prebiotic group (n = 23 at 1 and 4 months, n = 27 at 6 months, and n = 26 at 12 months). Synbiotic group (n = 22 at 1 month, n = 25 at 4 months, n = 20 at 6 months, and n = 27 at 12 months). RC-relative concentration