Figure 3.

Influence of diet introduction and food composition on the infant microbiota diversity. The introduction of feeding is a milestone in the development of adaptive immunity, the production of digestive enzymes and the transformation of the consumed milk into “living integrated food” (chyme). The diet is essential in the colonization processes during the early neonatal period, as well as in the establishment of a “lifelong” microbiota composition. The microbiome of breastfed infants consists predominantly of Bifidobacterium (B. breve, B. longum, and B. bifidum) and Lactobacillus (64). The utilization of HMOs from human milk by Bifidobacteria is especially beneficial for the production catabolites (Acetate Lactate Formate 1,2-Propanediol) and AAA-derived Co-HMO metabolism products (65). Formula-fed infants have a more diverse microbiota, with increased abundance of Bacteroidetes, Firmicutes, Clostridium difficile, and Enterobacteriaceae and in turn BCAA and AAA catabolites (64, 65). Complementary feeding increases gut microbial diversity with dominance of Lachnospiraceae, Ruminococcaceae, Bacteroidaceae, and Prevotellaceae species and production of BCFAs and SCFAs (65, 66). Human milk oligosaccharide (HMO), aromatic amino acid (AAA), branched chain amino acid (BCAA), indolelactate (ILA), phenyllactate (PLA), 4-hydroxypheyllactate (4-OH-PLA), branched chain fatty acids (BCFAs), and short-chain fatty acids (SCFAs).