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In Pursuit of Total Exposure Health
Published in Kirk A. Phillips, Dirk P. Yamamoto, LeeAnn Racz, Total Exposure Health, 2020
There are two major transitions which occur sometime after delivery that accompany the establishment of stable gut microbiota, with the first occurring soon after birth during lactation and the second during the weaning period with the introduction of solid foods along with continued nursing (Robertson et al. 2018). The first transition creates a gut microbiome abundant with genes specific for the infant’s digestion of milk proteins. A mother’s breastmilk, which contains bacteria and prebiotic human milk oligosaccharides (HMOs), introduces new microbial communities and stimulates the maturation of the neonatal gut microbiome. In contrast, feeding an infant with formula has been found to impair the development of the neonatal immune system and alter metabolism. Breastfed babies tend to have a stable and relatively uniform gut microbiome when compared to babies fed via formula, even when only small amounts of formula are ingested. Evidence suggests that in addition to delivery via C-section and formula feeding, the use of prenatal antibiotics is another action that can compromise the microbial colonization of the newborn gut. It is suggested that these three actions be practiced prudently and followed by measures to restore the natural composition of the microbiome (Mueller et al. 2015).
Developing infant gut microflora and complementary nutrition
Published in Journal of the Royal Society of New Zealand, 2020
Caroline C. Kim, Shanthi G. Parkar, Pramod K. Gopal
The composition of breast milk also plays an important role in facilitating the selection of early colonisers, particularly the human milk oligosaccharides (HMOs). More than 200 structurally diverse unconjugated 3–15 carbon unit long oligosaccharides consisting of the monosaccharides glucose, galactose, N-acetylglucosamine (GlcNAc), fucose, and N-acetylneuramic acid (sialic acid) are present in human breast milk (Ayechu-Muruzabal et al. 2018). Bifidobacterial genomes, especially Bifidobacterium longum subsp. infantis, show a high degree of specialisation for utilising HMOs (Underwood et al. 2015), often encoding gene clusters consisting of numerous Carbohydrate-Active enZymes (CAZymes), ABC transporters, and solute-binding proteins that specifically target oligosaccharides derived from HMOs (Thomson et al. 2018), thus enabling B. longum subsp. infantis to competitively colonise the gut of breast-fed infants. One of the reasons that many commercial infant formulae are supplemented with non-digestible oligosaccharides such as galacto-oligosaccharides and fructo-oligosaccharides is to partially mimic the prebiotic properties of human breast milk. Although the dominance of bifidobacteria in the infant gut is often considered an indication of normal gut maturation, not all infants seem to reach this developmental milestone. In some studies, high abundances of Proteobacteria and Firmicutes, and very low numbers of Actinobacteria – regardless of the birth modes – have been reported in healthy neonates and infants from China and Brazil (Kuang et al. 2016). Similarly in other studies, Bacteroides rather than bifidobacteria were reported to be the dominant group of bacteria in breast-fed babies (Tannock et al. 2016; de Muinck and Trosvik 2018). It is known that certain Bacteroides can degrade HMOs via mucin utilisation pathways (Marcobal et al. 2011), which may explain this observation.