Building a Beneficial Microbiome from Birth

Abstract

The microbiota has recently been recognized as a driver of health that affects the immune, nervous, and metabolic systems. This influence is partially exerted through the metabolites produced, which may be relevant for optimal infant development and health. The gut microbiota begins developing early in life, and this initial colonization is remarkably important because it may influence long-term microbiota composition and activity. Considering that the microbiome may play a key role in health and disease, maintaining a protective microbiota could be critical in preventing dysbiosis-related diseases such as allergies, autoimmunity disorders, and metabolic syndrome. Breast milk and milk glycans in particular are thought to play a major role in shaping the early-life microbiota and promoting its development, thus affecting health. This review describes some of the effects the microbiota has on the host and discusses the role microbial metabolites play in shaping newborn health and development. We describe the gut microbiota structure and function during early life and the factors that determine its composition and hypothesize about the effects of human milk oligosaccharides and other prebiotic fibers on the neonatal microbiota.

Keywords: human milk oligosaccharides; microbial metabolites; microbiota; prebiotics; short-chain fatty acids.

FIGURE 1

Interactions between the gut microbiota and host physiology. The gut microbiota exerts an effect on several aspects of host physiology through the 2 depicted axes. Thus, the microbiota is able to influence metabolism and brain functions and acts locally by modulating intestinal function (2, 3, 7). CNS, central nervous system.

FIGURE 2

Evolution of the early-life gut microbiota and events influencing its composition. Factors such as the maternal microbiota, delivery mode, gestation time, and type of feeding strongly influence the microbiota. Colonization and expansion of the gut microbiota, shaped by diet, results in the establishment of an adult-like microbiota around 2–3 y of age, with firmicutes and bacteroidetes as the predominant phyla. Early life is a susceptible period when modifications in the gut microbiota composition can have long-term effects on health (5, 22).

FIGURE 3

Selected HMO structures. HMOs are composed of 5 monosaccharides. Lactose can be fucosylated or sialylated to generate the following trisaccharides: the fucosyllactoses 2′-FL and 3-FL and the sialyllactoses 3′-SL and 6′-SL. It can be further elongated to generate tetrasaccharides, e.g., LNT and LNnT. Chains can be further elongated, fucosylated, and/or sialylated to generate more complex structures. FL, fucosyllactose; Fuc, fucose; Gal, galactose; Glc, glucose; GlcNAc, N-acetylglucosamine; HMO, human milk oligosaccharide; LNnT, lacto-N-neotetraose; LNT, lacto-N-tetraose; Neu5Ac, N-acetylneuraminic acid; SL, sialyllactose.