Early Life Microbiome Colonization and Human Health

Abstract

The early life assemblages of microbial community membership, diversity, and function within the gastrointestinal tract play fundamental roles in shaping host growth, body composition, and organ development and function, including the programming of immune systems, shaping central nervous system signaling and behaviour, and influencing metabolic set points. Abnormal colonization during this period may elevate the risk of chronic and metabolic disease throughout the lifespan. Research on the influence of microbial communities on neonatal health has historically been focused on the prevention and treatment of infectious disease during the neonatal and early adolescent period. Over the last decade, deeper insights into the role of normal human microbiome colonization in early life and childhood has grown substantially and strong evidence for its importance in human development has accumulated. Acquisition of an early life microbiome is influenced by the route of birth, nutrition composition and source, antibiotic and toxin exposures, geological location and home environment, and other pivotal factors. The microbiome appears to be dynamically developed during the first year of life but becomes more stabilized once community diversity and membership increases, along with compensatory and complementary host immune response. During microbial community assemblage, it is proposed that critical developmental immune windows are shaped that influence host homeostasis and disease risk in later life. This chapter will review this rapidly developing field and highlight the role of the microbiome in early life along with implications for long-term health during the lifespan.