Summary

The trajectory of the gut microbiota changes with contrasting health-associated consequences for the host during infancy and old age. In this respect, a diverse and complex microbial ecosystem develops after birth, which undoubtedly has a profound influence on health into later life. Factors reported to influence the development of the infant gut microbiome include delivery mode, gestational age, host genetics, feeding regime and perinatal antibiotic usage. The microbiota of full-term vaginally born, exclusively breast fed infants, with no previous exposure to antibiotics can be considered the “gold standard” in early life. We have shown that the mode of delivery and gestational age at birth both have significant effects on microbiota development in early life. Perturbations of optimum microbiota development, as a result of C-section and preterm delivery combined with antibiotic exposure have likely long-term implications for microbial diversity and immune-related health. Breast milk is the optimum first food for microbiome evolution, and is influenced by lactation stage as the primary driving factor in microbiota compositional changes over lactation from birth to 6 months, while mode of delivery was not a factor driving compositional changes throughout human lactation. The late-life gut microbiota is influenced by physiological changes within the host, illness, diet and lifestyle that impact on its composition and functionality. Reduced microbial diversity, loss of beneficial microorganisms and increased pathobionts are key signatures associated with late aging. Such changes have been associated with degenerative diseases including inflammageing, Alzheimer’s disease, Parkinson’s disease, and increased risk of infection with Clostridioides difficile. This presentation will examine early- and late-life factors that contribute to contrasting gut microbiota disturbances and the consequences associated with these disruptions. Evidence of nutritional and probiotic/prebiotic interventions may help alleviate the effects of gut microbiota changes into old age.