Infant Feeding Practices and the Intestinal Microbiome in the First Year of Life

A healthy intestinal microbiome is critical for lifelong health; however, recent studies have reported a dysfunctional intestinal microbiome in breastfed infants. Probiotics have been used in an attempt to restore the intestinal microbiome, but colonization has been transient, inconsistent among individuals, or has not positively impacted the host’s gut. Additionally, studies have shown that dietary interventions can alter the intestinal microbiome in animal models and adults; these changes have not been observed in infants. The weaning period provides a unique opportunity to observe how specific food change the intestinal microbiome composition and microbial metabolism and allows us to investigate specific microbe-food interactions that would not be possible in adults with a diverse diet. We found that in breastfed, term, newborn-infants, probiotic supplementation with B. infantis within the first month postnatal, in combination with breast milk, resulted in stable colonization that persisted until at least 1 year postnatal. In healthy breastfed infants 2-4 months old, probiotic supplementation with B. infantis for 28 days resulted in stable colonization that persisted until at least one-month post-supplementation. Lastly, the introduction of different solid foods, pear and sweet potato, to 6–8-month-old, breastfed infants led to changes in microbial metabolism as evidenced by changes in fecal organic acid and glycan content. Thus, probiotic and dietary interventions in the first year of life are able to change both intestinal microbial community structure but also metabolic function which may have implications for long-term health