Early Iron Exposure on the Gut Microbiota in Young Infants

Disturbance of the gut microbial colonization during infancy may result in long-term programming impact of metabolism and disease risks of the host. The early gut microbial colonization coincides with the maturation of the infant's mucosal innate immune system and research showed that the gut microbial dysbiosis is associated with impaired innate immune development. Thus, ensuring proper microbial colonization early in life is critical to the maturation of the immune system and long-term health. Iron fortification can increase the abundance of pathogenic bacteria and induce inflammation in older infants. However, it is still not known what the effect of iron is on a more vulnerable population: the newborn infant, who has immature immune system. Infants 0-4 months are at a low risk for iron deficiency due to the iron endowment at birth, which is compatible with the very low iron content (\<0.5mg Fe/L) in breastmilk. However, commercial infant formulas are all fortified with ≥12mg Fe/L. Whether this striking difference drives adverse health effects is unknown/unexamined, especially on early colonization and immune homeostasis. The overall objective is to determine the impact of high vs. low iron exposure in formula-fed infants during the early post-natal months on gut microbiome.