Micronutrients, the gut microbiota, and infection susceptibility in infants.

Micronutrient deficiencies are common during infancy, particularly in settings with a high burden of infectious diseases. At the same time, the developing infant gut microbiota is a key determinant of susceptibility to infection from both resident pathobionts and incoming enteric pathogens. Recent human and experimental studies suggest that micronutrients regulate this developing microbial ecosystem in a highly context-dependent manner, with effects varying according to developmental stage, nutritional status, intestinal location, and environmental exposure. In this review, we synthesise current evidence linking micronutrient-microbiota interactions to microbial competition and metabolism, epithelial barrier integrity, and mucosal immunity, and discuss how these interactions may shape susceptibility to enteric and invasive bacterial infections during infancy.