Modulation of Animal Gut Health by Milk Oligosaccharide

Milk oligosaccharides (MOs) are an abundant, diverse, and complex class of carbohydrates found in breast milk that are increasingly recognized as key determinants of intestinal health during early life. Their composition and structural diversity differ markedly across mammalian species, shaping host–microbe interactions and contributing to intestinal barrier homeostasis. This review systematically summarizes the compositional and structural variations of MOs across mammals and discusses their regulatory roles in intestinal homeostasis within a structure‐based classification framework. These roles are mediated through their coordinated effects on gut microbiota composition and function, the intestinal epithelial barrier, and immune function. By integrating these dimensions, this review outlines a conceptual framework for MO‐host interactions and highlights the potential of MO‐derived nutritional strategies to support mammalian intestinal health in early life.