Carbohydrate polymersSep 14, 2025

Varied structures and types of human milk sugars and their possible benefits for brain development

Gut-Brain Axis Weekly Brief ↗PubMed ↗DOI ↗

Updated Jan 20, 2026

Abstract

Human milk oligosaccharides (HMOs) encompass over 200 distinct molecules that are crucial for neonatal development.

HMOs are classified into neutral fucosylated, neutral non-fucosylated, and acidic sialylated types based on their sugar composition.
Compositional variation of HMOs is influenced by genetic factors, mode of delivery, geographical and environmental differences, and maternal health status.
HMOs may impact neurodevelopment through interactions with the gut microbiota, promoting beneficial bacteria and enhancing intestinal barrier integrity.
They could also influence neurotransmitter pathways and the release of factors that support neuronal growth and synaptic connections.
Safety assessments indicate that HMOs are suitable for inclusion in infant formula, potentially addressing nutritional gaps for infants not fully breastfed.

Simplified

Human milk oligosaccharides (HMOs) are the third most abundant solid component in human milk, following lactose and fat, and play a crucial role in neonatal development through multiple mechanisms. This review elaborates on the structural diversity of HMOs, encompassing over 200 distinct molecules. These molecules are classified into neutral fucosylated, neutral non-fucosylated, and acidic sialylated types based on their monosaccharide composition and terminal modifications. Furthermore, factors influencing the compositional variation of HMOs are explored, including genetic factors, mode of delivery, geographical and environmental differences, as well as maternal health status. Critically, HMOs can exert a profound impact on neurodevelopment via the "gut-brain axis". HMOs can modulate the gut microbiota, promoting the proliferation of bifidobacteria, thereby enhancing the integrity of the intestinal barrier and reducing the risk of pathogen invasion, which indirectly protects brain health. Additionally, they directly influence neurotransmitter pathways and the release of neurotrophic factors, facilitating neuronal growth and synaptic plasticity, and thus promoting brain development. Safety assessments confirm that HMOs are suitable for inclusion in infant formula, offering a promising avenue to bridge nutritional gaps in infants when breastfeeding is insufficient.