Impact of mother's own milk vs. donor human milk on gut microbiota colonization in preterm infants: a systematic review

Background: Nutritional intake in preterm infants is associated with short- and long-term outcomes. The favorable outcomes of preterm infants who predominantly receive their mother's own milk (MOM) are thought to be mediated partly through beneficial effects on the gut microbiome. When MOM is not available, donor human milk (DHM) is recommended as the best alternative. However, DHM is less effective in preventing adverse outcomes, which may be explained by compositional differences between MOM and DHM, resulting in different microbiome development. This systematic review focuses on the effects of predominant DHM vs. MOM feeding on the gut microbiota composition in preterm infants. Methods: A comprehensive search was conducted across MEDLINE, Embase, and Cochrane databases. Eight out of the 717 publications identified were included. Data on gut microbiota composition, alpha diversity, and taxonomic differences between DHM- and MOM-fed preterm infants were extracted and analyzed. Results: The microbiome composition was distinct between the two feeding groups. Alpha diversity measures were lower in DHM-fed infants, particularly when preterm formula (PF) was also provided. DHM-fed infants showed higher abundances of Staphylococcaceae and Clostridiaceae, and lower abundances of Bacteroidetes and Bifidobacterium. Conclusion: The observed gut microbiome differences in DHM-fed preterm infants have previously been linked to adverse health outcomes. This underlines the importance of increasing the awareness of MOM intake in preterm infants. Further studies should explore the mechanisms through which human milk affects health outcomes.