Individualized Reconstitution of Human Milk Microbiota: A Feasible Approach in Real-World Settings

Mother's own milk (MOM) is the most complete nutritional resource for newborns. In cases where mothers are unable to produce sufficient milk or cannot breastfeed, the preferred alternative is pasteurized donor human milk (PDM), which is routinely provided by human milk banks. PDM offers a superior range of nutritional and immunological elements compared to any commercially available formula. However, to ensure biosafety, PDM undergoes pasteurization, a process that inactivates commensal microbiota and reduces certain bioactive compounds. This study presents a protocol designed to restore the microbiota of PDM using MOM as a microbial source, adapting the approach to a real-world clinical setting. The protocol was implemented in a clinical trial conducted at a maternity hospital and its associated human milk bank, with the aim of providing personalized donor milk to preterm infants whose mothers cannot produce sufficient milk. The methodology involves inoculating PDM with 10% of MOM, followed by incubation at 37 °C for 4 h. Microbiological analysis demonstrated successful bacterial growth in the inoculated milk (IM) post incubation, with the microbiota profile of the reconstituted milk (RM) closely resembling that of MOM, indicating effective microbiota restoration. These results suggest that the reconstitution protocol is feasible for implementation in neonatal care, with the potential to enhance the nutritional and immunological quality of PDM, thereby supporting the health and development of non-breastfed newborns.