Bioactive components in preterm and term human milk compared to donor human milk: A pilot study

Mother's own milk (MOM) is considered the optimal nutriton for preterm infants. When MOM is insufficient, donor human milk (DHM) is the preferred alternative for very preterm infants, but processing is known to affect the composition of the bioactive components. This pilot study aimed to describe the analytical methods and investigate levels of bioactive components in preterm and term MOM according to lactation stages and compare with DHM: 1) total MFGM and MFGM protein levels, 2) proteins related to MFGM and EV: BA46, CD81 and xanthine oxidase (XOD) levels and 3) lipid content and composition.

Colostrum, transitional and mature milks were collected from healthy mothers, who gave birth to either term (n = 10) or very preterm (n = 10) infants, at day 0-4, 7-14 and 28-45 after delivery, respectively. Thirteen pooled DHM samples were also included. MFGM quantification, Western blotting and lipidomics were used for analysis. Preterm samples were compared with term samples according to lactation stage and all MOM samples were compared with DHM.

MFGM level was significantly lower in preterm colostrum compared with term colostrum (15.5 ± 1.1 vs. 18.1 ± 4.2, p-value = 0.02). No differences between preterm and term milk were found in later lactation stages (all p-value >0.05). DHM had significantly lower levels of MFGM compared with preterm and term MOM (p-value <0.05). BA46, CD81 and XOD levels did not differ between preterm and term milk at any lactation stage (all p-value >0.05). Preterm and term milk contained higher amounts of BA46, CD81 and XOD compared to DHM. There were no major differences in lipid class composition of preterm and term milk. To highlight, preterm milk contained significantly higher amounts of sphingomyelin compared to DHM at all lactation stages (all p-value <0.05), whereas term milk did not differ significantly from DHM (all p-value >0.05).

With these preliminary results we conclude that preterm and term MOM were largely comparable in MFGM, associated proteins and lipid composition across lactation stages. In contrast, DHM contained lower levels of MFGM and associated proteins, explaining its lower bioactive potential for very preterm infants.