Human milk protein vs. formula protein and their use in preterm infants

We review the current available evidence on the metabolic fate of human milk proteins and their potential clinical implications for growth and body composition development vs. those of formula proteins in preterm infants.

The decreased content of human milk protein in preterm mothers throughout lactation might contribute to the reduced growth reported in exclusively human milk-fed infants compared with that of formula-fed infants. Recent studies have demonstrated that preterm infants are capable of degrading human milk proteins regardless of their degree of prematurity or postnatal age, with limited contribution from milk proteases to protein digestion. The nitrogen balance of fortified human milk-fed preterm infants is higher than that of formula-fed preterm infants. Moreover, the growth of human milk-fed preterm infants appears to be accompanied by fat-free mass deposition.

Provided that adequate protein and energy intakes are delivered, human milk enhances protein use rather than oxidation as well as promotes tissue growth, leading to preferential fat-free mass deposition and contributing to the recovery of the body composition in preterm infants. Human milk feeding should be supported and promoted for all preterm mother-infant pairs.