Variability in human milk composition: benefit of individualized fortification in very-low-birth-weight infants.

Background: Preterm infants fed fortified human milk (HM) grow more slowly than those fed preterm formulas. These differences could be related to the variability in the macronutrient composition of expressed HM, resulting in inadequate nutrient intake in relation to the estimated needs of the preterm infants.

Objectives: The aim of this article was to show the variability in HM composition from an infant's own mother's milk (OMM) or pooled HM from the milk bank. The second objective was to evaluate the advantages of individual fortification on nutritional intakes over standard fortification.

Design: The macronutrient composition of 428 OMM, 138 HM pools from single donors, 224 pools from multiple donors, and 14 pools from colostral milk was determined by using a mid-infrared analyzer. Individualized fortification was performed after analysis of the milk samples in 2 steps: adjustment of fat content up to 4 g/dL, followed by the addition of an HM fortifier to provide 4.3 g · kg(-1) · d(-1) according to the daily prescribed volume of feeding. Nutritional intakes resulting from the individualized fortification were compared with calculated intakes resulting from standard fortification (HM fortifier: 4 packets/dL).

Results: The variability in contents of fat, protein, and energy was high for all types of HM samples. Compared with standard fortification, individual fortification significantly reduced the variability in nutritional intakes, allowing the maintenance of protein intake and the protein:energy ratio in the range of the nutritional recommendations.

Conclusions: The variability in expressed HM with respect to its protein and energy content is high. This variability persists after standard fortification, possibly resulting in under- or overnutrition. Because both over- and undernutrition confer risks in later development, individualized fortification optimizes protein and energy intake.