Macronutrient Composition of Donated Human Milk in a New Zealand Population

A primary role of human donor milk banks is to provide pasteurized human milk for the sick and preterm infant populations and to support the mothers of these infants as they establish their own milk supply. The results of human milk pasteurization continue to be studied to provide information that enables optimal nutrition in this sick and preterm population.

The aims of our study were to determine macronutrient characteristics (fat, protein, carbohydrate) and energy content of human milk donated to the Christchurch Women's Hospital Human Milk Bank in New Zealand, and the influence of Holder pasteurization on this macronutrient composition.

This was a retrospective, pre/post pasteurization observational design to describe the macronutrient content within two groups of donors, mature preterm PDM (n = 13; 21%) and mature term PDM (n = 50; 79%). Sixty three samples of human milk donated to the human milk bank by 27 registered participants (mothers of preterm and term infants) were analyzed. This analysis took place July-September 2018 using a human milk analyzer before and after Holder pasteurization (62.5 °C for 30 min).

Preterm milk contained on average 76 kcal/100 ml energy, 4.0 g/100 ml fat, 1.1 g/100 ml protein and 8.2 g/100 ml total carbohydrate; and mature term milk contained 68 kcal/100 ml energy, 3.5 g/100 ml fat, 0.8 g/100 ml protein and 7.9 g/100 ml total carbohydrate. Wide variation between single, donor-pooled samples was demonstrated and there was no major result of pasteurization.

This research adds to the evidence regarding the macronutrient content of preterm and term milk and that these values are unaffected by Holder pasteurization. The variance in individual pooled donor human milk indicates the importance of determining the nutrient composition of donated milk to inform fortification procedures.