Impact of fortifiers on donor milk nutrient composition: An experimental study

Preterm infants frequently require human milk fortification to meet their unique nutrients requirements. How commercial fortifiers change essential macronutrients and micronutrients in donor human milk has not been well-studied.

Our sampling frame included milk from approved United States milk bank donors (n = 400), measured for macronutrients, vitamins, and minerals, and used to produce 1000 pools of donor milk. Fortification ratios were computed to describe the extent that fortifiers changed donor milk composition (<100% indicates decreased; >100% indicates increased). Intake ratios were computed to evaluate how unfortified and fortified donor milk at 160 mL/kg/day compared to upper and lower preterm nutrient recommendations.

Fortifiers varied greatly in their impact on individual donor milk nutrients, with final macronutrient concentrations between 75% and 399% of unfortified values, while vitamin and mineral concentrations were between 50% and 800+% of unfortified values. Unfortified donor milk was able to meet the lower intake recommendations for three nutrients-lactose, fat, and pantothenic acid-highlighting the importance of utilizing multi-nutrient fortifiers. Bovine-derived fortifiers frequently did not meet lower targets for protein, choline, and several minerals, while human-derived fortifiers did not meet lower targets for most B-vitamins and choline, and exceeded some targets including protein, fat, calcium, phosphorus, and magnesium.

Fortification products available in the United States, when used with donor milk, frequently lead to both deficient and excessive nutrient intake compared to preterm enteral nutrition recommendations. Development of fortifier products based on robust nutritional reference values for donor milk is warranted to improve the nutritional care of preterm infants.