Addition of Calcium and Phosphorus to Preterm Donor Human Milk and the Impact on Protein, Fat, and Calcium Digestibility In Vitro

Abstract

Infants born prematurely are at risk for metabolic bone disease and may need increased minerals for normal bone mineralization. In these situations, supplementation of human milk with calcium and phosphorus is common in the United States. The interaction of these nutrients and their carriers with other nutrition components of human milk has not been systematically investigated. The primary goal was to study the effect of calcium and phosphorus supplementation on the digestibility of protein, free fatty acids, and calcium in preterm donor human milk (DHM). An in vitro model of the premature infant’s gastrointestinal tract was used to simulate digestion. Protein, free fatty acids, and ionized calcium were measured before and after in vitro digestion in milk with and without added calcium glubionate and sodium potassium phosphate. Calcium and phosphorus supplementation did not negatively affect total protein, protein breakdown, protein digestibility, or fat breakdown when compared with unfortified DHM. Supplemental calcium increased ionized calcium, which may replace ionized calcium lost during milk expression, storage, and processing. Supplemental calcium glubionate and sodium potassium phosphate do not affect protein or fat breakdown in vitro. DHM contains less ionized calcium than fresh human milk because it loses CO2during expression and processing. Adding supplemental calcium increases ionized calcium in DHM.