Background: Because recent data on the effects of mineral concentrations in preterm infant formula on bone mineralization are lacking, recommendations for the mineral content of preterm infant formula differ greatly between committees.
Objective: The goal of the study was to assess the effects of an isocaloric, nutrient-enriched preterm formula, which was fed from the age when full enteral feedings were tolerated through expected term, on bone mineralization in preterm infants.
Design: We conducted a prospective, randomized, double-blind study in healthy, preterm infants (gestational age of 28-32 wk) who were fed either a control preterm formula (n=20) or an isocaloric, nutrient-enriched preterm formula (n=21) until 3 mo of age (ie, approximate expected term). Serum calcium indexes were taken throughout the study, and bone mass was determined by using dual-energy X-ray absorptiometry at hospital discharge and expected term.
Results: A total of 37 infants (experimental formula, n=19; control formula, n=18) completed the study. Compared with control subjects, infants fed the experimental formula had 25% and 40% higher intakes of calcium and phosphorus, respectively. Serum calcium, phosphorus, osteocalcin, and alkaline phosphatase concentrations and urinary collagen type I cross-linked N-telopetide concentrations were not significantly different between the groups at any time point. The bone mineral content of infants fed the experimental formula was 23% (P=0.039) and 35% (P=0.002) higher at hospital discharge and expected term, respectively.
Conclusions: Bone mineralization at hospital discharge and expected term was significantly higher in preterm infants fed the isocaloric, nutrient-enriched formula than in those fed control formula. Continuation of the experimental formula beyond hospital discharge, through expected term, further improved bone mineralization.