A randomized, controlled evaluation of two commercially available human breast milk fortifiers in healthy preterm neonates

Objective: To evaluate the added nutritional value of the two commercially available human breast milk fortifiers: Similac Natural Care (NC) and Enfamil Powder (EP). Design: A randomized controlled evaluation in healthy preterm neonates. Setting: Neonatal Intensive Care Unit, Royal University Hospital, Saskatoon, Saskatchewan, and Neonatal Intensive Care Unit, Jewish General Hospital, Montreal, Quebec, Canada. Subjects: Healthy preterm infants admitted to and cared for in the aforementioned neonatal intensive care units. Interventions: Healthy preterm neonates who were receiving expressed breast milk from their own mothers were supplemented with human milk fortifiers (NC and EP) per manufacturer's recommendations. Main outcome measures: Gestational age and birth weight, gender, and race. At entry to and exit from the study, serum concentrations of albumin, protein, calcium, phosphorus, and alkaline phosphatase. The age at which the supplements were added and the number of days the infant remained in the hospital. Daily weight gain, head circumference, length, and height were also measured. Statistical analyses performed: Student's t test was used to test the differences between the groups and within the groups at entry to and exit from the study. Fisher's exact test was used to determine differences in race, size, and gestational age in each group. When necessary, a chi-square test was used to analyze the preponderance of either sex in each group. A Wilcoxon rank test was applied to the true exit date to determine whether the bias was comparable in each group. Results: The mean (+/- standard error) gestational age and birth weight were similar in both groups: 30+/-0.3 weeks and 1,314+/-40 g, respectively, for NC vs 29.6+/-0.35 weeks and 1,262+/-45 g, respectively, for EP. At entry to the study, values for the NC group (N=29) were albumin 31+/=1.2 g/L, serum protein 48+/-1.4 g/L, calcium 2.4+/-0.03 mmol/L, phosphorus 1.85+/-0.08 mmol/L, alkaline phosphatase 347+/-27 IU/L. The values for the EP group (N=30) were albumin 32+/-0.9 g/L, serum protein 49+/-1.4 g/L, calcium 2.4+/-0.4 mmol/L, phosphorus 1.9+/-0.1 mmol/L, alkaline phosphatase 420+/-34 IU/L. At the study exit, the values for the NC group were albumin 30+/-0.7 g/L, serum protein 45+/-0.9 g/L, calcium 2.4+/-0.3 mmol/L, phosphorus 1.96+/-0.07 mmol/L, and alkaline phosphatase 371+/-23 IU/L. The values for the EP group were albumin 32+/-1.0 g/L, serum protein 46.0+/-1.4 g/L, calcium 2.5+/-0.03 mmol/L, serum phosphorus 2.2+/-0.1, and alkaline phosphatase 367+/-27 IU/L. No significant differences were observed between groups at entry to and exit from the study. However, in the EP group the alkaline phosphatase decreased significantly (P=.02) from entry to exit and calcium increased significantly during the same period compared with the NC group (P=.003). The mean daily weight gain was 33+/-0.7 g for the NC group and 31+/-1 g for the EP group. The weekly gain in head circumference and body length were also similar in both groups: approximately 1 cm/week. Both groups tolerated the fortifiers well. Applications/conclusions: These findings suggest that both products provide the additional nutritional support necessary for optimal overall postnatal growth in healthy preterm infants. The differences in calcium and alkaline phosphatase may be due to the differences in vitamin D content in fortifiers 88 IU/100 mL in mixed NC vs 276 IU/100 mL in mixed EP. This observation calls for careful monitoring of calcium and alkaline phosphatase values and possible adjustments of vitamin D intake when fortifiers are used for extended periods.