Comparison of calcium- and phosphorus-supplemented soy isolate formula with whey-predominant premature formula in very low birth weight infants

In a random, controlled study of very low birth weight (VLBW) infants from 3 to 8 weeks of age, 17 infants were fed soy isolate formula supplemented with calcium (92 mg/kg/day), phosphorus (44 mg/kg/day), and vitamin D (500 IU/kg/day), and 15 were fed a new whey-predominant, low osmolality formula designed for small preterm infants. Mean birth weight (1,206 g, SD 178) and gestational age (30 weeks, SD 1.9) of the soy-fed group were not significantly different from the whey formula group (1,143 g, SD 158, and 30 weeks, SD 1.8, respectively). Caloric and protein intakes were not different between the formula groups throughout the study period. However, mean weight gain in g/kg/day was significantly greater for the whey formula group: 15.3 g, SD 2.5, vs. 11.3 g, SD 2.3, p less than 0.0001. Serum protein and albumin were higher in the whey formula-fed group during the latter 2 weeks of the study (p less than 0.05). The incidence of vomiting, gastric residual, abdominal distension, diarrhea, and constipation was low and not different between the two groups. No infant developed necrotizing enterocolitis. Serum calcium, phosphorus, alkaline phosphatase, 25-hydroxy vitamin D and parathyroid hormone were similar in both groups, and no infant developed radiographic evidence of rickets. Although soy isolate formula supplemented with calcium, phosphorus, and vitamin D was not associated with rickets, no fewer complications were observed with this lactose-free, low solute formula.(ABSTRACT TRUNCATED AT 250 WORDS)