Growth and metabolic response of premature infants fed whey- or casein-dominant formulas after hospital discharge.

We conducted a double-blind, randomized study to test the hypothesis that a whey-dominant formula permits a growth and metabolic advantage over a casein-dominant formula in preterm infants after hospital discharge. Nineteen low birth weight infants were studied for 6 months from the time of discharge. Ten received a casein-dominant formula, and nine received a whey-dominant formula. Growth (weight, length, head circumference, mid-arm circumference, and skin-fold thickness), biochemical measurements (alkaline phosphatase activity, acid-base status, and hemoglobin, serum total protein, albumin, and urea nitrogen levels), and quantity of formula intake did not differ significantly between the groups over a 6-month study period. Serum transthyretin and urea nitrogen concentrations differed significantly between the two feeding groups at the day of entry into the study only. The results indicate that, after hospital discharge, premature infants fed a whey-dominant formula do not differ in growth or biochemical measurements from those fed a casein-dominant formula.