87 FORMULA WITH REDUCED PROTEIN CONTENT IN TERM INFANTS DURING WEANING: RESPONSES ON GROWTH AND NITROGEN METABOLISM

Abstract

20 healthy term infants between 4 and 6 months of age were randomly assigned to either a low protein formula (LP) containing 1.3 g protein/dl or a high protein formula (HP) containing 1.8 g/dl. Both were isocaloric (72 kcal/dl) and had a whey-casein ratio of 50:50. 10 control infants were breast-fed (BF). The mean protein intakes were: 1.9, 2.6 and 1.3 g/kg/d respectively. The mean concentrations of serum urea were 2.8 (LP), 4.1 (HP) and 2.2 mmol/l (BF) at 6 months (HP vs BP p<0.001). The urine excretion of nitrogen were similar in the BE and LP groups, being 75 and 81 mg/kg/d. In the HP-group nitrogen excretion was markedly higher, 138 mg/kg/d. Plasma concentrations of albumin, prealbumin and transferrin were normal and similar among the groups. The concentrations of methionine, threonine, leucine, isoleucine, valine, tyrosine and phenylalanine were significantly elevated in the infants in the HP-group when compared to the BF-group. Weight gain was significantly higher in the HP-group 22.8±1.7 g/kg/week when compared to the LP- and BF-groups, 19.9±3.9 and 18.0±4.3 (p<0.01) respectively. These data indicate that a decreased protein intake from a whey adapted formula during weaning results in many indices of protein metabolism and growth more similar to those found in breast-fed infants than when conventional high protein formulas are used.