Milk protein intake in the term infant. I. Metabolic responses and effects on growth.

Thirty healthy term infants were studied during the three first months of life. The infants were divided into three feeding groups consisting of 10 infants in each. The feeding regimens were: human milk by breast feeding, a formula (F-I) containing 1.2 g/100 ml of protein and a control formula (F-II) containing 1.6 g protein/100 ml. Both formulas were whey predominant and isocaloric. Protein intake was significantly higher with formula F-II when compared to the human milk group and to formula F-I. No significant differences with respect to weight, length and head circumference were found among the groups, but the rate of growth between 2 to 12 weeks was higher in the control formula (F-II) group. Serum albumin concentrations were normal and similar in all feeding groups. Blood urea nitrogen and urine total nitrogen concentration was significantly lower in the low protein formula I group when compared to the control formula II. After the fourth week of life the low protein formula infants had similar blood urea nitrogen and urine nitrogen concentrations as those of the breast-fed infants. The results indicate that current formulas in use provide excessive protein intakes after the first months of life.