Objective: Excess protein in infant formula may lead to renal overload and play a role in later obesity. The objective of this controlled, prospective, randomized, double-blind study was to assess the suitability and safety of a modified protein content infant formula and its noninferiority as compared to a conventional formula.
Patients and methods: Healthy term infants age < 7 days were either breast-fed or randomized to be fed exclusively with a conventional casein-predominant formula (protein/energy ratio: 2.6 g/100 kcal) or the isocaloric whey-predominant study formula (protein/energy ratio: 1.8 g/100 kcal) for 120 days. Primary outcome was daily weight gain between D0 and D120 (noninferiority criterion: difference in daily weight gain < or = 4 g). Secondary outcomes were daily gain in weight, length, head circumference and body mass index at monthly intervals. Tolerance and safety were assessed at each visit.
Results: 162 infants were enrolled, 84% of the formula-fed infants and 36% of the breast-fed infants completing the study. Mean daily weight gain from D0 to D120 in the formula-fed groups differed by 0.38 g/day [95% CI: -2.59; 1.83] signifying the noninferiority of the study formula. Secondary outcomes did not differ between the 2 groups at any time and were comparable to outcomes in the breast-fed group. Tolerance was good and adverse events were not different between study groups.
Conclusions: The whey-predominant study infant formula with a protein/energy ratio of 1.8 g/100 kcal and enhanced protein efficiency is safe and not inferior to a conventional formula in ensuring normal growth during the first four months of life.