Effects of -lactalbumin–enriched formula containing different concentrations of glycomacropeptide on infant nutrition

Background: Formula-fed infants have growth and plasma amino acid patterns different from those of breastfed infants. Objective: -Lactalbumin is a major protein in human milk, and the addition of bovine -lactalbumin to infant formula has been proposed to modify the plasma amino acid pattern of the recipient infant, possibly allowing a reduction in the protein content of the formula, which may affect growth. Design: We compared breastfed infants and infants fed standard formula or -lactalbumin–enriched formulas (25% of protein) with glycomacropeptide accounting for 15% or 10% of the protein. The protein content of each formula was 13.1 g/L. Ninety-six infants aged 6 2 wk were recruited. Anthropometric measures were recorded, and interviews were conducted at enrollment and monthly until 6 mo of age. Blood samples were collected at enrollment and at 4 and 6 mo. Results: Formula intake did not differ between groups, and weight gain in the -lactalbumin–enriched formula groups were similar to that of the breastfed infants. The standard formula group gained significantly more weight than did the breastfed infants. All formulafed infants had significantly higher plasma concentrations of most essential amino acids at 4 and 6 mo than did the breastfed infants, and serum urea nitrogen was also higher in the formula-fed infants. Insulin and leptin concentrations did not differ between groups. Conclusions: Compared with standard formula-fed infants, infants fed formula with a modified protein composition had growth patterns more similar to those of breastfed infants. All formula-fed groups had plasma amino acid concentrations similar to or higher than those of breastfed infants. This indicates that the protein content of -lactalbumin–enriched formula can be further reduced, which should be evaluated. Am J Clin Nutr 2008;87:921–8.