1. Introduction
gastrointestinal tolerance, breast-fed, Breast milk, overweight, breast milk
SECONDARY
Protein intake is higher in formula-fed than in breast-fed infants during infancy, which may lead to an increased risk of being overweight. Applying alpha-lactalbumin (α-lac)-enriched whey or casein glycomacropeptide (CGMP)-reduced whey to infant formula may enable further reduction of formula protein by improving the amino acid profile. Growth, nutrient intake, and protein metabolites were evaluated in a randomized, prospective, double-blinded intervention trial where term infants received standard formula (SF:2.2 g protein/100 kcal; Early nutrition influences growth and health in infancy and can impact long-term health and well-being. Breast milk, containing all nutrients in optimal proportions, is the best source of nutrition for the rapidly growing infant [According to the current EU regulation, protein concentration in commercial infant formulas should range from 1.8 g/100 kcal to 2.5 g/100 kcal [Infant formula composition has continuously changed over the years to resemble that of breast milk, the gold standard. Hence, the whey to casein ratio in infant formulas has been adjusted from 20/80 in bovine milk to 60/40 in infant formulas. Alpha-lactalbumin, the major whey protein in breast milk accounting for approximately 25% of the total protein content (2.5–3.0 g/L), or about 36% of the whey protein, is still low in standard infant formulas due to its lower concentration in bovine milk, i.e., 3.5% of total protein, or 17% of the whey protein [An alternative way to lower the total formula protein concentration is to use a whey fraction reduced in casein glycomacropeptide (CGMP). CGMP is a cleavage-product of bovine ĸ-casein, which contributes to an unfavorable amino acid profile with lack of essential aromatic amino acids such as tryptophan, phenylalanine, tyrosine and also cysteine, but is instead rich in threonine, proline, glutamine and serine [However, addition of CGMP-reduced whey could thus allow a reduction of total protein content, still providing adequate concentrations of essential amino acids. The primary objective of this study is to evaluate the effect on growth of infants between two and six months of age fed protein-reduced infant formula, either enriched in α-lactalbumin or reduced in CGMP. Our secondary objectives are to evaluate possible effects on nutrient intake and energetic efficiency, as well as on markers of protein metabolism, hematologic parameters, gastrointestinal tolerance, crying time, and time to fall asleep. 