Glycomacropeptide and [alpha]-lactalbumin supplementation of infant formula affects growth and nutritional status in infant rhesus monkeys

Background: Advances in dairy technology make it possible to enrich infant formula with specific bovine milk components that may enhance nutrient status. Glycomacropeptide, a carbohydrate-rich casein peptide, may increase absorption of calcium, iron, or zinc. [alpha]-Lactalbumin, a major breast-milk protein, may contribute to a balanced amino acid pattern and increase calcium and zinc absorption. Objective: We determined the effects of glycomacropeptide- and [alpha]-lactalbumin--supplemented infant formula on growth; trace mineral status; iron, zinc, and calcium absorption; and plasma amino acid, blood urea nitrogen, and plasma insulin concentrations. Design: Infant rhesus monkeys (n = 5 infants per group) were breastfed or fed control or [alpha]-lactalbumin--or glycomacropeptide-supplemented formula from birth to 4 mo of age. Hematologic measures and growth were assessed monthly. Mineral absorption was measured with radioisotopes and whole body counting. Results: Infants fed glycomacropeptide had higher food intake than did other formula-fed infants. Infants fed glycomacropeptide or control formula had higher hematocrit values than did infants that were breastfed or fed [alpha]-lactalbumin. Infants fed glycomacropeptide or control formula had higher plasma zinc and zinc absorption than did breastfed infants. Where differences were observed, breastfed infants and infants fed [alpha]-lactalbumin had similar plasma essential amino acid and insulin profiles, which were different from those of infants fed glycomacropeptide or control formula. Conclusions: Glycomacropeptide- or [alpha]-lactalbumin--supplemented formula has no adverse effects on nutritional status in infant monkeys. Glycomacropeptide supplementation increases zinc absorption, which may permit the reduction of formula zinc concentrations, and [alpha]-lactalbumin supplementation promotes a plasma amino acid pattern similar to that of breastfed infant monkeys. Am J Clin Nutr 2003;77:1261-8. KEY WORDS Glycomacropeptide, [alpha]-lactalbumin, formula, infants, monkeys, amino acids, trace minerals