Whey Proteins in Feces of Preterm Infants Receiving Preterm Milk and Infant Formula
Human milk whey contains proteins thought to have functional and nutritional roles for the infant. These proteins include lysozyme(Lys), lactoferrin(Lf), secretory IgA(sIgA), serum albumin(SA) and α-lactalbumin(α-LA). SA and α-LA primarily have nutritional importance as sources of amino acids. Lys, Lf and slgA may have both nutritional and physiological functions. Lys and Lf have been suggested to have bacteriostatic effects within the infant’s gastrointestinal (GI) tract. SlgA acts immunologically within the gut of the infant. For these proteins to exert their functions, they must remain largely intact during passage through the upper GI tract. We have demonstrated (AJCN 41: 852(1985)) that LF and slgA are detected in feces of exclusively breast-fed term infants. We were interest in quantitating these proteins in feces of preterm infants for two reasons. First, preterm milk contains higher quantities of these whey proteins. Secondly, the proteins may serve a greater protective role for preterm infants, due to immature immune function in such infants.