Digestion in the infant

Lactoferrin is the major whey protein present in breast milk (Teraguchi et ah, 1996) with many microbicidal properties (Leon-Sicairos et ah, 2006). The concentration of lactoferrin in milk has been reported as 1 g/liter in mature milk and 7 g/liter in colostrum (Houghton et ah, 1985). The concentration of lactoferrin in breast milk is controlled by the reproductive hormones prolactin and estrogen (Ward et ah, 2005). Lactoferrin has been demonstrated to resist digestion in the infant gut as it has been recovered intact from the stool of breast-fed infants (Bemt and Walker, 1999). Lactoferrin acts mainly in an iron-free state (apo-lactoferrin) and its microbicidal activity is reported to increase in proportion to its concentration in milk (Leon-Sicairos et ah, 2006). 

As shown in Figure 3.1, the concentrations of IgA and IgG decline in human breast milk in the weeks following birth. These antibodies tend to survive digestion in the infant s stomach because of its poor digestive powers and because the antibodies have structures that resist proteolysis. Breast-f infants are more resistant to enteric (intestinal) infections than formula-fed infants. Breast milk is espe-... 

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