Whey protein and colostrum

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). 

Nutritional significance. As one of the major whey proteins in human milk and also relatively abundant in bovine colostrum, LF is of interest as a dietary source of amino acids as well as for the bioavailability of iron. LF has an... 

Studies in human adults using radioisotopes or stable isotopes of Zn showed that Zn absorption is higher from human milk (41 percent) than from cow (28 percent) or soy formulas (14 percent) [77]. In any case, it seems that there is no need to fortify cow-based formulas with Zn, since cow milk contains much more Zn than breast milk [77]. However, Zn bioavailavility from breast milk is clearly higher than from formulas, which indicates a different composition in Zn species. Experiments in speciation of Zn in formula milk whey carried out by SEC showed that Zn was mostly found in the LMW (< 10 kDa) fraction, as a complex of citrate and only a small fraction of the metal was bound to whey proteins (435 kDa) [15, 18, 21]. Although such species are detected in human milk, important differences have been found between the distribution patterns of Zn in breast milk and in cow-based formula milks (see Fig. 17.11 and compare with Fig. 17.4). The levels of Zn in formulas are higher than in human milk and in colostrums [18]. 

Korhonen, H. J., Mine, Y., Li-Chan, E., Jiang, B., 2010. Health-promoting proteins and peptides in colostrum and whey. Bioactive Proteins and Peptides as Functional Foods and Nutra-ceuticals 29, 151. 

Immunoglobulins are present in milk and may transfer passive immunity to people who ingest them. Colostrum has the highest component of immunoglobulins and is present in milk, but whey protein still has immunoglobulins. 

It is interesting to note that /3-lactoglobulin is the major protein in cow s milk whey, but it is absent from human milk whey. However, the content of a-lactoalbumin and immunoglobulins (Ig) is higher in human than in cow s milk whey. Serum albumin and lactoferrins are found in similar concentrations in human and cow s milk whey, and the amount of lactoferrin is higher in colostrum than in mature milk. In any case, lactoferrin is present in milk throughout the lactation period. 

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