Nutritional and Physiologic Significance of α-Lactalbumin in Infants

Abstract

alpha-Lactalbumin is the major protein in breast milk (20-25% of total protein) and has been described to have several physiologic functions in the neonatal period. In the mammary gland, it participates in lactose synthesis, thereby creating an osmotic "drag" to facilitate milk production and secretion. alpha-Lactalbumin binds divalent cations (Ca, Zn) and may facilitate the absorption of essential minerals, and it provides a well-balanced supply of essential amino acids to the growing infant. During its digestion, peptides appear to be transiently formed that have antibacterial and immunostimulatory properties, thereby possibly aiding in the protection against infection. A novel folding variant ("molten globule state") of multimeric alpha-lactalbumin has recently been discovered that has anti-infective activity and enhances apoptosis, thus possibly affecting mucosal cell turnover and proliferation. Cow milk also contains alpha-lactalbumin, albeit less than human milk (2-5% of total protein in bovine milk), and protein fractions enriched with alpha-lactalbumin may now be added to infant formula to provide some of the benefits of human alpha-lactalbumin.

α-Lactalbumin-rich infant formula fed to healthy term infants in a multicenter study: plasma essential amino acids and gastrointestinal tolerance

“…HM whey proteins play an important role in many physiologic activities that benefit the infant such as immune function and nutrient absorption (Lonnerdal and Lien, 2003). a-Lactalbumin in HM has been shown to bind minerals such as calcium (Lonnerdal and Glazier, 1985) and zinc (Ren et al, 1993) facilitating their absorption (Lonnerdal and Lien, 2003).…”

IEC-6 Intestinal Cell Death Induced by Bovine Milk α-Lactalbumin

“…In addition, dairy products, including infant formulas, appear to be prone to increase in concentration. 3,24) In the small intestine, a persistent low frequency of spontaneous apoptosis can be seen in the crypts of healthy animals and humans. 25) This is important for maintaining stem cell numbers as a protective mechanism.…”

“…-lactalbumin (-LA) is a protein with a molecular mass of 14-kDa present in the milk of all mammals. 2,3) The protein is a calcium metallo-protein, essential for folding and structural stability. 4) Its main biological function is to act as a specifier protein for lactose synthetase in the formation of lactose from galactose and glucose.…”

Bioactive peptides released from in vitro digestion of human milk with or without pasteurization

“…α-Lactalbumin is a rich source of essential amino acids and of central importance to the rapidly growing neonate (35), and it has also been reported to provide various bioactive peptides (11). In vitro digestion of HM and pasteurized HM released an ACEi peptide (residues 104-108) (28).…”