Protective Function of Proteins and Lipids in Human Milk

Abstract

Human milk provides the infant with protection against infectious diseases. This protection is conferred through several mechanisms: specific antibody targeted protection against pathogens in the infant’s environment (through milk IgA, IgG, and IgM) and broad-spectrum, nonspecific protection provided through several distinct mechanisms. These are: bactericidal effects (lactoferrin), bacteriostatic action (lactoferrin, lysozyme), lysis of microorganisms (lysozyme), antiviral effects (lactoferrin, products of milk fat digestion), antiprotozoan activity (free fatty acids produced during gastric and intestinal digestion of milk fat), and ligand action (inhibition of Helicobacter pylori adhesion to gastric mucosa by κ-casein). In addition to these protective functions of the proteins and lipids of human milk, several enzymes present in human milk might provide protection by generating components that are bactericidal (bile salt dependent lipase, peroxidase), prevent inflammatory reactions (platelet-activating factor acetylhydrolase), or protect the integrity of milk proteins (antiproteases).

The effect of bovine lactoferrin and lactoferricin B on the ability of feline calicivirus (a norovirus surrogate) and poliovirus to infect cell cultures

“…In addition, iron-saturated lactoferrin is relatively resistant to intestinal proteolytic enzymes (Brock et al 1976) and significant quantities of undigested and large fragments of lactoferrin have been isolated in the urine and faeces of infants subjected to oral administration of lactoferrin (Hamosh 1998;Parodi 1998). This suggests that lactoferrin can reach the small intestine and may therefore be available for prevention of infection by enteric viruses like noroviruses (for which the FCV has been used as a surrogate in this investigation).…”

Breastfeeding: making the difference in the development, health and nutrition of term and preterm newborns

“…Many nonspecific protective factors are found in human milk. Lactoferrin is a protein that acts as a bacteriostatic agent by depriving microorganisms of iron, in addition to exerting bactericidal, antiviral, anti-inflammatory and immunomodulatory activities 25,27 . Lysozyme is a protein component found in large amounts in human milk, which mediates bacterial lysis and can exert an immunomodulatory effect by releasing elements from the bacterial cell wall 25,27 .…”

“…Lactoferrin is a protein that acts as a bacteriostatic agent by depriving microorganisms of iron, in addition to exerting bactericidal, antiviral, anti-inflammatory and immunomodulatory activities 25,27 . Lysozyme is a protein component found in large amounts in human milk, which mediates bacterial lysis and can exert an immunomodulatory effect by releasing elements from the bacterial cell wall 25,27 . The components of the complement system are found in colostrum and mature milk, but in smaller amounts than those observed in maternal serum or in the nursing infant, and protect against respiratory and enteric infections.…”

Dioxin-like components in human breast milk collected from Hong Kong and Guangzhou

“…It is a general consensus that human milk is exclusively excellent for infant feeding, providing health and growth advantages for infants (Ellis et al, 1997;Garofalo and Goldman, 1998;Hamosh, 1998). However, a considerable number of studies has reported that the contamination of breast milk with organochlorine hydrocarbons may pose adverse health effects for the offspring.…”