Lactoferrin Lactoferrin (LF) is an iron-binding glycoprotein found in milk and various external secretions such as saliva, tears, airway secretion, and the granules of neutrophils, implying a important role in innate immunity. This protein has a number of biological functions, including antimicrobial, anti-tumor, antioxidant, and immunomodulatory effects. Partial degradation of LF by pepsin in stomach, may give rise to peptides termed lactoferricin with more potent antimicrobial activity. LF and lactoferricin have been shown to inhibit the growth of a number of pathogenic bacteria including antibiotic-resistant strains, fungi and even viruses in both in vitro and in vivo studies [9,10]. In mouse experiments, oral administration of bovine LF reduced bacterial infections in the gastrointestinal tract [9] while promoting the growth of bacteria with low iron requirements such as Lactobacillus and Bifidobacteria, which are generally believed to be beneficial to the host [11].