Lactoferrin, sometimes called lactotransferrin, is an iron-binding glycoprotein of the transferrin family found in the milk of most mammals — and in tears, saliva and neutrophils — giving colostrum a faint pink tinge. Far more abundant in human milk (where it may account for up to 20% of total whey protein) than in cow’s milk, it starves bacteria of iron by chelation, particularly Gram-negative species with high iron needs, and also disrupts microbial membranes directly. This antibacterial and immunomodulatory action is valuable in infant formula (bovine lactoferrin supplementation), functional foods and natural preservation; it is heat-sensitive, so gentle processing preserves activity.