Lactoferrins

Lactoferrins are iron-binding glycoproteins that belong to the transferrin family and are found in high concentrations in milk, other secretions, and in neutrophil granules. The best-characterized member is human lactoferrin (hLF); several other lactoferrins occur in mammals, most notably bovine lactoferrin. The lactoferrin protein is composed of two homologous lobes, each capable of reversibly binding one ferric ion, and exists in iron-free (apo) and iron-saturated (holo) forms. The LTF gene encodes lactoferrin in humans.

Lactoferrins are present in colostrum and mature milk, as well as in saliva, tears, mucus, and other secretions. In humans, neutrophils store lactoferrin in secondary granules and release it at sites of inflammation, contributing to local antimicrobial activity.

Functional roles include antimicrobial effects through iron sequestration, which limits nutrient availability for many pathogens, and direct interactions with microbial membranes. Lactoferrins also show antiviral and antifungal activity, and can modulate immune responses by influencing cytokine production and the activity of immune cells. In the gut, lactoferrin supports barrier function and can shape the microbiota.

Applications and research: lactoferrin is added to some infant formulas and studied for therapeutic uses in infection, inflammation, and wound healing. Evidence supports antimicrobial and anti-inflammatory properties in vitro and in animal models, but clinical guidance remains limited and results in humans are mixed.

Safety and regulation: lactoferrin used as a food ingredient is generally regarded as safe for most populations; as with any supplementation, use should consider individual conditions, particularly in infants and people with iron disorders. Overall, lactoferrins exemplify a component of innate immunity linked to nutrition.