Lactoferrin

Lactoferrin is an iron-binding glycoprotein of the transferrin family. In humans it is produced by epithelial secretory cells and released by neutrophils, and it is found in high concentrations in milk—especially colostrum—and in other secretions such as tears, saliva, and mucosal fluids. Lactoferrin is also present in blood as part of neutrophil granules and can be released during inflammation.

The protein has two lobes, each capable of binding one ferric iron ion, and can exist in iron-free (apo) or iron-bound (holo) forms. Its iron-binding capacity supports antimicrobial activity by limiting iron availability to microbes (nutritional immunity). Lactoferrin can also interact with microbial surfaces and with components such as lipopolysaccharide.

In addition to iron sequestration, lactoferrin exhibits antimicrobial effects that include direct membrane disruption by derived peptides (lactoferricin) and modulation of the immune response. It shows activity against a range of bacteria, viruses, and fungi and is associated with anti-inflammatory and immunomodulatory effects in mucosal tissues.

Commercially available bovine lactoferrin is widely used as a dietary supplement and as an ingredient in infant formula to emulate some of the lactoferrin content of human milk. Human and bovine lactoferrin differ slightly in sequence and activity, but both are used in research and products aimed at supporting immune defense.

Safety: lactoferrin used as a food ingredient is generally regarded as safe in approved contexts; dairy-allergic individuals should avoid it. High-dose clinical studies have largely found tolerability, with occasional mild gastrointestinal symptoms.