What is Lactoferrin?
Lactoferrin is a multifunctional whey glycoprotein closely related to transferrin that has crucial antimicrobial, immune modulating, and anti-inflammatory properties. 1
Structure and Basic Properties
Lactoferrin is an 80 kDa iron-binding glycoprotein that belongs to the transferrin family 2. It has several key characteristics:
- Capable of binding 2 iron atoms with an affinity approximately 300 times higher than transferrin
- Retains iron even in acidic environments (down to pH 3)
- Present in various bodily fluids including milk, tears, saliva, and pancreatic juice
- Stored in specific granules of polymorphonuclear granulocytes (released upon activation)
- One of the most abundant proteins in human milk, accounting for approximately 25% of total milk protein content 1
Biological Functions
Lactoferrin serves multiple important physiological roles:
Antimicrobial Activity
- Exerts bactericidal effects by damaging the outer membrane of Gram-negative bacteria 3
- Withdraws iron from pathogens (iron sequestration)
- Directly interacts with bacterial cell walls, viruses, and parasites 1
- Binds with high affinity to lipid A (toxic component of lipopolysaccharide from Gram-negative bacteria) 3
Immunomodulatory Effects
- Regulates innate and adaptive immune responses
- Directly affects migration, maturation, and function of immune cells 1
- Decreases release of pro-inflammatory cytokines (IL-1, IL-2, TNF-alpha)
- Enhances monocyte and natural killer cell cytotoxicity 3
- Inhibits lipopolysaccharide interaction with CD14 on monocytes/macrophages 3
Iron Metabolism
- Regulates iron absorption in the intestine
- Can chelate iron directly or indirectly 4
- Lactoferrin receptors have been identified in the small intestine of infants and neonates 1
Additional Functions
- Anti-inflammatory properties
- Antioxidant activities
- Anti-cancer properties 4
- Influences gut microbiome composition 1
- Protects against oxidative DNA damage 5
- Protects mitochondria from dysfunction 5
Clinical Significance
Lactoferrin has several clinical applications and diagnostic uses:
Diagnostic Applications
- Used as a fecal biomarker for inflammatory conditions
- However, fecal lactoferrin detection should not be used to establish the cause of acute infectious diarrhea (strong recommendation) 1
- Lactoferrin is a normal component of human milk and may be present in varying amounts in stools of breastfed infants, making interpretation difficult in this population 1
Therapeutic Applications
- Supplementation with bovine lactoferrin has been studied for prevention of invasive fungal infections in premature infants 1
- May reduce the incidence of late-onset sepsis in infants <1500g 1
- Being investigated as adjuvant therapy for intestinal diseases 4
- Used in nutraceutical-supplemented infant formula and other food products 4
Important Considerations
- Despite its presence in breast milk and potential role in iron absorption, studies suggest lactoferrin may not be essential for high iron absorption in infants 1
- Early studies with bovine lactoferrin added to infant formula have not shown increases in iron absorption or improved iron status 1
- The exact mechanism of lactoferrin's role in iron absorption from human breast milk remains unclear and requires further research 1
Lactoferrin continues to be an important focus of research due to its diverse biological activities and potential therapeutic applications in managing infections, inflammation, and various diseases.