In the early 1930s, scientists discovered a peculiar protein in milk. They named the protein lactoferrin because it was rich in iron, but its function was then unknown. For a long time, researchers believed the protein was designed to help infants store iron because of its ability to bind to the metal.
It took thirty years before researchers began unraveling the mysteries behind lactoferrin. In 1960, scientists were able to fully purify lactoferrin from both human and cow milk, which helped pave the way for additional research into the structure and function of the protein.
Eventually, in 1977, researchers found evidence that lactoferrin had antimicrobial properties. Since then, scientists have discovered that lactoferrin acts against pathogenic bacteria, fungi, and viruses and has beneficial properties for the innate immune system of infants. They have even found that lactoferrin can suppress infectious diseases in adults.
The Health Benefits of Lactoferrin
Lactoferrin possesses potent antibacterial activity against a broad range of bacteria. Bacteria that are involved in gastrointestinal infections are susceptible to the effects of lactoferrin. These include Clostridium difficile, the leading cause of infectious diarrhea in hospitals, and Heliobacter pylori, a bacteria that increases the risk of peptic ulcers.
Bacteria that are involved in common foodborne illnesses are also inhibited or killed by the action of lactoferrin. For example, lactoferrin exhibits antimicrobial effects against Listeria monocytogenes, Shigella flexneri, Escherichia coli, Salmonella spp., and others, all of which are associated with food-borne outbreaks.
Research into the properties of lactoferrin has also shown that the protein can reduce the spread of fungal infections. In immunocompromised patients, lactoferrin works in synergy with antifungal drugs to inhibit the growth of Candida albicans, a pathogenic fungus that causes yeast infections and candidiasis in humans. Lactoferrin also affects the growth of Aspergillus fumigatus, a common fungus that is normally harmless but can infect immunocompromised individuals. Lactoferrin has also been shown to inhibit the replication of viruses such as rotavirus, which causes watery diarrhea in children, cytomegalovirus, a member of the herpes virus family, herpes simplex viruses, and HIV.
Lactoferrin may support infant gastrointestinal health as well, through several mechanisms. Lactoferrin can increase the maturation rate of the early intestinal lining, which protects infants from gastrointestinal infection by reducing the permeability of the lining. High concentrations of lactoferrin has been associated with increased levels of gut ‘friendly’ bacteria bifidobacteria and lactobacilli, as lactoferrin does not suppress their growth. Lactoferrin has been reported to increase the number of immune cells and immunity-promoting signaling molecules.
Lactoferrin has been used in a variety of products since it was first added to infant formula back in 1986. Lactoferrin is still added to infant formula to improve the long-term health of growing babies. The protein is also available as adult supplements to support their immune system.
How does Lactoferrin work
Clinical trials in the 1980s and 90s showed that lactoferrin had little to do with iron absorption in infants, despite its ability to strongly bind to iron. In fact, removal of lactoferrin from milk actually increased iron absorption.
The presence of lactoferrin in milk is believed to support the innate immune system by reducing the level of available iron in the environment.
Iron is a necessary nutrient for many pathogenic bacteria. Without sufficient concentrations of iron in their surroundings, many of these bacteria stop reproducing or simply die.
Lactoferrin can also directly bind to the cell membranes of fungi, damaging them in the process and creating holes in the membrane. This results in leakage of protein and cell membrane collapse, like a deflating balloon. Lactoferrin interferes with viruses in the same way. The protein binds to viral particles, inhibiting their ability to attach to and penetrate human cells.
While most lactoferrin remains intact in the stomach, the protein can be partially digested by enzymes to produce peptide fragments. These peptide fragments have been shown to exhibit similar biological activities compared to lactoferrin.
How is Lactoferrin produced
Human colostrum has the highest concentration of lactoferrin at 3.16 grams per liter, whereas transitional milk and mature milk has less, at concentrations of 1.73 grams per liter and 0.90 grams per liter, respectively.
Lactoferrin is produced and purified from skim milk and cheese whey using chromatography. The crude liquid is fed through resinous beads that selectively bind to lactoferrin, which can be collected by dislodging the lactoferrin protein with concentrated salt solutions. The crude lactoferrin is desalted using ultrafiltration membranes and freeze- or spray-dried to give a solid powder.
However, the process is expensive and limits the production of lactoferrin. Today, lactoferrin remains one of the most costly dairy ingredients available. And unfortunately, only lactoferrin from cow’s milk can be produced in this fashion. The differences in lactoferrin from cow and human milk are important to their function. They have different amino acid compositions and glycosylation patterns. Due to these molecular distinctions, human lactoferrin has stronger potency against certain strains of bacteria than lactoferrin derived from cows.
New technologies to produce bio-similar compounds to human milk components could lead the way to greater amounts of human lactoferrin, designed for humans. As a supplement or an additive in nutritional foods, the widespread inclusion of human lactoferrin could change the way we eat and live. By making human lactoferrin available to the world, everyone could potentially benefit from the potent immune-boosting properties of this protein.