|
| |
Lactoferrin Nature's
Premier Immune-Boosting Protein
Geoff Kwait, Ph.D.
Infants receive valuable assistance from their
mothers breast milk to combat infection and disease during the critical neonatal
period when their immune systems are not yet fully functional. While breast milk
contains a myriad of biologically active molecules,1 one in particular,
lactoferrin, has recently received extensive attention from research scientists,
health practitioners, and the general public.
Why all the interest Well, to begin with, anecdotal evidence of healing
attributed to lactoferrin when taken as a nutritional supplement is plentiful.
Some accounts with respect to cancer, immune deficiency and other afflictions
are described as nothing short of miraculous. From a more scientific
perspective, basic research on the molecular, cellular, and physiological
properties of lactoferrin has increased tremendously in the past few years as
the results of each new study generate further interest and excitement. So great
is the promise of this protein, discovered over 30 years ago, that research is
being encouraged by the National Institutes of Health. Here, I describe
biological characteristics and properties of lactoferrin as revealed in recent
scientific studies and include a sampling of the therapeutic miracles attributed
to it.
The name lactoferrin is derived from its affinity to bind with iron (lacto =
milk; ferrin = iron). In fact, lactoferrin binds iron over a hundredfold more
strongly than transferrin, the major iron transport protein in the body. The
highest known concentrations of lactoferrin are found in human colostrum, or
first milk, where levels measure as much as 7 grams/litre. Mature human milk
contains considerably less, about 1 gram/litre. A similar pattern exists in
bovine (cow) milk, but the levels are not as high as in human milk. Lactoferrin
is also found in neutrophils (a type of leukocyte or white blood cell), and, to
a lesser extent, in the secretions of tear glands, salivary glands and the
prostate gland.
Lactoferrin is a protein molecule comprised of a single strand of amino acids.
For reasons not completely understood, lactoferrin, compared to other proteins,
is remarkably resistant to degradation, a trait that may prolong functional
activity following oral ingestion. The lactoferrin molecule is also
characterized by the existence of distinct functional domains. For example, one
region has ribonuclease activity, i.e., the ability to break bonds within
nucleic acid molecules such as ribonucleic acid (RNA). Another region is
responsible for lactoferrins iron-binding properties. Both the ribonuclease
activity and iron-binding capacities of lactoferrin have been implicated in the
antimicrobial effects of lactoferrin, described below.
The locations of receptors for a biologically active substance in different
tissues often provide clues as to its actions, or at least the site of its
actions. Receptors to which lactoferrin presumably binds in the course of its
biological effects have been found in intestinal tissues, in the brain, on the
surface of several types of white blood cells, on blood platelets, and on
certain bacteria. Evidence described recently in the scientific journal Nature,
suggests that lactoferrin can bind to regions of DNA in the cell nucleus and
directly influence the activity of genes that code for the cells proteins.
Role In Immune System
A strong case can be made for lactoferrins central role in the immune system.
The biological actions of lactoferrin under various experimental conditions are
wide-ranging and include: inhibition of the survival or growth of many different
pathogenic organisms; activation or stimulation of a variety of immune system
cells; regulation of normal cell growth; and inhibition of abnormal tumour
growth and spread of cancer cells in laboratory animals.
Physiological concentrations of lactoferrin are capable of killing or inhibiting
the growth of a wide spectrum of infectious organisms including bacteria,
viruses, parasites and fungi. One mechanism probably involved in at least some
of the anti-microbial effects of lactoferrin is that, by strongly binding iron,
lactoferrin deprives foreign organisms of essential iron. Interestingly,
friendly bacteria, i.e., those that have beneficial effects in the
gastrointestinal tract (e.g. Lactobacillus acidophilus, Lactobacillus bifidus
and Lactobacillus G.G., may be resistant to such effects by virtue of the fact
that they are less dependent on exogenous sources of iron. Other proposed
mechanisms for lactoferrins antimicrobial actions relate to the ability of
lactoferrin to interfere with the carbohydrate metabolism of invading organisms
or lactoferrins ribonuclease activity, which may interfere with the organism’s
ability to synthesize RNA essential for microbial protein synthesis.
Fortunately, lactoferrin does not appear to adversely interfere with these
processes in the human host’s cells.
Bacterial Inhibition
Examples of specific bacteria inhibited by lactoferrin include: Staphylococcus
aureus, Escherichia coli, Klebsiella pneumoniae, and Helicobacter pylori, all of
which are capable of causing serious illness. Helicobacter pylori has recently
been identified as a primary culprit in the development of stomach ulcers. While
many studies have involved observations of lactoferrin's effects on microbial
growth in a laboratory dish or test tube, recent research in Japan has
demonstrated that, when administered orally to mice, bovine-derived lactoferrin
causes a marked reduction in the proliferation of intestinal bacteria, including
several strains of the pathogenic bacterium, Clostridium. Furthermore, when
administered to laboratory animals, lactoferrin also decreases the number of
bacteria that translocate, or pass through, the cell lining of the intestines.
Translocation of bacteria through the intestinal epithelium is a means by which
bacteria can gain access to the blood and lymphatic system, and, if they are not
checked by the body's immune system, infections and illness ensue.
Antiviral Effects
Potent antiviral effects have been described for lactoferrin. Human
cytomegalovirus, human herpes simplex virus-1, and human immunodeficiency virus
(HIV, the virus responsible for AIDS) all have been inhibited by lactoferrin in
laboratory experiments. Viral infections are believed to be involved in the
etiology of certain types of leukaemia. In an experimental model in which mice
are infected with a virus that produces conditions similar to leukaemia, mice
given lactoferrin fared significantly better than control mice in terms of the
degree of illness.
Antifungual and Antiparasite
As mentioned previously, lactoferrin also inhibits several species of fungi and
certain parasites. Fungi inhibited by lactoferrin include Candida albicans, the
form of yeast normally present to some extent in all individuals, but
responsible for yeast infections, or aggressive fungal overgrowth. The mechanism
by which lactoferrin inhibits some parasites may be via stimulation of the
process of phagocytosis, whereby immune cells engulf and digest foreign
organisms.
Antimicrobial Functions
Lactoferrin present in gland secretions may serve an antimicrobial function.
Saliva, for example, aids in the prevention of dental cavities by virtue of
antibacterial properties attributed to lactoferrin and antimicrobial enzymes
like lysozyme and peroxidase. Insufficient amounts of lactoferrin in some
secretions also appear to correlate with certain health problems. Low
concentrations of lactoferrin present in lacrimal secretions of some patients
with acquired immune deficiency syndrome (AIDS) may contribute to ocular dry
syndrome, a condition characterized by eye tissue deterioration and insufficient
tear secretion.
Immunosupportive
Lactoferrin affects the proliferation, maturation and activation of several
types of immune cells. Evidence suggests lactoferrin regulates the maturation
and activation of neutrophils and macrophages, the immune cells primarily
responsible for phagocytosis. Neutrophils secrete lactoferrin during
inflammation. Lactoferrin also affects, in a number of ways, the maturation and
function of lymphocytes, another major class of immune cells that includes cells
responsible for antibody secretion and cells that directly attack foreign
organisms. One notable study demonstrated that lactoferrin prevents fatal
cytomegalovirus infections in mice. It does this by augmenting the action of
lymphocytes called natural killer T-cells that attack and destroy the viruses.
Without lactoferrin, test mice succumbed to the viral infection.
Cytokines
At the biochemical level, lactoferrin appears to modulate immune function
through cytokines. Cytokines belong to a broad class of molecules that regulate
interactions between various cells in the body. Cytokines that specifically
regulate interactions between white blood cells, or leukocytes, are called
interleukins. Recent lactoferrin research has focused on the ability of
lactoferrin to regulate release or actions of interleukins and other cytokines.
Maternal Immune Suppression
An appealing theory on lactoferrin and immune function has been put forth (see
ref. 3) that relates to the natural immune suppression that occurs in women
during pregnancy. Immune suppression at this time is believed to help avoid
maternal rejection of the foetus. According to this theory, increased
lactoferrin production in the mother at the time of birth may be a major factor
in restoration of maternal immune function and at same time
help to prevent infection in the newborn via breast milk. Unfortunately, the
natural immune suppression that occurs during pregnancy may manifest itself
abnormally at other times the consequence being immune deficiency and disease
(e.g. AIDS). Reasoning follows that, if lactoferrin is an essential immune
system regulatory protein, as evidence suggests, then deficiencies in production
of lactoferrin during both childhood and adulthood alike could be responsible
for various health problems associated with a dysfunctional immune system.
Anecdotal evidence indicates that lactoferrin is beneficial in some AIDS cases.
Cancer Inhibition
With respect to cancer, lactoferrin has been shown to inhibit the growth of some
solid tumours and inhibit experimental metastasis, or spread of cancer cells, in
laboratory mice. Research conducted in Japan studied the effects of
bovine-derived lactoferrin in mice that were inoculated with cancer-like cells
intended as a model for either skin cancer or leukaemia. The cancer cells used
in these experiments are known to be highly metastatic, i.e., they easily spread
from a solid tumour site to invade other organs and tissues. When lactoferrin
was administered just after tumour formation, the growth of tumour cells was
suppressed and the spread of the cancer cells to the lungs and liver was
significantly less than in control animals that did not receive lactoferrin.
Angiogenesis Suppression
Several possibilities have been described for how lactoferrin carries out its
anticancer effects. Japanese researchers have speculated that lactoferrin's
iron-binding capacity may be involved in the anticancer mechanism. Others think
lactoferrin acts directly on the cancer cells themselves, as suggested by
demonstrations that human lactoferrin binds to cell receptors on the surface of
certain cancer cells. Still other evidence suggests that lactoferrin acts
indirectly through stimulation of the killer T-lymphocytes which then attack the
cancer cells. Finally, lactoferrin also appears to suppress tumour-induced
angiogenesis, or blood vessel formation. Consequently, such suppression deprives
the tumour of nutrients needed to sustain its growth.
Anecdotal Evidence
In vitro and animal experiments strongly support the argument that lactoferrin
is part of an ongoing defence against tumours. But does it act similarly in
humans The actions of lactoferrin in humans are based largely on anecdotal
evidence, i.e., reports that have not been documented according to scientific
standards. Nevertheless, anecdotal accounts of results following lactoferrin
administration to humans with serious illnesses, under the supervision of health
practitioners, suggest that lactoferrin may be responsible for significant
improvements in human health. In one example, a seriously ill patient with lung
cancer was given lactoferrin by her prominent New York City physician, who
specializes in treating the terminally ill. Despite the poor prognosis, this
woman experienced a startling revitalization within weeks of first taking
lactoferrin, resulting in weight gain and increased muscle strength.
Another remarkable turnaround following the addition of lactoferrin as a dietary
supplement involves Gerry H. McAnulty, who suffered from scleroderma, a poorly
understood and severely disabling fibrotic disease of the skin and internal
organs. I talked to Ms. McAnulty prior to writing this article, and the change
in her condition that she attributes, in part, to lactoferrin could easily be
described by the spiritually unchallenged as a miracle. She feels she would not
be alive today were it not for lactoferrin. Her renewed vigour has inspired her
to become actively involved in women's health education issues.
Numerous other dramatic effects of lactoferrin taken as a nutritional supplement
have been described. I recently was informed of a case in which an individual
suffering from impotence was able to achieve an erection for the first time in
years after taking lactoferrin! The problem, of course, with interpreting these
testimonials is that it is difficult, if not impossible, to determine what
precisely was responsible for the dramatic recovery or effect. A combination of
treatments, psychological factors, or interactions between therapeutic agents
could be responsible. Or the events that transpire may be a natural course of
the illness or condition.
This
article is from
http://intelegen.com
|
