Enhancing Immune Function
Helping customers boost general well-being to fortify
defenses against pathogens
by Heather Granato

An intricate network of cells, tissues and organs, the immune system is at
the core of defining “self” and protecting the body from harm. Compromised
nutritional status can hinder the operations of this on-call protection, just as
many specialty compounds can promote healthy function and modulate its
interactions.
From the time of conception, the body develops methods of self preservation
despite external and internal toxins. At its core, immunity is simple. The body
discriminates between what is “you” (autologous or self) and “not you”
(foreign or non-self). Approaches to helping the immune system can either boost
(generally or specifically) a depressed immune system or mediate the immune
response. Suppressed immune response can lead to infectious disease, while
hyper-stimulated immunity is related to allergies or autoimmune problems.
“The field of immunology has changed dramatically in the last 20 year s ,
due in large part to the unique pathophysiology of the HIV virus,” said Omar
Cruz, professional educator, Gaia Herbs. “The introduction of such a
devastating disease has forced the medical community to focus on maintaining
wellness during chronic illness. This concept had already been developed in the
theories of preventive wellness and may have in fact reinforced the wellness
movement. We’re also seeing an increased prevalence of autoimmune disorders,
which is bringing focus onto the delicate balance between immune function and
dysfunction.”
Increased media attention on these conditions and the rise of pandemic
diseases (i.e., SARS, bird flu) have combined with other factors to increase
awareness of the importance of immune support. “The concern for maintaining
proper health and immunity is at the forefront of most people’s minds when
considering the high cost of health care, loss in production and pay due to
untimely illnesses, and their concern for the health of family, friends and
co-workers,” said Dawn Phimister, marketing coordinator, EcoNugenics. “The
growing base of research and knowledge is empowering individuals to realize they
can play a role in maintaining their health and be proactive in the maintenance
of that health.”
Larry
Robinson, Ph.D., vice president of scientific affairs, Embria Health Sciences,
agreed with the assessment. He said: “Consumers have gone from thinking of
immune health products as only needed for support during cold and flu season to
realizing that all aspects of human health are profoundly affected by the immune
system. Since the immune system is responsible for balancing pro-inflammatory
and anti-inflammatory responses, an improper immune response can lead to various
illness—not only colds and flu, but over time to chronic diseases.”To start
the conversation with consumers, it helps to understand the basics behind how
the body’s immune system works. The immune system includes white blood cells
(leukocytes, produced by stem cells in the bone marrow) and the lymphoid organs
(including the thymus gland, lymph nodes, spleen and Peyer’s patches). It
responds to infectious attack or internal mutation through both non-specific and
specific immunity.
Non-specific immunity, a.k.a. innate or passive immunity, includes the skin
and mucosal surfaces lining the respiratory and digestive tracts; those mucosal
surfaces contain defense cells such as macrophages and neutrophils, as well as
many types of immunoglobulins— antibodies that determine which non-self
organisms are pathogenic and which are innocuous. The cells and products of the
innate immune system influence the antibody and T cell responses of the adaptive
(e.g., active or specific) immune system. Two types of lymphocytes—B cells and
T cells—are at the core of adaptive immunity. (One other type of lymphocyte is
the natural killer, or NK, cell. This cell is non-specific but active in seeking
out tumor or virally infected cells.) B cells are produced in the stem cells of
bone marrow and oversee humoral immunity, the link to antibody reaction. T cells
are also produced in bone mar row but are sensitized in the thymus, and are at
the basis of cell-mediated immunity, responding to the body’s own cells that
have changed in response to a viral invasion or cellular mutation. There are
several types of T cells, though the cytotoxic and helper T cells are best
known. Cytotoxic T cells release lymphotoxins to cause cell death and attract
macrophages to clean up the area, and helper T cells, known as CD4 or CD8 cells,
stimulate the activity of cytotoxic T cells.
“If the immune system is strong and healthy, the lymphocytes can destroy
intruding antigens with the efficiency of an elite, well-trained team of Army
Special Forces,” said Hank Cheatham, director of sales and mar keting, Quality
of Life Labs .
“Maintaining a healthy immune system provides a much greater chance of
long-term health than hoping a therapy will be able to persevere in the face of
literally millions of diseased cells degenerating the body.”
Feeding the Body Right
One of the biggest factor s impacting immune function is simple nutritional
status, something that can be initially addressed with a good
multivitamin/mineral product. “Nutrient status is an important factor
contributing to immune competence,” wrote researchers from the University of
Southampton, England.1 “Undernutrition impairs the immune system,
suppressing immune functions fundamental to host protection. Undernutrition
leading to impairment of immune function can be due to insufficient intake of
energy and macro nutrients and/or due to deficiencies in specific
micronutrients. Often, these occur in combination.” These findings were e
choed by researchers at Cornell University, New York, who noted there is
particular concern about undernutrition in children, which can weaken the immune
response—possibly throughout the course of life.2
“Nutrition authorities have long acknowledged the importance of
macronutrients in maintaining the body’s defenses,” said Marci Clow, MS, RD,
senior director of technical services, Rainbow Light. “Scientists are now also
acknowledging the role micronutrients— vitamins, minerals and related
cofactors—play in the support of the immune system. While eating a healthy
whole food diet does indeed provide many of the vitamins and minerals necessary
for building optimum immune health, the reality is the majority of Americans do
not regularly indulge in a ‘healthy whole food diet’.”
“Marginal nutrient deficiencies in the diet can weaken the immune
system,” Phimister noted. “ These deficiencies do not cause obvious symptoms
of disease, but they can affect mental abilities, coping abilities and the
body’s ability to resist disease and infection.”
Perhaps best-known to consumers in the immune support arsenal is vitamin C.
This antioxidant neutralizes free radicals and regenerates vitamin E, reducing
the burden on leukocytes.3 It also increases production of white
blood cells, levels of antibodies and production of interferon, and assists
functioning of specific immune cells. While there remains some debate about
vitamin C’s ability to prevent the common cold,4 it may help
prevent pneumonia in some populations.5
“Since humans are one of the few animals that do not synthesize vitamin C
in their bodies, it is important to ensure you receive plenty of vitamin C
through diet and nutritional products,” said Angelica Vrablic, Ph.D., manager
of nutrition research at American Health®. “American Health’s Ester- C® is
a good example of an advanced form of vitamin C that is non-acidic, quickly
absorbed due to the presence of metabolites and has a unique chemical structure
that promotes absorption and delays excretion of vitamin C.” Ester-C is made
using a proprietary, water-based manufacturing process that results in a pH
neutral product with naturally-occurring vitamin C metabolites. In vitro work
has found Ester-C can increase the levels of vitamin C within immune cells,6
while an unpublished human trial found subjects receiving Ester-C had increased
vitamin C level s in the body for up to 24 hour s, suggesting the patented form
helps promote absorption and delay excretion of the valuable compound. In
addition, a 2002 study involving 180 British subjects found Ester-C
supplementation could prevent the common cold, as well as limit severe symptoms
and shorten the duration.7
There are several other important vitamins for immune health. Vitamin A,
for example, is required for adaptive immunity and plays a role in the
development of B and Th cells; vitamin A deficiency impairs innate immunity by
impeding regeneration of mucosal barriers and diminishing the function of white
blood cells.8 Another fatsoluble vitamin, vi tamin E, works to
help differentiate T cells in the thymus, inducing higher differentiation for
greater cellular immunity.9 It also appears to improve age-related T
cell signaling10 and NK cel l activity.11 Clinical studies
have found higher levels of serum vitamin E may help maintain immune response
among the elderly,12 and that supplementation (200 IU/d) in elderly
adults could protect against upper respiratory tract infections and reduce the
rate of multiple infections.13
The B vitamins are also important to the health and growth of immune
cells and antibodies. Deficiency of vitamin B6 has been linked to decreased
production of lymphocytes and IL2, a protein cytokine that stimulates the
proliferation of T cells (CD4).14 Folic acid may help increase
proliferation of T cells and their ability to produce cytokines.15
“Scientific data has suggested B-complex deficiencies may occur during chronic
stress as well as depression, and this implication provides an interesting
correlation to the mind/body connection with immune health and overall
well-being,” Cruz added. Minerals also aid immune function.
Selenium is an essential component of thyroid metabolism and
antioxidant defense, as well as immune function. It may improve activation and
proliferation of B- lymphocytes and enhance T-cell function.16 It is
also involved in several key metabolic activities through its selenoprotein
enzymes that protect against oxidative damage.17 Further, selenium
deficiency may allow invading viruses to mutate and cause longer-lasting, more
severe illness.18 Animal research has shown selenium and vitamin E
have synergistic effects, enhancing the body’s response to bacterial19
and parasitic infections.20
Zinc helps to regulate a wide variety of immune system
activities, helping the body fight infections and heal wounds. Severe zinc def
iciencyimpairs immune function; however, studies now show even mild zinc
deficiency may impact immune function by decreasing lymphocyte proliferation and
the secretion of IL-2.21 Thymus atrophy and compromised cell- and
antibody-mediated responses are the “immunological hallmarks” of zinc
deficiency.22
“Typically, individuals seek out zinc as the most needed for immune sys tem
benefits,” said Max Motyka, director, human nutrition, Albion Advanced
Nutrition. “Of course, zinc is a very important component with a wide range of
functions in support of the immune system, playing key roles in many
humoral as well as cell-mediated immune functions.”
Polysaccharides’ Poly-Benefits
Complex carbohydrates also have important roles in immune support. Consider inositol
hexaphosphate (IP6), also known as phytate, a naturally polyphosphorylated
carbohydrate found in beans, grains and other high-fiber foods. It is important
in regulating cellular functions including cell proliferation and
differentiation, and has antioxidant properties. Researchers have noted IP6 may
enhance immune function by reducing cell pro life ration and contributing to
destruction of malignant cells.23 It affects IL-8 secretion and other
neutrophil functions,24 in addition to promoting inflammatory cell
secretions.25
The polysaccharide beta-glucan is found in many dietary supplements as
beta-1,3/1,4 glucans, which occur primarily in grains such as oats and barley,
and beta-1,3/1,6 glucans , primarily derived from yeasts and some varieties of
mushrooms (some of which also contain beta-1,6/1,3 glucans). Betaglucans
activate macrophage activity without over-stimulating cell mediated
immuneresponse.
Yeast-derived beta-glucans (as WGP® 3-6, from Biothera) have been
demonstrated to significantly enhance the immune response. WGP 3-6 is taken up
in the digestive tract and utilized by the body to increase activity of
macrophages and neutrophils.26 Animal research further suggests
administration of WGP 3-6 can enhance recovery after bone marrow injury27
and stimulate macrophages without inducing pro-inflammatory cytokines.28
“An immune priming compound such as WGP 3-6 optimizes the performance of
immune cells,” said Richard Mueller, president and chief executive officer
(CEO), Biothera. “When WGP 3-6 binds to certain white blood cells, it
activates these cells to locate and identify an immune challenge faster and kill
it more effectively. It makes the existing immune cells ‘battle ready’
without stimulation so when they encounter a foreign challenge they more quickly
engage and destroy that challenge.”
Natural beta-glucans and synergistic immune-balancing metabolites produced by
yeast in a patented fermentation process are found in Embria’s ingredient
EpiCor®, which Robinson said works to support mucosal immunity, increase
cytotoxicity of NK cells and inhibit inflammation. “This product helps balance
the immune system and keeps it ‘tuned up’ to give proper immune response
depending on the type of situation,” he said. “EpiCor appears to naturally
‘educate’ the immune system by helping to balance proper immune response.”
Medicinal mushrooms are naturally rich sources of
beta-glucans. “These beneficial mushrooms have been used in the Orient for
hundreds of years,” said Phimister, whose company supplies specialty mushroom
formulas for immune enhancement. “And the immune modulators found in the
beta-glucan molecules in beneficial mushrooms per form three functions: the
inducer component is basic training for the immune system, the antigen-specific
part helps identify critical features of an infectious enemy, and the suppressor
fraction is able to calm the immune system after the ‘enemy’s’ defeat.”
In vitro studies have found maitake (particularly the Dfraction
portion) can decrease activation of B cells and activate helper T cells,
enhancing cellular immunity, while also increasing cytokine production;29
further studies have found D-fraction also activates macrophages and NK
cytotoxicity.30 Dfraction administered to healthy animals has been
found to enhance both innate and adaptive immune function;31 studies
have also found D-fraction increased the survival rate of animals treated with Listeria
monocytogenes by enhancing macrophage function32 and inhibiting
the activity of hepatitis B virus.33
“Maitake is traditionally an adaptogenic herb valued for its reputation to
promote wellness, vitality and longevity,” said Ron Udel l, president, Sof t
Gel Technologies, supplier of Mai take BetaPreme®. “Today, this mushroom is
recognized for its beta-glucan content; our pulverized extracts contain high
levels of immune-supporting beta-glucans and maintain the nutritional profile
and natural fiber content of the original fungus.”
Reishi , called the “mushroom of immortality” in China,
may work by increasing CD4 and T cell counts. Shiitake may activate
macrophages as well as increase IL-1 production, B lymphocyte proliferation and
antibody production. And Agaricus blazei (Himematsutake) may
activate macrophages and neutrophils,34 and increase activity of
cytotoxic T cells.35
“Researchers have observed that Agaricus blazei mushroom modulates the
immune system,” said Yori Takeda, Atlas World USA. “Our Agaricus Bio®
supplies immuno-nutrients such as 1,3- and 1,6-beta-glucans, minerals, vitamins,
amino acids and enzymes to help maintain a healthy immune system and improve
immune response naturally and effectively.”
AHCC ® (Active Hexose Correlated Compound), a proprietary
co-cultivation of organically-grown medicinal mushrooms, has been extensively
studied for its impact on immune function. Its active ingredients include
acetylated alpha-glucan and beta-glucan, and it has an extremely low molecular
weight, which promotes bioavailability.
Recent studies have found AHCC is a “potent immuno-enhancer”, working to
enhance spleen cell proliferation and cytokine production.36 Animal
studies show AHCC can increase survival and clearance of bacteria in a model of
surgical tissue infection;37 it also increases survival and decreases
severity of infection in an influenza model,38 possibly by bolstering
innate immunity and boosting NK activity. AHCC may also function as an
antioxidant.39
Polysaccharides also contribute to the immune support offered by aloe.
A study on a modified Aloe barbadensis polysaccharide (ActiveAloe®, Aloecorp)
found it activated macrophage cells and stimulated fibroblast growth.40
Another component, the carbohydrate fraction acemannan from aloe vera, activates
macrophages and increases the number and function of cy totoxic T cells.41
It appears to activated endritic cells, 42 and increase the
activation capacity of macrophages.43
Larch arabinogalactan (LAG), a mixture of several different
water-soluble poly saccharides with a range of molecular weights, is sourced
from the Western larch (Larix occidentalis). Studies suggest LAG may
enhance several aspect s of immune function including stimulating NK cell
cytotoxicity and inhibiting tumor cell metastasis.44 In addition,
clinical studies using ImmunEnhancer™, from Lonza, found the compound could
increase proliferation of monocytes, and increase serum level s of properdin,
which activates nonspecific immunity.45 Fur ther, the study that
tracked properdin levels found LAG had greater individual effects than and
synergistic abilities with standardized Echinacea extracts, which also contain
arabinogalactans.
Beneficial Botanicals
As mentioned, Echinacea has been studied for its ability to bolster
immune system function, particularly when treating common colds and upper
respiratory tract infections. Echinacea is the genus for several plants,
including E. purpurea, E. angustifolia and E. pallida. It may
activate lymphocytes to scavenge for cellular debris and bacteria, and may
enhance cell-mediated immunity. High concentrations of Echinacea components have
been found to stimulate phagocytic activity, enhancing the release of cytokines.46
It also appears to activate macrophages, stimulating proliferation of cytotoxic
T cells and suppressor T cells.47
In humans, the results have been mixed. A meta-analysis on experimental cold
infection studies reported use of standardized extracts of Echinacea reduced by
half the likelihood of experiencing a clinical cold.48 Two Canadian
trials found Echinacea supplementation reduced symptom severity in subjects who
contracted upper respiratory infections49 or common colds.50
However, a controversial 2005 study found no benefit to 900 mg/d of E.
angustifolia root, administered in three equal doses, to volunteers before
or immediately after a viral challenge;51 herbal experts questioned
the study outcome, given the low dosage and use of an extract of angustifolia
versus purpurea.
Gaia Herbs has been conducting research on Echinacea in studies sponsored by
the National Institutes of Health (NIH) and has made several significant
discoveries. Cruz explained: “We have characterized that the class of
compounds in Echinacea known as alkamides, also known as Rx-A factors, are not
immuno-stimulatory but are immuno-inhibitory and anti-inflammatory. This
discovery may further, and more effectively, explain why Echinacea is effective
during the onset stage of rhinovirus infections. We have also found that
spring-collected aerial portions of Echinacea, when juiced and freeze-dried,
contain a stable group of compounds including arabinogalactan proteins and
polysaccharides (Rx- P factors) that can increase macrophage activity, therefore
improving overall immune efforts.” The company used the research to create two
different immune products with Echinacea—Quick Defense includes Rx-A factors
with black elderberry and andrographis for short-term use during acute
respiratory challenges; Whole Body Defense is designed for long-term support and
combines the Rx- P factors with larch arabinogalactan, maitake and astragalus.
In fact, the Chinese adaptogenic herb astragalus has been
traditionally used for long-term strengthening of the immune system, and its
polysaccharides, flavonoids and saponins have a range of supportive activity.
Astragalus works to increase development of T and B cells, and triggers immune
cells into an active state. It also enhances the body’s production of
immunoglobulin, stimulates macrophages, and helps activate T cells and NK cells.52
Animal studies have shown as t ragalus can increas e macrophage superoxide
production and proliferation of splenocytes.53
Indian Ayurvedic tradition also has strong adaptogens, paticularly ashwagandha
(Withania somnifera), also known as Indian ginseng. Used for more
than 3,000 years in indigenous medical systems for anti-inflammatory and
astringent properties, as well as serving as a liver tonic, ashwagandha is being
studied for a range of immune supportive properties. It may work as an
immunoregulator, stimulating generation of cytotoxic T cells and decreasing
stress-induced immunosuppression. 54,55 Further research suggests it
may inhibit autoimmunerelated inflammation,56 and serveas an
antimicrobial/antifungal.57
“Ashwagandha is an example of a well-studied adaptogen,” said Vladimir
Badmaev, M.D., Ph.D., vice president of scientific and medical affairs, Sabinsa
Corp. “This plant has long been used in Ayurveda as a rejuvenative, especially
useful in conditions characterized by mental exhaustion, anxiety, depression and
chronic disease.”
Similarly, a standardized extract based on the black elderberry,
Sambucol®, has shown benefits as an antiviral and inflammatory modulator.
Studies on patients with influenza have shown Sambucol can significantly reduce
the duration of flu and improve symptoms.58,59 In vitro work using
blood-derived human monocytes further found Sambucol had immuno stimulatory
properties, up-regulating inflammatory and anti-inflammatory cytokine
production.60
Garlic is also reported to stimulate immunity, including
macrophage activity and NK cells, and to increase the production of IL-2, TNF
and interferon-gamma. It is suggested that several bioactive components,
including S-allylcysteine and S-allylmercaptocysteine (formed during extraction
of aged garlic extract [AGE]), contribute to garlic’s immunes timulatig
properties.61, 62 AGE (Kyolic®, from Wakunaga) specifically
maintains homeostasis of immune functions. Studies suggest garlic extract can
inhibit the growth of oral pathogens, including Streptococcus mutans and P.ginigvalis,
63 and antibiotic-resistant pathogens.64,65
Wild oregano , relied upon as a therapeutic herb since
ancient Greek and Roman times, also shows powerful activity against outside
pathogens. Researchers report even minute dilutions of fresh wild oil of oregano
have the ability to sterilize septic water, kill bacteria and halt the growth of
fungi. Further, a blend of wild oregano oils (Oreganol P73, from North American
Herb & Spice) has potent germicidal actions against pathogens including Candida
albicans.
The category of “superfruits” offers several ingredients touted for their
antioxidant and immune-supporting properties. Noni (Morinda citrifolia)
is widely available in the United States and Europe, and the research base is
growing on this Polynesian fruit, which reviewers have found to be pharma
cologically active and toxicologically safe.66 Active constituents
appear to include polysaccharide fractions and glycosides.67 Recent
research has found noni may help inhibit pathogenesis of some types of yeasts,68
and induce vessel degeneration andapoptosis in tumors in vitro.69
Another superfruit, mangosteen (Garcinia mangostana), is known
as the “Queen of Fruits” in Asia; the tropical evergreen tree develops
fruits with a fragrant flesh and deep purple rind, which is what yields the
power fulxanthones and polysaccharides. It appears these compounds have powerful
antibacterial effects, with in vitro activity against a range of
antibiotic-resistant bacteria.70,71 Mangosteen compounds may also
help inhibit IgE-mediated histamine release72 and inhibit development
of preneoplastic lesions.73
“Xanthones have been studied during the last 30 years because these
polyphenols have shown many interesting results in vitro concerning
anti-inflammation and other beneficial properties,” said Wayne G. Geilman,
Ph.D., senior research scientist with Pure Fruit Technologies, which supplies
juice supplements including Mango-xan®. “All the traditional uses of
nutraceutical juices are based on consistent supplementation, and our products
have the potential to serve as immunomodulators.”
Green “superfoods” may also boost immune function. Different preparations
of spirulina, for example, have shown the ability to increase macrophage
activity, stimulate cytokine and antibody production, increase NK cell activity
and activate T and B cells.74 Clinical trials have found
administration of a hot water extract of spirulina enhanced NK cell function,75
while a spirulina-based supplement from Earthrise Nutritionals given to patients
with al lergic rhinit is helped inhibit the production of IL-4, modulating the
Th profile.76 Researchers have also explored specific-fractions of
spirulina. Immolina, a high-molecular-weight polysaccharide fraction, appears to
activate leukocytes and expression of chemokines, while enhancing production of
immunoglobulins and interferon-gamma.77,78 And studies on
phycocyanin, a biliprotein of spirulina, suggests it enhances mucosal immune
function and suppresses allergic IgE antibody response.76
Chlorella, another microalgae, may help normalize immune response
during times of physical stress,80 and aid in immune response to
opportunistic or bacterial infection.81 Canadian researchers reported
the use of a patented chlorella extract (Respondin®, f rom Ocean Nutrition
Canada) enhanced immune response in human subjects by elevating antibody levels
associated with the influenza vaccine.82
Combinations of botanicals may offer synergistic benefits. Triphala, a
traditional Ayurvedic combination of Terminalia chebula, Terminalia belerica and
Emblica officinalis, has a history of use as an internal cleanser,
helping to move out stagnation and improve digestion and nutrient assimilation.
More recent research has focused on its antioxidant properties and ability to
modulate immune function. Animal research found Triphala could prevent
noise-stress-induced alterations in cell-mediated immune response and
antioxidant status,83 possibly by stimulating neutrophil functions.84
Aller-7™ is a proprietary blend of seven standardized herbal extracts from
InterHealth Nutraceuticals. “Aller-7 works by building a healthy immune system
that does not overreact to allergens that can result in respiratory problems,”
said Fiona Taylor, the company’s director of marketing. “It is also
well-tolerated and safe to take on a regular and long-term basis.” In vitro,
in vivo and human clinical studies have shown the extract can stabilize mast
cells85 and promote anti-inflammatory, antioxidant and
anti-anaphylaxis activities.86,87 A three-year, multi-center clinical
trial further reported patients with allergic rhinitis who received Aller-7 had
significant improvements in symptoms, as well as eosinophil count and
mucociliary clearance time.88
Consumers who are looking for immune support are increasingly turning to the
shelves of natural products retailers to bolster their inherent defenses. “The
best way to maintain a healthy immune system is adopting a holistic approach
that includes a healthy diet, exercise, plenty of sleep, stress management and,
as necessary, nutritional supplementation,” Mueller said. “A good
multivitamin is always recommended and then use of products that specifically
enhance immune function.”
As Cheatham concluded, “Building a healthy immune system is certainly
preferable to fighting a disease. The logic parallels the old expression, ‘An
ounce of prevention is worth a pound of cure.’”
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