The immune
system is an intricate and complex defense system that functions to protect the
body from foreign pathogens that seek to invade and cause harm to the body.
Although the immune system is able to defend and destroy the majority of
foreign invaders, there are some pathogens that are able to evade the immune
response and penetrate the defense system. Therefore, in order to compensate
for the immune systems’ flaws, there are alternative measures that can be taken
to aid the immune response. Additional measures include the use of
supplementary dietary ingredients which can be utilized to enhance the immune
response and serve as an added protection in cases of a weakened immune system
or sneaky invaders. There are various dietary ingredients that contain
properties that are useful in boosting the immune response. Dietary ingredients
are defined as “a vitamin, a mineral, an herb or other botanical, an amino
acid, a dietary substance for use by man to supplement the diet by increasing
the total daily intake, or a concentrate, metabolite, constituent, extract, or
combinations of these ingredients” (Kalra, 2003). Therefore, dietary
ingredients encompass a wide spectrum of supplements that have the capability
of producing a positive impact on the immune system’s response. Although there
are many dietary ingredients that can be used to produce effects on the immune
response, some ingredients that are recognized as having a particular impact on
the immune system include Echinacea
and Ginseng.

Herbs

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                        The use of herbal therapy or phytomedicine has been
a long standing practice that has been thought to have the power to bring about
healing capabilities (Block & Mead, 2003). This method has gained momentum in
modern medicine as a form of complementary medicine (Block & Mead, 2003).
Among some of the herbal agents that are used to stimulate the body’s disease
fighting mechanisms, Echinacea and Ginseng are the most widely used (Block & Mead, 2003). Herbal
remedies that bring about effects on the immune system are classified as either
adaptogens or immunostimulants. Adaptogens are defined as “substances that are
reputed to increase the body’s resistance to physical, chemical, and biological
stressors” (Block & Mead, 2003). On the other hand, immunostimulants “are
agents that activate the body’s nonspecific defense mechanisms against
infectious organisms (notably viral and bacterial pathogens) or against
neoplastic cells” (Block & Mead, 2003).  The purpose of immunotherapy is primarily to
activate immunologic cell activity that interact directly with infectious
agents or neoplastic cells (Block & Mead, 2003). It is believed that herbal
immunostimulants may “help rectify the moderately compromised cell-mediated
immune response”, but have only a slight impact on the normal immune response (Block
& Mead, 2003). Most herbal agents have been found to enhance innate
immunity, which is the first line of defense that is not intrinsically affected
by prior contact with an antigen. Herbal agents have been found to produce
effects on cell-mediated immunity by producing changes in the “natural killer
(NK) cell number and activity, lymphokine-activated killer (LAK) cell activity,
macrophage activity, phagocytic activity, and proliferation of specific
T-lymphocytes subsets” (Block & Mead, 2003). It has also been found that
herbal agents also seem to have an effect on acquired immunity (Block &
Mead, 2003). Herbal agents have been found to produce effects on acquired
immunity by producing changes in “mitogenic effects on B lymphocytes (increased
proliferation) and production of specific types of antibodies” (Block &
Mead, 2003). There is evidence that suggests herbal agents have the ability to
manipulate the natural immune mechanisms to inhibit the progression and
development of some neoplastic and infectious diseases (Block & Mead, 2003).
Herbal supplements can also be used as a complement to cancer treatments because
of their immune stimulating capabilities. Herbal supplements for cancer
patients may have the potential to protect cancer patients from contracting
illnesses such as community-acquired respiratory viruses when their immune
system is weakened from chemotherapy (Block & Mead, 2003). Therefore, herbal
agents are of strong relevance to the overall health and survival of
immunocompromised patients (Block & Mead, 2003).

Echinacea

                        Some
of the more widely used herbal immunostimulants lie under the genus, Echinacea (Block & Mead, 2003). The three
species that are commonly used for medicinal purposes include: Echinacea purpurea, Echinacea angustifolia, and Echinacea
pallida (Block & Mead, 2003). The herb is native to North America,
where Native Americans were the first to discover its’ healing qualities and
then echinacea was later used by the white colonists (Block & Mead, 2003). Echinacea is commonly known as a “cold fighter”
because of its’ effectiveness against upper respiratory infections (Block &
Mead, 2003). However, it can also be useful in the treatment of “infections
with Candida albicans and Listeria monocytogenes, chronic pelvic
infections, chronic fatigue syndrome, herpes infections, cancer, chronic
arthritis, and a variety of skin diseases, wounds, and ulcers” (Block &
Mead, 2003). Although echinacea has
been found to contain useful healing properties, the three species contain a
variety of phytochemicals that are difficult to prepare and produce the same
results consistently (Block & Mead, 2003). This lack of understanding about
the chemical mechanisms of echinacea will
continue to limit the accuracy of treating specific medical conditions (Block
& Mead, 2003). However, it is claimed that echinacea produces effects on
the immune system by enhancing “phagocytic activity, macrophage activation, and
NK cell activity” (Block & Mead, 2003). The echinacea constituents reported
to produce immunologic effects include: polysaccharides, glycoproteins,
alkamides, and cichoric acid (Block & Mead, 2003). It was found that E. purpurea purified polysaccharides
“induce macrophage activation and increase phagocytic activity in vitro and in
vivo in mice” (Block & Mead, 2003). Increased immune function suggests that
the immune effects “could be mediated by increased monocyte secretion of
several cytokine, including tumor necrosis factor-alpha as well as interleukins
1, 6, and 10” (Block & Mead, 2003). In some preclinical trials, E. angustifolia was found to inhibit
“the infiltration of inflammatory leukocytes and reduced edema” (Block &
Mead, 2003). E. purpurea produced
effects that increased the number of NK cells significantly and stimulated “the
classical and alternative pathways of complement activation” (Block & Mead,
2003). Treatments with E. angustifolia
produced an increase in the antibody, immunoglobulin G (IgG) (Block & Mead,
2003). These findings suggest that echinacea’s primary mechanism may be its’ effects on cell-mediated immunity (Block
& Mead, 2003). Echinacea usage for cancer patients prior to chemotherapy in
one clinical trial resulted in a dramatic increase in leukocyte number two
weeks after chemotherapy was administered (Block & Mead, 2003). However, it
was observed that there was “no impact on phagocytic activity or lymphocyte
subpopulations” (Block & Mead, 2003). E.
purpurea may be best known for its’ popularity in reducing the symptoms of
upper respiratory tract infections (Block & Mead, 2003). E. purpurea fluid extracts are most
commonly used in the treatment of upper respiratory infections, but its
effectiveness is still inconclusive (Block & Mead, 2003). Even though the
clinical trials that have been run to test the effectiveness of Echinacea have
been modest in quality, it can be concluded that there is evidence that
Echinacea is effective for treating URIs (Block & Mead, 2003). Some of the
many immunomodulatory benefits that have been cited include “phagocytic
leukocyte and NK cell activation, macrophage activation, and changes in number
and activity of T- and B-cell leukocytes” (Block & Mead, 2003). 

Ginseng

                        Ginseng
is another type of herb that is a dominant amongst the wide variety of herbs
used in phytomedicine. Ginseng “is a slow-growing root herb that has been used
medicinally for more than 3000 years by practitioners of traditional Chinese
medicine” (Block & Mead, 2003). Ginseng is highly regarded and researched
in Asia and is regarded as an adaptogen and an immunostimulant (Block &
Mead, 2003). There are three commonly used species that are referred to as
ginseng, they include: Panax ginseng,
Panax quinquefolius, and Eleutherococcus senticosus (Block &
Mead, 2003). Panax ginseng is the
predominant and the most well researched ginseng species. The main immune
mechanisms of P. ginseng include:
“immunostimulation, increased antitumor activity, improved cardiovascular
function (vasodilation, and reduced platelet aggregation), antioxidant activity
(increased oxygen radical scavenging and decreased lipid peroxidation),
hypoglycemic activity, and stimulation of the pituitary-adrenocortical system
(steroidal effect)” (Block & Mead, 2003). Ginseng’s main active components
are “glycosidal saponins (glycosylated steroids) known as ginsenosides” (Block
& Mead, 2003). Ginsenosides can act as protectors of the cell’s outer
membranes, much like antioxidants, mainly for immune and nerve cells (Block
& Mead, 2003). In laboratory and human studies, antioxidant micronutrients
have been shown to enhance immune function (Block & Mead, 2003). It was
discovered that ginseng in vitro, stimulated macrophage activation to initiate
the production of reactive nitrogen intermediates in order to attack and kill
tumors (Block & Mead, 2003). In athymic rats, it was found that ginseng
increased resistance against Pseudomonas
aeruginosa pneumonia which is “virtually impossible to treat with
antibiotics” and caused changes in IgM, lung IL-4, IFN-?, and TNF-? (Block
& Mead, 2003). There are also differences between extracts of wild Panax ginseng and cultured Panax ginseng (Block & Mead, 2003).  Research indicates that wild Panax ginseng stimulated lymphocyte
production in vitro whereas cultured Panax
ginseng did not (Block & Mead, 2003). In other experiments, the flu
vaccine was given to participants followed by Ginseng treatment. This method resulted in “a highly significant
reduction” of the frequency of upper respiratory infections (Block & Mead, 2003).
In the same experiment, it was also reported that NK activity “was twice as
high as the placebo group” (Block & Mead, 2003). Ginseng is also a
promising complementary treatment to chemotherapy. In one experiment, Shenmai
(herbal combination containing ginseng), in addition to chemotherapy “resulted
in significantly increased T-cell and NK levels; a trend toward increased
T-helper/T-suppressor ratios was also reported” (Block & Mead, 2003).

Conclusion

                        The
dietary ingredients Echinacea and Ginseng are some of the most well-known and studied
dietary ingredients that serve to boost the immune response. Echinacea has been
reported to contain particularly valuable properties for treating upper
respiratory infections. On the other hand, Ginseng is known as the “heal all”
tonic. Ginseng has been shown to reduce the frequency of respiratory
infections, has shown promise in acting as a complementary treatment for
cancer, and has been reported to increase T-cell and NK levels. All of which
stimulate the immune response and lead to the eradication of the invading
pathogens from the body.