From the September 1999 Nutrition Science News
by David Wolfson, N.D.
Supplements shore up defenses during cold and flu season
The human body is continually protecting itself from the outside
world. To shield itself from harmful environmental stimuli, the
body employs its cells, biochemicals, organs and tissues. The
complex interaction of these physiological systems produces
immunity. Some of these systems have dual roles: The digestive
system, for example, not only extracts and absorbs nutrients from
foods but also destroys pathogenic organisms that may be present
in foods. Other immune system components are more focused: White
blood cells are specifically designed to destroy invading
One of the immune system's more extraordinary features is its
ability to respond to the environment. When a threat is
encountered, the immune system can mount an attack specifically
designed to neutralize it. This is demonstrated most clearly in
the antigen-antibody interaction. Antigens are proteinlike
substances that identify living matter, much like biochemical
name tags. When a white blood cell encounters another living
organism--a bacterium, virus or normal human cell--it checks the
name tag. When the system is working properly, if the tag says
anything other than "self," the white blood cell considers the
organism a hostile invader. Other immune cells are alerted and
information gleaned from the antigen is used to design antibodies
precisely configured to destroy both the antigen and the organism
that carried it into the body.
Defects in any of the components of the immune system can impair
its ability to recognize and neutralize invading organisms and
thus increase susceptibility to infectious disease.
How can immune systems be kept at peak operating efficiency? An
important clue is contained in the work of Weston Price, D.D.S.,
a researcher who, almost 60 years ago, observed a high degree of
immunity among native cultures he encountered as he traveled the
world. Price described cultures free from tuberculosis (one of
the most prevalent infections in his time), dental disease,
cancer and arthritis in locations including Africa, the Andes
Mountains, Melanesia and New Zealand. These highly resistant
peoples invariably ate whole, unprocessed foods and were
physically active. Price observed that when individuals from such
cultures relocated to areas where refined and processed foods
were prevalent, they began to contract infectious and
degenerative diseases. Upon returning to their native villages
their health and immune status recovered. 
Modern research supports Price's observations. Many studies show
that immune function depends on nutrients found primarily in
whole, unprocessed foods.  Researchers have also
confirmed that physical activity and a healthy emotional state
are essential for proper immune function. [3,4]
A healthy diet and lifestyle may be the cornerstones of a strong
immune system, but what specific measures can be taken when a
person is faced with an immune challenge such as the annual cold
and flu season?
Nutrients for Immune Support
Fortunately, a wide variety of immune-enhancing nutritional and
herbal supplements is available.
]I recommend 200400 IU daily
and up to 800 IU at the first sign of infection. [13-15]
Co-Q10 is one nutrient that often goes unrecognized as an
immune-system supporter. Immune cells divide more rapidly than
most cells and are in constant need of repair and maintenance.
All of this work requires energy, and Co-Q10 is a critical factor
in energy production pathways. In both animal and human studies
Co-Q10 has compensated for immune deficiencies caused by aging or
disease. [5,6] One study showed Co-Q10 significantly
improved immune function and reduced symptoms in a number of
HIV-infected individuals.  Daily Co-Q10 doses range
from 20 to 200 mg. I recommend 10 mg twice daily for maintenance,
increasing to higher doses during an infection.
Vitamin A as retinol or beta-carotene is a recognized
immune-supportive nutrient. Almost a dozen studies demonstrate
vitamin A's ability to reduce the incidence and severity of
infectious illnesses. [8,9] Vitamin A supports immunity
by maintaining the integrity of the body's mucosal surfaces.
Mucous membranes such as those of the respiratory and
gastrointestinal tracts act as natural barriers to pathogens.
Vitamin A also improves antibody responses and increases white
blood cell proliferation. Adding 10,000-15,000 IU per day of
vitamin A, or 25,000 IU of mixed carotenoids, to a healthy diet
can help boost immune response. Up to 100,000 IU per day can
usually be taken safely on a short-term basis. [10
]Pregnant women and people with liver conditions, however,
should always consult a health care provider before supplementing
with vitamin A. In its retinol form, vitamin A has the potential
to cause birth defects and liver toxicity.
Vitamin C is the most widely known immune-stimulating
nutrient. Numerous studies show that vitamin C, also known as
ascorbic acid, works on several levels to support immune
function. In addition to enhancing the activity of immune cells,
vitamin C acts as a cofactor in the production of collagen, the
principal protein found in all connective tissues. By helping
maintain the strength and integrity of connective tissue
structures, vitamin C keeps infections from spreading throughout
the body. 
I recommend 1 g of vitamin C daily as a preventive measure.
Customers should increase their dose at the first sign of a cold,
flu or other illness but should not exceed 10 g daily unless they
are advised to do so by a health care
Vitamin E is present in higher concentrations in immune
cells than in any other cells of the body. Interestingly, white
blood cells often use free radicals to help destroy pathogenic
organisms. The high concentrations of antioxidant nutrients,
including vitamin E, allow the white blood cells to use the
destructive power of free radicals without being harmed. Studies
show that people with lower serum levels of vitamin E are
significantly more susceptible to infection than those with
higher levels  and that supplemental vitamin E can
improve immune responses in both sick and healthy
Zinc accelerates the growth of immune cells while
inhibiting the replication of the cold-causing
rhinoviruses.  Zinc also helps maintain the health of
the thymus gland and improves the function of lymphocytes and
phagocytic immune cells, all of which are vital to immune system
function. [17,18] Clinical trials confirm zinc's
usefulness in combating infectious disease. In one study, zinc
gluconate lozenges were tested against placebo in a group of 100
patients with cold symptoms. Each zinc lozenge contained 13.3 mg
of elemental zinc. Patients took one lozenge every two hours
while awake. Those in the zinc group experienced significantly
less coughing, headaches, nasal congestion, hoarseness and sore
throats than the placebo group. Side effects were minimal--mostly
harmless reactions to the taste of the lozenge. 
These positive effects of zinc in adults have not been proven in
Zinc supplementation can range from 15 mg daily for prevention to
100 mg daily for acute infections. If a cold is accompanied by a
sore throat, recommend zinc lozenges. These are usually more
effective because they bring the zinc in direct contact with oral
mucosa. One cautionary note: Taking high doses of any mineral
long-term can cause other mineral imbalances and zinc is no
exception. A zinc-copper imbalance can be particularly
problematic--several studies suggest that high levels of zinc
relative to copper may promote atherosclerosis and increase
mortality due to coronary artery disease. 
Probiotic microorganisms, although technically not
nutrients, are nonetheless important to immune function.
Lactobacillus and bifidobacteria species have been shown to
increase numbers of circulating lymphocytes, 
stimulate phagocytic activity of white blood cells, 
elevate antibody responses  and increase production
of immune-modulating chemicals such as gamma
interferon.  I recommend probiotic products that also
contain a prebiotic such as fructooligosaccharides (FOS).
FOS are carbohydrates that support the growth of probiotic
organisms in the gastrointestinal tract. A recent study in
Lancet showed that oligosaccharide molecules can bind to
pathogenic microbes, thereby preventing their attachment to host
cells.  For immune support, direct your customers to
refrigerated probiotic products that contain 3 billion to 4
billion organisms per gram. For maintenance I recommend 1 g
either several times a week or daily. For therapeutic purposes,
increase the dose to 1 g three times daily.
Herbs for Immune Support
Herbal medicines have been used throughout history to enhance
human resistance to disease. Modern herb research and new
understanding of the immune system have explained many mechanisms
by which these herbs work.
Echinacea (Echinacea spp.), one of the most widely
known immune-supporting herbs, exerts some direct antimicrobial
action but primarily boosts immune-cell activity and prevents
bacterial enzymes from breaking down the body's
tissues. [26,27] Clinical trial results are mixed, some
showing little or no activity,  others demonstrating
a marked ability to reduce cold symptoms.  (For more
on echinacea, see "Doctor's Insight" on page 411.)
Prescription for Wellness
Dr. Wolfson recommends the following natural immune enhancers to
ready your customers for the cold and flu season.
Co-Q10 10 mg twice daily; 50-100 mg twice daily during
Probiotics with FOS 4 billion organisms/day; 4 billion
organisms three times/day during illness
Vitamin A 10,000-15,000 IU/day (or 25,000 IU mixed
carotenoids); 100,000 IU/day during short-term illness*
Vitamin C 1 g/day; up to 10 g/day during illness
Vitamin E 200-400 IU/day; 800 IU during illness
Zinc 15 mg/day; 100 mg/day during illness, lozenges for
*Pregnant women and people with liver conditions should always
con- sult their health care provider before supplementing with
At the first signs of a cold or flu, several 1-mL droppers of
echinacea tincture taken every two to three hours may help abort
the illness. During the course of an infection, a similar dose
can be taken at less frequent intervals. Standardized echinacea
formulations should be taken according to package directions.
Berberine-containing herbs have long been used for their
antibiotic action and toning effects on the respiratory tract.
Barberry (Berberis vulgaris), goldenseal (Hydrastis canadensis)
and Oregon grape (Berberis aquifolium) all contain the
antimicrobial phytochemical berberine.
Studies confirm berberine's antimicrobial activity against a wide
variety of bacterial, fungal and parasitic species. 
In one study berberine was shown to block streptococci from
adhering to epithelial cells, the type of cell found lining the
respiratory passages.  This suggests
berberine-containing herbs may be particularly useful in strep
infections. Other studies have shown the compound has a
protective effect on thymus gland cells  and supports
other immune cells.  Any of the berberine-containing
herbs can be taken on their own, or with echinacea and other
immune-supportive herbs. All berberine-containing herbs should be
avoided during pregnancy because they may cause premature uterine
Garlic (Allium sativum) has more lore surrounding
its ability to fight illness than any other herb. In vitro and
animal testing seem to support garlic's use as a broad-spectrum
antimicrobial, [33,34] but there are few human clinical
trials. Epidemiological evidence suggests garlic may reduce the
incidence of certain types of cancer,  but whether
this is the result of improved immune function is not clear. It
seems prudent to include garlic in the diet on a regular basis as
a preventive measure and to increase its consumption, either
fresh or in extract form, during cold and flu season.
Other herbs are also reported to have either antimicrobial
or immune-enhancing effects. Licorice (Glycyrrhiza glabra), St.
John's wort (Hypericum perforatum) and Lomatium (Lomatium
dissectum) seem particularly suited for treating viral
infections. All three have demonstrated virucidal activity in
vitro. [36,37] Licorice has also been shown to increase
the activity of macrophages and natural killer cells--critical
elements of the immune system. People with high
blood pressure, however, should consult a health care
practitioner before using licorice. Astragalus (Astragalus
membranaceus), ginseng (Panax ginseng), and several species of
mushroom including shiitake (Lentinus edodes), reishi (Ganoderma
ludidum) and maitake (Grifolia frondosa) have been used
historically to increase resistance. Astragalus enhances T cell
function.  Panax ginseng has been shown to increase
numbers and activity of lymphocytes, neutrophils and T
cells.  And shiitake, reishi and maitake mushrooms
all contain polysaccharide and protein complexes that stimulate
immune cells and their ability to produce antimicrobial
substances.  All of these medicinal plants can be
taken alone or in combination with other immune-supportive
Immune health is ultimately our last defense against
disease-causing organisms. The antibiotics upon which we have
grown so dependent do nothing to support our own resistance and
in fact have created antibiotic-resistant organisms. If we are to
maintain our ability to ward off harmful environmental organisms
we must shift our focus from reliance on drugs to enhancing our
David Wolfson, N.D., is a naturopathic physician, nutrition
educator, and writer as well as a consultant to the natural
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