Zinc & Immune System Function

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Zinc & Immune System Function

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It is clearly established that adequate supplies of zinc are essential to the

development and maintenance of a healthy immune system and that aging is

associated with immune impairment that can be partially repaired with zinc

supplementation.

 

There are many groups in our population at increase risk of at least marginal

zinc deficiency. We now know that the elderly may be getting insufficient zinc

in their diets.

 

Another problem related to zinc is macular degeneration. " Because this disorder

affect parts of the eyes in which zinc is known to have an important impact on

the metabolic function of enzymes crucial in vision, investigators hypothesized

that zinc deficiencies might play a role in the disease. to test this idea they

constructed a double-blind, placebo-controlled trial involving 151 patients

afflicted by this condition. In a 12 to 24 month follow-up they found that the

patients given zinc supplements had significantly less visual loss than the

group that got placebos. The zinc was given in 100 mg tablets, twice a day with

meals. Side effects were minimal. " (Sheldon Saul Hendler, Md, Phd, The Doctors’

Vitamin & Mineral Encyclopedia, Simon & Shuster)

 

The following study provides another cause for concern about adequate zinc

levels:

 

Zinc deficiency may increase arterial oxidative stress

 

The starting point of this study was the observation that zinc deficiency

severely impairs endothelial cell function, an effect reversed by zinc

supplementation. To determine how zinc affects cytokine production, the

activation of a nuclear transcription factor (NF-kB)was examined in endothelial

cell cultures. NF-kB was chosen because this transcription factor activates

genes directing the synthesis of proinflammatory cytokines and to increased

oxidative stress. Cells deprived of zinc were triggered by tumor necrosis factor

(TNF). TNF signals a cascade of events leading to the synthesis of proteins that

regulate oxidative stress and promote free radicals. Zinc supplementation

reversed the activation by TNF in these cells: zinc inhibited activation of

oxidative stress transcription factors and the synthesis of Interleukin 8 and

promoted a return to homoeostatic balance.

 

Comment: Arteries are vulnerable to ongoing oxidative stress due to exposure to

oxidizing agents such as drugs and free radicals, including superoxide and lipid

peroxyl radicals. Blood contains an elaborate array of antioxidants, including

ascorbic acid, uric acid and defensive serum proteins to limit this damage.

However, antioxidant defenses are not 100% efficient. Zinc participates in these

defenses by serving as a cofactor for the antioxidant enzyme, superoxide

dismutase. Other aspects of zinc Metabolism must be involved, since zinc

deficiency causes profound oxidative damage to proteins, lipids and DNA. As one

example of a nonenzymatic function, zinc is a cell membrane stabilizer. In

addition, this paper shows that zinc deficiency seems to regulate

cytokine-mediated activation of transcription factors, especially those

triggering inflammation and oxidative stress. If zinc deficiency promotes

activation of oxidative stress and inflammatory cytokines by endothelial cells,

then

zinc status may be important in the development of atherosclerosis. Zinc is

removed by food processing and subclinical deficiencies are-likely with

compromised diets.

 

Connell P et al. Zinc attenuates tumor necrosis factor-mediated activation of

transcription factors in endothelial cells. J Am College Nutr 1997; 16: 411-417.

 

To provide more information on zinc, we are excerpting an article from the

magazine, Health & Nutrition Breakthroughs, published by New Hope Natural Media,

written by Dr. Michael Janson:

 

Zinc— Immune System’s Missing Link?

 

by Michael Janson, M.D.

 

To the general public, minerals are far less understood or valued than vita

mins, though both are equally important to physiological functions. Among

minerals themselves, calcium, magnesium and iron receive a disproportionate

amount of attention, even though other minerals are equally necessary. Actually,

all nutrients work in concert in our tissues to keep us healthy. One may well

wonder, therefore, why some minerals are held in so much higher esteem than

others. Well, calcium’s popularity, for example, is due largely to advertising

by the dairy industry to underscore the importance of milk, and iron is well

known because its deficiencies are so easy to detect.

 

Mineral nutrients can be found in varying quantities in both our diets and our

bodies. When they are present in our bodies in large amounts (measured in

grams), they’re called major minerals and include calcium, chlorine, magnesium,

phosphorus, potassium, sodium and sulfur. Those that occur in smaller quantities

(measured in milligrams or micrograms) are called trace minerals and include

boron, chromium, cobalt, copper, iodine, iron, manganese, selenium, silicon and

zinc. Deficiencies of either major or trace minerals can be as devastating to

one’s health as a lack of other better-known nutrients such as vitamins A, C, E

and B complex. .

 

A Zinc Deficiency Can Be Devastating to Overall Health

 

Though zinc gets little attention, it is critical to a healthy body. Without it,

more than 300 enzymes including trypsin and alcohol dehydrogenase cannot work

properly, and physiological functions such as digestion and alcohol metabolism

break down. The human body generally contains 1.4 g to 2.5 g of zinc.1 Much of

this zinc is found in muscle and bone. It is also present in skin, hair and

nails, as well as in the retina of the eye and in the prostate gland.

 

One of zinc’s most essential roles is for the white blood cells of the immune

system, where it helps the body fight off a range of viral infections—from strep

and influenza to herpes and the common cold. Some white blood cells produce

antibodies (humoral immunity), while others are phagocytes that attack and

destroy invaders, thereby providing cellular immunity.

 

The thymus gland, located just under the sternum, controls some of our immune

functions and is affected by the amount of zinc in the body. For instance, the

thymus produces thymulin, a thymic peptide that is responsible for cell-mediated

immunity. As we age, the thymus gland diminishes in function and size-from

nearly the same size as the heart in infants to almost undetectable in elderly

people. This happens in both humans and animals. Although long considered a

normal process, it appears related to zinc nutritional status. A zinc supplement

given to aging mice restored the function of their thymus glands and led to the

glands’ regrowth.2 Researchers thus concluded that the usual involution of the

thymus gland is not inevitable and can be reversed with zinc supplements.

 

Thymus-derived cells (T-cells) andnatural killer cells likewise depend on zinc.

Both T-cells and natural killer cells support a variety of immune-system

functions such as destroying foreign cells, vitally infected cells and cancer

cells. An in vitro study showed that zinc increased the response of T-cells to

all immune stimuli by 100 percent.3 The authors concluded that " treatment with

zinc may have immunotherapeutic relevance, particularly in the aged and stressed

organism. "

 

Zinc has been linked to the body’s ability to resist viruses, especially

respiratory infections.4 In a group of malnourished children in Ecuador,

supplementation with zinc significantly reduced the incidence of cough, fever

and respiratory secretions compared to placebo. However, after supplementation

ceased, the symptoms returned to previous levels. In addition, two Italian

doctors concluded that zinc deficiencies in elderly people may lead to

depression of both humoral and cellular immunity, a significant increase of

susceptibility to infections, and an increase in morbidity and mortality.5

 

Zinc deficiency is often the result of a poor diet-it is one of the hallmarks of

malnourishment-but it can also be caused by poor intestinal absorption or

excessive zinc loss resulting from trauma, bums, stress, bleeding, diabetes or

chelation therapy (proper protocol for chelation includes zinc supplements). It

is difficult to evaluate the body’s level of zinc because no single laboratory

test is ideal. Physicians must therefore rely on the signs and symptoms of zinc

deficiency as well as lab tests.

 

Supplementing with zinc is quite safeits only significant side effect is lowered

copper levels in the body tissues, since the two minerals compete for

absorption. Considering zinc’s safety, people should consider taking zinc

supplements, especially as they age-being sure to include copper in the proper

balance. Most practitioners who supplement their patients’ diets with zinc also

recommend taking copper at a ratio of 10 mg to 15 mg zinc for each milligram of

copper.

 

Zinc And The Common Cold

 

Despite research showing that zinc improves immunity, clinicians still don’t

know for certain if zinc supplements can help treat a common cold in people who

are not grossly malnourished. (Studies on malnourished people may not accurately

reflect how supplements affect a healthy person.) A number of studies, however,

suggest that supplementation can help.

 

A 1989 in vitro study showed that zinc chloride can inhibit growth of

rhinoviruses, which along with coronaviruses and adenoviruses are responsible

for most colds.6 A 1984 clinical trial demonstrated that the duration of colds

was cut in half in the subjects taking zinc (23 mg every two hours) compared to

those taking a placebo.7 After seven days, 86 percent of the zinc group were

free of symptoms, compared to only 46 percent of the placebo group. In a 1987

clinical study, it was shown that zinc gluconate lozenges reduced the symptom

score from 8.2 to 5.7 (a 30 percent reduction) in subjects. who developed upper

respiratory infections after being exposed to an infecting dose of rhinovirus.8

 

However, several investigators in early controlled studies did not find zinc

helpful for treating colds.9,10 They suggested that the controls in previous

studies (other than the ones mentioned above) were inadequate because the ,

intensely bitter taste of zinc would have made blinding difficult. The

researchers also described side effects in the zinc-treated groups, but these

were mainly due to the taste of the zinc leading to nausea and temporarily

altered taste buds. I I

 

Yet even in this purportedly negative study, the authors admitted that the

zinctreated group had reduced symptom severity-a statistically significant 7

percent to 9 percent. The dose of zinc and the specific zinc compounds used

varied from study to study, and this may account for the discrepancies.

 

Most recently, researchers demonstrated a significant reduction in cold symptoms

in a group of 50 patients given zinc gluconate lozenges compared to a placebo

group of 50 controls.12 The colds were significantly shorter in the zinc group

than in the placebo group (4.4 days versus 7.6 days). The zinc group also had

significantly fewer days of coughing, headache, hoarseness, nasal congestion,

nasal drainage and sore throat. Recognizing that zinc lozenges apparently do

help treat viral respiratory infections, other researchers attempted to identify

some of the mechanisms at work, concluding that the interruption of viral

binding sites was most likely a factor.13

 

Supplements That Are Easy To Swallow

 

One problem associated with zinc is no longer an issue-its bitter taste is

easily masked in lozenge-type supplements. The supportive research cited

suggests that lozenges are worth taking at the onset of a cold because of their

potential to help treat viral upper respiratory infections. But zinc itself is

by no means a cure-all nor an isolated magic bullet. Zinc supplements are best

considered as part of a comprehensive immune-enhancing program that includes

other nutrients such as vitamins A, B6, C and E. Essential fatty acids and

Co-Q10 are also important to a healthy immune system and should be taken

routinely. Immune stimulating herbs such as Echinacea angustifolia or E.

purpurea and Oregon graperoot (Mahonia aquifolium) also help build immunity and

reduce the symptoms of respiratory infection. Add a whole-foods diet low in

sugar (sugar inhibits white cell function), regular exercise and a stress

-management program and you have a true prescription for a strong immune system.

 

Michael Janson, M.D., is president of the American Preventive Medical Associ .

ati . on and a fellow and president-elect of the American College for

Advancement in Medicine. Janson is the author of The Vitamin Revolution in

Health Care. He practices nutrition therapy, chelation therapy and preventive

medicine at the Center for Preventive Medicine in Barnstable, Mass.

 

REFERENCES

 

1. Under, M. ed. Nutritional Biochemistry and Metabolism New York: Elsevier

Science Publishing 1991.

 

2. Mocchegiani, E., et. al aL Reversibility of the thymic involution and of

age-related peripheral immune dys functions by zinc upplementation in old mice. "

Int J Immunopharmacol 17(9): 703-18, September 1995. Saba, A.R_ et at. " Zinc

induces thymulin secretion from human thymic epithelial cells in vitro and

augments splenocyte and thymocyte responses in vivo. " Int J Immunopharmacol

17(9): 729-33, September 1995.

 

4. Sempertegui, F, et at. " Effects of short-term zinc sup, plementation cm

cellular immunity, respiratory symptoms and growth of malnourished Equadorian

children 1~ Eur J Clin Nutr 50(1): 42-46, January I

 

5 Ripa, S. & Ripa, R., " Zinc and the elderly. " Minerva Med 1995, (6): 275-8,

June 1995.

 

6. Merluzzi, %’J., et at. " Evaluation of zinc complexes on replication of

rhinovirus 2 in vitro. " Res Commim Chem Pathol Pharmacol 66(3):425-40, December

1989.

 

7 Eby, G.A., et

 

in duration of common

 

cold, by zinc gluconate lozenges in a double-blind study. " Antimicrob Agents Che

25(l): 20-24, January 1984.

 

8. Al-Nak ib, W, et al. " Prophylaxis and treatment of rhino virus colds with

zinc gluconate lozenges. " J. anamicrob Chemother 20(6):893,901, December 1987.

 

9. Douglas’ R.M., " Failure of effervescent zinc acetate lozenges to alter the

course of upper respiratory tract infection., in Australian adult,.- Antimicrob

Agents Chemother 31(: 1263-65, August 1987.

 

10. Fair, B.M., et al. " Two randomized controlled trials of zinc gluconate

lozenge therapy of experimentally induced hin.,i... colds. " Antimicrob Agents

Chemother, 31(: 1183-87, August 1987.

 

11. Smith, D.S., et al. " Failure of zinc gluconate in treatment of acute upper

respiratory tract infection,. " Antimicrob Agents chemother, 33 (5): 646-48, May

1989.

 

12. Mossad S.B., et al. " Zinc gluconate lozenges for treat, ing the common cold.

A randomized, double-blind placebocontrolled study. " Ann Intern Med 15;125(2):

81-88. July 1996.

 

13.Novick, S G., t al. " How does zinc modify the com- cold! Clinical

observations and implications regarding mechanisms of action. " Med Hypotheses

46(3): 295-302, March 1996.

 

[excerpted from Health & Nutrition Breakthroughs, December 1997, New Hope

Natural Media. (303) 939-8440.]

 

 

 

 

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