Zinc & Immune System Function

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Zinc & Immune System Function JoAnn Guest Jun 27, 2005 19:13 PDT

 

http://www.willner.com/article.aspx?artid=140

 

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 refined 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(8): 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(8): 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.]

 

 

 

 

AIM Barleygreen

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