The unsung antioxidant: Zinc

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Forgetful? Runaway wrinkles? Loss of energy? Sagging skin? Poor circulation? Joints ache? Loss of taste and smell? Old before your time? Free radicals could be the culprit and zinc might be your answer.
WHAT ARE FREE RADICALS?

Free radicals are incomplete, highly unstable, reactive compounds or molecules. Their electron arrangements are out of "spin" balance, like your washing machine when it's weighted on one side. Free radicals are implicated in some 60 killer diseases including arthritis, cancer, heart disease, and premature aging.

Free radicals lead to faulty metabolism of proteins, DNA, and enzymes by oxidizing cells so that they practically rust. Unlike a stable molecule, in which every atom is ringed by pairs of electrons, free radicals carry an unmated electron that desperately wants to pair up with another. By snaring an electron from a neighboring molecule, it can set off a chain reaction that wreaks havoc on cells, disintegrating their membranes and genetic material. If their destructive "rage" is not stopped, free radicals can weaken the whole body causing illness and premature aging. Some researchers in gerontology (the study of aging) believe that free radicals are the most important cause of pathological aging processes.

Free radicals are involved in the formation of crosslinkages, the undesired "links" between protein chains (occurring especially in connective tissues, but also in other tissues). Protein chains give connective tissue their elasticity and strength (similar to the spiral and wires of a spring mattress). When these chains are restricted, they "tie" together, lose their elasticity, and can no longer move freely this is the process known as crosslinking. Reduction of connective tissue elasticity is the most obvious damage. You can easily test this on your hand. Using two fingers, raise the skin on the back of your hand-then release it. Did the skin immediately spring back? If so, it has not yet been aged and damaged by crosslinking. Forehead wrinkles and crows' feet (at the corners of the eyes) are other signs of connective tissue crosslinking.

As we age, more stress is placed on our body and more crosslinkages are produced. As a result, the body's connective tissue becomes more rigid and stiff, with decreased functional capacity. You can see this in wrinkles-the skin is less flexible. But, this is also happening inside your body--blood vessels, muscles, nerve fibers, and tendons are damaged.
WHERE DO FREE RADICALS COME FROM?

For starters, free radicals are by-products of normal cellular metabolism. In order to carry out all of its functions (growth, movement, thinking, etc.), the body requires huge amounts of energy. This energy is produced from the foods we eat and the oxygen we breath. As oxygen is burned for energy, one of its by-products is oxidative free radicals.

Some other source of free radical formation and crosslinkages include:

1. alcohol.
2. tobacco smoke and nicotine,
3. industrial and other emissions.
4. pesticides.
5. pollutants (in our water, food, and air).
6. saturated and overheated fats.
7. smog.
8. certain types of prolonged UV and other radiation.
9. organic solvents.
10. unprotected exposure to sunlight.

Free radicals become highly toxic when the rate of their production exceeds the body's ability to detoxify them.
WHAT CAN WE DO?

So, what can we do about free radicals? First, we can try to avoid anything that promotes free radical formation (see the above list) and, thereby, protect ourselves from the damage they cause.

Second, we can eat raw, toxin-free fruits and vegetables (such as carrots, apples, sweet peppers, and cabbage). In addition, fats should only be consumed as unsaturated fish oils and vegetable oils.

Third, we can supplement our diet with "antioxidants" which are our body's "anti-rust agents." These are the good guys (on white horses) which sweep in, preventing tissue damage by slowing free radical reactions.

Antioxidants not only fight free radicals, slowing the aging process, but also help protect us against some chronic diseases, including allergies, arthritis, cancer, cataracts, and heart disease.

These free-radical scavengers work by sacrificing themselves to prevent oxygen from reacting with other-potentially harmful compounds.
ZINC: THE OTHER ANTIOXIDANT

When we think of antioxidants, we think of vitamins C, E, A (beta carotene), and selenium. But, did you know the essential trace mineral, zinc, is also an important antioxidant?

By 1934, zinc was determined, to be essential for normal growth and development. Zinc is found in every tissue and tissue fluid in the body, and, of the trace minerals, only iron is found in greater concentrations.

Though we have known for some time of zinc's importance in respiration, digestion, growth and development, plus nerve, brain, immune, and vision function, only recently has zinc's antioxidant role in the body been explained. Antioxidants are the front line of defense against free radicals. They have the ability to neutralize free radicals by giving up an electron of their own without becoming harmful themselves, thus putting an end to the destructive chain reaction.

Zinc's action as an antioxidant works in many ways:

First is zinc's vital role in the antioxidant enzyme, superoxide dismutase (SOD). This is probably its most important activity as an antioxidant. SOD is a primary defender against free radicals and is so important to survival that it is the fifth most prevalent protein (of more than 100,000 in the body). SOD eliminates destructive superoxide molecules, a common free radical produced in the body. What's more, a newly released study (1992) indicates that SOD apparently blocks the oxidation of harmful LDL cholesterol, thereby inhibiting the initial stages of atherosclerosis. This offers very promising hope for combating cardiovascular disease.

Second, zinc appears to protect against free radical damage by defending sulfhydryl groups against oxidation. In the body, sulfhydryl groups are a common part of many molecules and are easily oxidized, forming free radicals.

Third, zinc limits free radical production in the body. For example, liver cells produce a free radical known as malondialdehyde (MDA), while human neutrophilis (a type of white blood cell) produce superoxide. These are both decreased by zinc.

Fourth, zinc fights free radicals by competing with prooxidant metals (iron and copper) for cell binding sites. This decreases the possibility of free radical formation.
HOW DO YOU KNOW IF YOU'RE GETTING ENOUGH ZINC?

The RDA for zinc is 15 milligrams per day for men and 12 milligrams per day for women. However, factors such as diet, climate. age, stress. pregnancy, lactation, infection and level of physical activity can all affect individual requirements. If you are following a "healthy" diet eating more fiber, more legumes, vegetables, and whole grains you might not be getting enough zinc. These foods contains oxalates (found in many fruits and vegetables) and phytates (from grains), which may interfere with the absorption of dietary zinc.

Other factors which might affect zinc levels could include an increased calcium intake (widely recommended to prevent osteoporosis) which inhibits zinc absorption. In addition, iron competes with zinc, so if you're taking iron supplements, you might be zinc deficient. Exercise, even moderate physical activity (two to four hours per week) can significantly lower plasma zinc levels. And to top it off, a substantial amount of zinc is lost in perspiration.

One recent study showed that zinc deficiency, coupled with moderate alcohol intake, produced high lipid peroxidation and impaired contraction of heart tissue. Zinc deficiency has also been linked to a reduction in plasma levels of vitamins A, E, and beta carotene.

Further, the tissues of animals deficient in zinc show an increase in free radical production.
SOURCES OF ZINC

Now that we've established your need for zinc, where do you get it? Traditionally, foods have been the main sources for zinc. Unfortunately, most of the foods high in zinc (such as red meat, organ meats, oysters, and nuts) are also high in fat and cholesterol. Most weight-loss programs are very low in red meat. If you are trying to limit your fat intake, you are probably also limiting the above foods, and not getting enough dietary zinc.

In addition, with the magnitude of food additives, food preservatives, radiation, long-term storage, etc., the zinc content of your foods might be grossly reduced.

If you are a vegetarian and don't eat red meat, or if you are trying to increase your fiber intake (which interferes with the absorption of zinc), if you are under stress, or are an athlete, it may not be possible to get the needed zinc through your diet. Almost 90% of the body's zinc is concentrated in the bones arid muscles, and therefore not readily available for other bodily functions. For all these reasons, daily supplementation seems necessary for survival.

But what form of supplements? Zinc supplements are available as zinc sulfate, zinc oxide, and in chelated forms, including zinc citrate, zinc gluconate, and now, zinc monomethionine.

Zinc sulfate and oxide, however, are poorly absorbed. Chelated forms are the most easily absorbed and utilized by the body. According to Robert M. Hackman, Ph.D. (University of Oregon) "New product introductions which include zinc monomethionine may be particularly attractive since the zinc is well absorbed and appears to be effectively delivered to the immune system."

Studies have shown that zinc monomethionine resists dietary fiber, phytate and oxalate. It also offers the additional benefit of providing the amino acid, methionine, another potent antioxidant. Methionine is the most readily absorbed of all the amino acids.
CONCLUSION

Every day, ongoing research reveals something new about zinc and its role in human nutrition. Zinc's value as an antioxidant and free radical scavenger underscores its tremendous importance.

So stick with zinc, the unsung antioxidant, to:

fight those dreaded free, radicals

heal faster

get more enjoyment from the taste of food

have healthier skin and hair

fortify your immune system

reduce the tendency for atherosclerosis

live a healthier, happier, more productive life.
REFERENCES

W.J. Bettger and B.L. O'Dell. A critical physiological role of zinc in the structure and function of biomembranes. Life Sci. 28: 1981: 1425-143 3.

T.M. Bray and W.J. Bettger. The Physiological Role of Zinc as an Antioxidant. Free Radical Biology Medicine 8: 1990: 281-291.

F. Chen, P. Cole, Z. Mi, and L. Xing. Dietary trace elements and esophageal cancer mortality in Shanxi, China. Epidemiology 3 (5): 1992: 402-406.

C. Coudrey, F. Boucher, M.J. Richard, J. Arnaud, J. DeLeiris, and A. Favier. Zinc, deficiency, ethanol, and myocardial ischemia affect lipoperoxidation in rats. Biological Trace Element Research 30: 1991: 103-118.

P.J, Fraker, M.E. Gershwin, It.A. Good, and A.S. Prasad, Interrelationship between zinc and immune function. Fed Proc. 45: 1986: 1474-1479.

Wilhelm Glenk and Sven Neu. Enzyme. Wilhelm Heyne Verlag GmbH & Co., Munich, Germany, 1990.

Darrell J. Graff. "Radioactive isotope Research with Chelated Minerals Chelated Mineral Nutrition in Plants, Animals, and Man. Charles C. Thomas. 1982 pg 277.

C.L. Keen and M.E. Gersliwin. Zinc Deficiency and Immune Function. Annul Rev. Nutr. 10. 1990: 415-431.

H A, Lehr, M. Becker, S.L. Marklund, C. Hubner, K.E. Arfors, A. Kohlschutter, and K. Messmer. Super-oxide dependent stimulation of leukocyte adhesion by oxidatively modified LDL in vivo. Arteriosclerosis and Thrombosis 12 (7): 1992: 824-929.

Richard Passwater, Ph.D. The Antioxidants, Keats Publishing, New Canaan, Conn. 1985.

Richard Passwater Ph.D. The New Superantioxidant Plus, Keats Publishing, 1992.

Carl C Pfeiffer. Zinc and Other MicroNutrients. Pivot Original Health Books, Keats Publishing, 1978. pg 5.

A. S. Prasad. Discovery of human zinc deficiency and studies in an experimental human model. Am. J. Clin. Nutr. 53: 1991: 403-412.

R. Selvum and T.B. Kurien. Restoration of antioxidants in liver by methionine feeding in experimentalrat urolithiasis. Indian J. Biochem. and Biophys. 29 (4): 1992: 364-370.

E.]. Underwood. Zinc. In: Underwood, E.J., ed. Trace Elements in Human and Animal Nutrition. 4th ed. New York: Academic Press; 1977; 196-247.

B.L. Vallee and K.H. Falchuk. The Biochemical Basis of Zinc Physiology. Physiological Reviews 73: (1) 1993: 79-118.

FREE RADICALS CAN DESTROY CELLS BY CAUSING: 1. Accumulation of age pigment. 2. Cross-linking (causing proteins and/or DNA molecules to fuse together). 3. Lipid peroxidation (which causes body fat compounds to turn rancid and release even more free radicals). 4. Lysosome damage (in which free radicals rupture lysosome membranes then invade the cell and digest critical cell compounds). 5. Membrane damage, interfering with the cell's ability to take in nutrients and expel wastes.
POSSIBLE SYMPTOMS OF ZINC DEFICIENCY (IN ADDITION TO FREE RADICAL DAMAGE) INCLUDE:

1. Growth retardation.
2. Skin rashes and lesions.
3. Impaired taste and smell.
4. Delayed wound.
5. Immune deficiencies.
6. Delayed sexual maturation.
7. Night blindness.
8. Low sperm count.
9. Alopecia (hair loss).
10. Impaired reproduction.

These symptoms have been shown to disappear with adequate zinc intake.

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by Dr. Anthony Cichoke

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