What About Zinc?

What is Zinc?

Zinc is a metalic mineral (not an herb) present in trace amounts in the human body, animals, and plants. Zinc, as well as other minerals, are needed in very small amounts in order for the body to function properly. Zinc is considered a coenzyme that helps some enzymes work properly.

Enzymes are proteins that initiate chemical reactions in the body. Examples include enzymes that break down fats, proteins, and carbohydrates into smaller substances the body can use for fuel or enzymes can build larger molecules from smaller ones to aid body growth or repair. Enzymes and coenzymes are not used as fuel by the body and do not need to be continuously replenished.

Using an automobile as a crude analogy, enzymes are to the body's fuel as the spark from the spark plug is to gasoline in the engine- without which neither will work.

What does Zinc do?

Severe zinc deficiencies in animals have been demonstrated to decrease growth and food intake as well as suppress immune function. Although zinc is essential to enzyme systems that influence cell division and proliferation its primary function in cell growth is not yet known. 6 It should be noted that zinc does not work in isolation as a number of nutrients have been linked to proper immune system functioning. These include protein/calories, vitamins A, E, and B6 , dietary zinc, copper, selenium, the amino acids glutamine and arginine, and the w-3 fatty acids.

Zinc compounds (not dietary zinc) are used in various preparations including: 3

• Antiperspirants, astringents, corrosives, and mild antiseptics
• Zinc sulfate is used in both eye drop and skin preparations
• Zinc chloride is used in astringent solutions
• Zinc oxide is used in powders, ointments and pastes for skin conditions such as eczema, psoriasis, ringworm, minor bacterial skin infections, itching (calamine) and skin breakdown.
• Zinc pyrithione, in concentrations of 1 to 2%, is used in many commercial shampoos to treat seborrhea and dandruff.

Zinc is present in a wide variety of vegetables and meats. Zinc absorption is higher when form meat sources. Zinc deficiencies should not occur in normal U.S diets.

Who is at risk for a Zinc Deficiency

Persons at risk for zinc deficiency due to inadequate dietary, as well as deficiencies of other vitamins and minerals, include:

• elderly and dehabilitated persons
• extreme fad diets that limit dietary intake of vegetables or meat
• severely calorie limited diets
• more likely in children living in poverty

Zinc supplementation may be required in persons with extremely accelerated metabolic rates such as major burn patients and those undergoing certain cancer treatments.

How much Zinc do I need? 3

Recommended Daily Allowance (RDA) for men is 15 milligrams (mg), for women is 12- 15 mg and for children 1 - 10 years of age is 10 mg.

Is there harm in taking too much Zinc?

Yes, over the long term, taking too much zinc (more than 50 to 100 mg a day) can weaken your immune system, interfere with absorption of other minerals and lower your HDL ("good") cholesterol level.

Can zinc throat lozenges help me get over my cold faster? Zinc lozenges have been aggressively promoted to the public as being effective in treating or lessening the duration of the common cold. Rhinoviruses cause "the common cold".

Frequent symptoms include:

NOTE Fever and severe muscle aches are not part of a common cold in adults. These symptoms, along with the above symptoms, are more suggestive of influenza or a flu-like illness. The effects of zinc on flu were not studied!

Studies on whether zinc lozenges help with the common cold have produced mixed results. Several double blinded placebo controlled studies in 1987 administered zinc lozenges (23 mg) every 2-3 hours in test subjects following rhinovirus inoculation. One study showed zinc gluconate lozenges to lessen the duration of cold symptoms by a few days 5 while two other studies showed no benefit. 2

Likewise, studies in subjects who got their cold naturally have produced conflicting reports. 1 A recent well designed study evaluated over 250 school children meeting criteria for rhinoviral (common) cold and whether zinc gluconate lozenges, 10 mg given 5-6 times daily, decreased the severity and duration of cold symptoms. The study concluded zinc did not have benefit in either reducing severity or duration of cold symptoms. 4 A recent meta-analysis of 8 previous double blind placebo controlled studies did not show zinc lozenges to be beneficial in reducing cold symptoms. 7

If you have a cold and symptoms are bothersome zinc lozenges may be worth a shot. Be aware of possible annoying side effects including nausea and a lingering bad taste in your mouth. You dissolve the lozenges in your mouth. You must stop taking zinc after your cold is finished because of more serious side effects from taking too much zinc over the long run.

Treatment with medications directed at specific symptoms, such as 12 hour nasal sprays for the cough and sore throat due to post nasal drainage, are usually quite effect too. Better yet- see our tips below for avoiding the common cold.

Can I do anything to prevent catching a cold?

Absolutely! By knowing how rhinoviruses cause infection you can greatly decrease your chance of getting a cold even if everyone at work, school, or home has one.

Keep your fingers and hand away from and out of your nose!

When your mother told you picking your nose is a bad habit she was right. An important reason young children get so many colds is they are always touching things and picking their noses.

Rhinoviruses live and multiple in the nose. They get their by hand to nose contact, not by floating in the air as some viruses and bacteria do. When a person with a cold rubs their nose or sneezes into their hand they may place the rhinovirus on any object they touch (utensils, door knobs, etc...). The next person to touch the contaminated object and then touch his/her nose without first washing his/her hands has just seeded their nose with rhinovirus and can possibly expect cold symptoms in the next several days.

People generally must touch their nose on occasion. Hand washing with soap and water before doing so will usually eliminate the rhinovirus from your hand.

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References

1. Antimicrob Agents Chemother 1984 Jan;25(1):20-4 "Reduction in duration of common colds by zinc gluconate lozenges in a double-blind study." Eby GA, Davis DR, Halcomb WW

2. Antimicrob Agents Chemother 1987 Aug;31(8):1183-7 "Two randomized controlled trials of zinc gluconate lozenge therapy of experimentally induced rhinovirus colds." Farr BM, Conner EM, Betts RF, Oleske J, Minnefor A, Gwaltney JM Jr

3. Goodman and Gilman's- The Pharmacological Basis of Therapies 7th edition 1985: 967, 1546

4. JAMA 1998 Jun 24;279(24):1962-7 "Zinc gluconate lozenges for treating the common cold in children: a randomized controlled trial." Macknin ML, Piedmonte M, Calendine C, Janosky J, Wald E Department of Pediatrics and Adolescent Medicine, Cleveland Clinic Foundation, Ohio 44195, USA.

5. J Antimicrob Chemother 1987 Dec;20(6):893-901 "Prophylaxis and treatment of rhinovirus colds with zinc gluconate lozenges." Al-Nakib W, Higgins PG, Barrow I, Batstone G, Tyrrell DA MRC Common Cold Unit, Harvard Hospital, Salisbury, Wiltshire, U.K.

6. J Nutr 2000 May;130(5):1500S-1508S "The Role of Zinc in Growth and Cell Proliferation." MacDonald RS Nutritional Sciences Program, University of Missouri, Columbia, MO 65211.

7. J Nutr 2000 May;130(5):1512S-1515S "Zinc and the Common Cold: A Meta-Analysis Revisited." Jackson JL, Lesho E, Peterson C Department of Medicine-Educational Programs, Bethesda, MD 20814, Department of Primary Care, Internal Medicine Service, U.S. Army Medical Activity, Heidelberg, Germany and. Department of Medicine, Madigan Army Medical Center, Tacoma, WA 98431.

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