Zinc

 

Zinc Introduction

The trace element zinc may be one of the most important minerals consumed in the human diet. Being responsible for approximately 100 - 300 various chemical processes in our biological systems, this particular essential mineral is one we cannot live without. [1] Zinc serves primarily as a co-factor to an estimated 60 plus different enzymatic activities, taking place in our bodies on a daily basis. Many of these enzymes directly coincide with our body’s ability to metabolize all nutrients consumed via dietary foods.

Studies have shown that the human body contains nearly as much zinc as the abundant mineral, iron. Our bodies contain 2.5 grams of zinc at any given moment in our lives. The highest concentration reside in areas of muscle and brain tissue, liver, kidneys, pancreas, and adrenal glands, and even the retina of the eye. In men, zinc mineral is found in abundance in the prostate glands as well, and plays a key role in sexual development, functioning, and reproduction.

The mineral zinc is available in a variety of forms for human consumption. The biological forms include:

  • Zinc Acetate
  • Zinc Citrate
  • Zinc Glycerate
  • Zinc Monomethionine
  • Zinc Picolinate
  • Zinc Sulfate

Absorption rates of zinc vary and are dependent on the form ingested. However, medical literature reports a varying absorption rate of 20 - 40%, measured by means of whole food sources consumed in the average American diet. Additional dietary supplementation of zinc will also cause either an increase or decrease in our ability to digest and use various zinc supplements.

Zinc Food Sources

Food Milligrams %DV*
Oysters, battered and fried, 6 medium 16.0 100
Ready-to-Eat (RTE) Breakfast cereal, fortified with 100% of the DV for zinc per serving, 3/4 c serving 15.0 100
Beef shank, lean only, cooked 3 oz 8.9 60
Beef chuck, arm pot roast, lean only, cooked, 3 oz 7.4 50
Beef tenderloin, lean only, cooked, 3 oz 4.8 30
Pork shoulder, arm picnic, lean only, cooked, 3 oz 4.2 30
Beef, eye of round, lean only, cooked, 3 oz 4.0 25
RTE Breakfast cereal, fortified with 25% of the DV for zinc per serving, 3/4 c 3.8 25
RTE Breakfast cereal, complete wheat bran flakes, 3/4 c serving 3.7 25
Chicken leg, meat only, roasted, 1 leg 2.7 20
Pork tenderloin, lean only, cooked, 3 oz 2.5 15
Pork loin, sirloin roast, lean only, cooked, 3 oz 2.2 15
Yogurt, plain, low fat, 1 c 2.2 15
Baked beans, canned, with pork, 1/2 c 1.8 10
Baked beans, canned, plain or vegetarian, 1/2 c 1.7 10
Cashews, dry roasted w/out salt, 1 oz 1.6 10
Yogurt, fruit, low fat, 1 c 1.6 10
Pecans, dry roasted w/out salt, 1 oz 1.4 10
Raisin bran, 3/4 c 1.3 8
Chickpeas, mature seeds, canned, 1/2 c 1.3 8
Mixed nuts, dry roasted w/peanuts, w/out salt, 1 oz 1.1 8
Cheese, Swiss, 1 oz 1.1 8
Almonds, dry roasted, w/out salt, 1 oz 1.0 6
Walnuts, black, dried, 1 o 1.0 6
Milk, fluid, any kind, 1 c .9 6
Chicken breast, meat only, roasted, 1/2 breast with bone and skin removed 0.9 6
Cheese, cheddar, 1 oz 0.9 6
Cheese, mozzarella, part skim, low moisture, 1 oz 0.9 6
Beans, kidney, California red, cooked, 1/2 c 0.8 6
Peas, green, frozen, boiled, 1/2 c 0.8 6
Oatmeal, instant, low sodium, 1 packet 0.8 6
Flounder/sole, cooked, 3 oz 0.5 4

[2]

The amount of zinc found in any one food source is dependant upon a number of factors, including environmental and non-environmental concerns. Chemical fertilizers and certain naturally occurring biological activities in food are influential; for example, the fertilizers and pesticides used to cultivate and protect produce also have been shown to significantly reduce the amount of zinc in soil levels.

Examples of non-environmental factors include the phyates or oxylates found in grains and vegetables, which actually lessen our body’s ability to absorb this critical mineral.

Zinc Uses

The most common and popular usage for zinc supplementation in the general population remains for the benefit of increased immunological functioning. It is suggested that zinc may be directly responsible for the development and activity of certain white blood cells (i.e. T-lymphocytes). The common cold and upper respiratory infections of adults are examples of the afflictions that are aided by proper immune system functioning and white blood cell activity, and have been widely studied in various clinical applications. [3, 4] Zinc lozenges have shown promise in reducing the duration of the common cold and its associated symptoms. [5] This may be due to an oral zinc supplement delivering zinc ions to our oral mucosa/saliva.

An example of the effectiveness of supplemental zinc may be noted when combined with vitamin A in the elderly. A recent study revealed that nearly 80 participants in a two year study were less likely to develop infections than those individuals receiving placebo. [6] Zinc is also important in the elderly for maintaining bone mineral density, thereby aiding in the prevention and treatment of osteoporosis. [7]

Improvements in immune system response has also been researched in patients suffering from illnesses requiring extra nutrients. Burn victims rely on increased caloric and micronutrient intake, such as zinc, to improve their overall health and to speed recovery. [8] Even in the most tragic of circumstances, zinc supplementation may be instrumental in sustaining life. Direct examples are witnessed in the results by HIV, AIDS, and cancer patients. Immune system activity is critical for these individuals. Zinc has been used in conjunction with other specific immune system medications to sustain weight and reduce the possible development of opportunistic infections. [9, 10]

Zinc supplementation may provide greater results in women. Zinc oxide not only boosts the immune system in women, but may be a deterrent in one developing eating and self-image disorders. such as bulimia, anorexia, or body-dysmorphia disorder (BDD). Combined with standard treatment, the supplementation to cure zinc deficiency in these women may assist in weight gain, aid in the regulation of appetite, and improve one’s self-image. [11, 12]

Acne may be another topic of interest concerning zinc supplementation and women. Studies continue, but evidence supports the findings of zinc supplementation to the decrease the inflammation in those persons suffering from chronic acne, and may also be employed in conjunction with standard prescribed acne medications. [13, 14] As well, PMS (premenstrual syndrome) and its connection to zinc are equally important due to zinc serving as the catalyst for the synthesis and proper activity of female hormones. [15]

It is important to note that immune response and other positive physiological effects is not limited to one particular age or sexual demographic. In fact, the benefits of zinc supplementation are still being studied in all age groups and sexes. Current clinical study shows promise in areas other than that of immune system response. Progress is being made on men’s fertility, adult onset diabetes, treatment options for children suffering from attention-deficit hyperactivity disorder (ADHD), and age-related vision impairments, including macular degeneration. [16, 17, 18, 19, 20]

Zinc Dosages

Below is the listed Recommended Daily Allowance (RDA) for the mineral Zinc:

AgeInfants and ChildrenMalesFemalesPregnancyLactation
7 months to 3 years 3 mg
4 to 8 years 5 mg
9 to 13 years 8 mg
14 to 18 years 11 mg 9 mg 13 mg 14 mg
19+ 11 mg 8 mg 11 mg 12 mg

[21]

Therapeutic zinc dosages have been clinically applied in ranges from 30 to 60 mg daily, respectfully, for both men and women. This dosage was used to treat to examine zinc’s affect on specific disease conditions and was marked with varying success.

Zinc Toxicities and Deficiencies

Zinc Toxicities

A tolerable upper level intake of Zinc has been established by National Academy of Sciences and stands at 40 milligrams/per day for adults. Although only a few cases of zinc poisoning have ever been studied, it can occur if excessive amounts of zinc are consumed over a long period of time. Zinc toxicity produces the common side effects of nausea, vomiting, and a metallic taste in the mouth. Other indicators include, and are not limited to; dizziness, increased sweating, headaches, loss of muscular coordination, anemia, and hallucinations.

In extreme cases, mega-doses of zinc may inhibit the absorption of other micronutrients from consumed food sources, primarily copper. Decreased levels of HDL (good) cholesterol and white blood cell count have also been documented.

Zinc Deficiencies

Zinc deficiency remains rare in Western societies. Those at risk for the development of a deficiency state include the elderly, alcoholics/drug addicts, vegetarians, and low income children; this stratum of society is consistently linked with marginal intakes of all nutrients.

Deficiency symptoms include; delayed sexual maturity, anemia, delayed growth (dwarfism), birth defects, sterility, prolonged healing of wounds, white spots on fingernails, fatigue, glucose intolerance, skeletal abnormalities, and the increased susceptibility to infections and disease.

References

1. Hambidge K.M. 1987. Zinc. In: Trace elements in human and animal nutrition. Mertz, W., ed. 5th, Vol. 1., p. 1-137. Orlando, Florida, Academic Press, Inc.

2. U.S. Department of Agriculture, Agricultural Research Service. 2001. USDA Nutrient Database for Standard Reference, Release 14. Nutrient Data Laboratory Home Page, http://www.nal.usda.gov/fnic/foodcomp Search the database online.

3. Hirt M, Nobel Sion, Barron E, Zinc nasal gel for the treatment of common cold symptoms: A double-blind, placebo-controlled trial. ENT J. 2000;79(10):778-780, 82.

4. Belongia EA, Berg R, Liu K. A randomized trial of zinc nasal spray for the treatment of upper respiratory illness in adults. Am J Med. 2001;111(2):103-108.

5. Eby GA. Zinc ion availability-the determinant of efficacy in zinc lozenge treatment of common colds. J Antimicrob Chemother. 1997;40:483-493.

6. Girodon F, Lombard M, Galan P, et al. Effect of micronutrient supplementation on infection in institutionalized elderly subjects: a controlled trial. Ann Nutr Metab. 1997;41(2):98-107.

7. Yamaguchi M. Role of zinc in bone formation and bone resorption. J Trace Elem Exp Med. 1998;11:119-135.

8. De-souza DA, Greene LJ. Pharmalogical nutrition after burn injury. J Nutr. 1998;128:797-803.

9. Patrick L. Nutrients and HIV: part 2-vitamins A and E, zinc, B-vitamins, and magnesium. Alt Med Rev. 2000;5(1):39-51.

10. Kristal AR, Stanford JL, Cohen JH, Wicklund K, Patterson RE. Vitamin and mineral supplement use is associated with reduced risk of prostate cancer. Can Epidemiol. 1999; 8(10):887-892.

11. McClain CJ, Stuart M, Vivian B, et al. Zinc status before and after zinc supplementation of eating disorder patients. J Am Col Nutr. 1992;11:694-700.

12. Humphries L, Vivian B, Stuart M, McClain CJ. Zinc deficiency and eating disorders. J Clin Psychiatry. 1989;50(12):456-459.

13. Dreno B, Amblard P, Agache P, Sirot S, Litoux P. Low doses of zinc gluconate for inflammatory acne. Acta Derm Venereol. 1989;69:541-543.

14. Dreno B, Trossaert M, Boiteau HL, Litoux P. Zinc salts effects on granulocyte zinc concentration and chemotaxis in acne patients. Acta Dermatol Venerol. 1992;72:250-252.

15. Chuong CJ, Dawson EB. Zinc and copper levels in premenstrual syndrorme. Fertil Steril. 1994;62(2):313-320.

16. Anderson RA, Roussel AM, Zourai N, Mahjoub S, Matheau JM, Kerkeni A. Potential antioxidant effects of zinc and chromium supplementation in people with type II diabetes mellitus. J Am Coll Nutr. 2001;20(3):212-218.

17. Baumgaetel A. Alternative and controversial treatments for attention-deficit/hyperactivity disorder. Pediatr Clin of North Am. 1999;46(5):977-992.

18. Toren P, Eldar S, Sela BA, et al. Zinc deficiency in attention- deficit hyperactivity disorder. Biol Psychiatry. 1996;40:1308-1310.

19. Christian P, et al. Zinc supplementation might potentiate the effect of vitamin A in restoring night vision in pregnant Nepalese women. Am J Clin Nutr. Jun2001;73(6):1045-51.

20. Newsome DA, et al. Oral Zinc in Macular Degeneration. Arch Ophthalmol. Feb1988;106(2):192-98.

21. Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. National Academy Press. Washington, DC, 2001.