Zinc, present in every cell in your body, is an essential mineral. “Essential” refers to any nutrient you must get from diet or supplements, because your body cannot make it. Without enough zinc, you are at increased risk of infection. An important part of cellular metabolism, zinc’s functions are categorized as catalytic, structural and regulatory.
Zinc and Health
Zinc’s catalytic function assists in the chemical reactions of almost 100 enzymes, its structural function is important for cell membranes and protein structure, and its regulatory function impacts hormone release, nerve impulse transmission and gene expression. Zinc is necessary for reproduction, growth, insulin and thyroid function, taste, vision, smell and blood clotting. It is also necessary for a healthy immune system. For example, enzymes in skin, tears and oils help prevent organisms from entering wounds, white blood cells destroy invaders and blood proteins called antibodies help you develop resistance to harmful organisms. Zinc’s roles in enzymatic reactions, gene expression and cell and protein formation directly impact these immune responses.
Zinc and Infection
Zinc lozenges or syrup can reduce the duration and severity of cold symptoms, and zinc ointments can relieve herpes simplex symptoms. In malnourished children, zinc supplements reduce the severity and duration of infectious diarrhea. Because even mild to moderate deficiency adversely affects white blood cells, zinc deficiency increases the risk of pneumonia and other infections, especially in children and the elderly, and low zinc levels contribute to reduced skin integrity, leading to chronic leg ulcers. It is not clear, however, whether zinc supplements prevent infections or hasten healing in people who are not deficient.
Recommended Intake
An adequate intake of zinc for infants until 6 months of age is 2 mg; from 7 months to 3 years, the dietary reference intake, or DRI, is 3 mg. The DRI for children 4 to 8 is 5 mg; from 9 to 13, it increases to 8 mg. The DRI for zinc for men and boys over age 14 is 11 mg. Girls ages 14 to 18 need 9 mg. Pregnant teens need 11 mg, and breastfeeding teens need 12. The DRI for women over 18 is 8 mg. That increases to 11 mg for pregnant women and 12 mg for nursing mothers.
Dietary Sources
You absorb only 20 to 40 percent of zinc in food. Zinc in food from animal sources is more easily absorbed than zinc from plant sources. Oysters are the richest dietary source of zinc, followed by other shellfish, poultry, red meat and cheese. Plant sources include legumes, whole grains, brewer’s yeast, tofu, miso, tahini, green beans, cooked greens, mushrooms, pumpkin and sunflower seeds.
Supplements and Precautions
Different forms of supplements exist. Zinc sulfate, which may cause stomach upset, is not as easily absorbed as zinc picolinate, zinc citrate, zinc acetate, zinc glycerate and zinc monomethionine. Most drugstores sell zinc lozenges for colds and nasal sprays and gels for nasal and sinus congestion. Because high doses can damage your immune function, lower good cholesterol, raise bad cholesterol and interact with some medications, you should use supplements only on the advice of your doctor.
References
- University of Maryland Medical Center; Zinc; S. Ehrlich; June 2009
- Linus Pauling Institute Micronutrient Information Center; Zinc; J. Higdon et al.; March 2011
- National Institutes of Heath Office of Dietary Supplements: Zinc
- University of Maryland Medical Center; Immune Response -- Overview; D. Dugdale et al.; May 2008
- Institute of Medicine Food and Nutrition Board: Dietary Reference Intakes (DRIs)
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