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Zinc in diet

Definition

Zinc is an important trace mineral that people need to stay healthy. This element is second only to iron in its concentration in the body.

Function

Zinc is found in cells throughout the body. It is needed for the body's defensive (immune) system to properly work. It plays a role in cell division, cell growth, wound healing, and the breakdown of carbohydrates.

Zinc is also needed for the senses of smell and taste. During pregnancy, infancy, and childhood the body needs zinc to grow and develop properly.

Recent information from an expert review on zinc supplements showed that:

• When taken for at least 5 months, zinc may reduce your risk of becoming sick with the common cold.
• Starting to take zinc supplements within 24 hours after cold symptoms begin may reduce how long the symptoms last and make the symptoms less severe.

Food Sources

High-protein foods contain high amounts of zinc. Beef, pork, and lamb contain more zinc than fish. The dark meat of a chicken has more zinc than the light meat.

Other good sources of zinc are nuts, whole grains, legumes, and yeast.

Fruits and vegetables are not good sources, because the zinc in plant proteins is not as available for use by the body as the zinc from animal proteins. Therefore, low-protein diets and vegetarian diets tend to be low in zinc.

Zinc is in most multivitamin and mineral supplements. These supplements may contain zinc gluconate, zinc sulfate, or zinc acetate. It is not clear whether one form is better than the others.

Zinc is also found in some over-the-counter medicines, such as cold lozenges, nasal sprays, and nasal gels.

Side Effects

Symptoms of zinc deficiency include:

• Frequent infections
• Hypogonadism in males
• Loss of hair
• Poor appetite
• Problems with the sense of taste
• Problems with the sense of smell
• Skin sores
• Slow growth
• Trouble seeing in the dark
• Wounds that take a long time to heal

Zinc supplements in large amounts may cause diarrhea, abdominal cramps, and vomiting, usually within 3 - 10 hours of swallowing the supplements. The symptoms go away within a short period of time after the stopping the supplements.

People who use nasal sprays and gels that contain zinc may have side effects such as losing their sense of smell.

Recommendations

The Recommended Dietary Allowance (RDA) for vitamins reflect how much of each vitamin most people should get each day. The RDA for vitamins may be used as goals for each person.

How much of each vitamin you need depends on your age and gender. Other factors, such as pregnancy and illnesses, are also important. Women who are pregnant or breast-feeding need higher amounts. Ask your health care provider which amount is best for you

Dietary Reference Intakes for zinc:

Infants

• 0 - 6 months: 2* milligrams per day (mg/day)
• 7 - 12 months: 3* mg/day

*Adequate Intake (AI)

Children

• 1 - 3 years: 3 mg/day
• 4 - 8 years: 5 mg/day
• 9 - 13 years: 8 mg/day

Adolescents and Adults

• Males age 14 and over: 11 mg/day
• Females age 14 to 18 years: 9 mg/day
• Females age 19 and over: 8 mg/day

The best way to get the daily requirement of essential vitamins and minerals is to eat a balanced diet that contains a variety of foods.

References

Escott-Stump S, ed. Nutrition and Diagnosis-Related Care. 6th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2008.

Sarubin Fragaakis A, Thomson C. The Health Professional's Guide to Popular Dietary Supplements. 3rd ed. Chicago, Il: American Dietetic Association;2007.

Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes: Vitamin C, Vitamin E, Selenium, and Carotenoids. National Academy Press, Washington, DC, 2000.

Singh M, Das RR. Zinc for the common cold. Cochrane Database Syst Rev. 2011 Feb 16;2:CD001364.