Zinc in diet
Zinc is an important trace mineral that people need to stay healthy. Of the trace minerals, this element is second only to iron in its concentration in the body.
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. Zinc also enhances the action of insulin.
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. However, supplementation beyond the RDA is not recommended at this time.
Animal proteins are a good source 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.
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 taken in large amounts may cause diarrhea, abdominal cramps, and vomiting. These symptoms most often appear within 3 to 10 hours of swallowing the supplements. The symptoms go away within a short period of time after stopping the supplements. An excess intake of zinc can lead to copper or iron deficiency.
People who use nasal sprays and gels that contain zinc may have side effects, such as losing their sense of smell.
Dosages for zinc, as well as other nutrients, are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board at the Institute of Medicine. DRI is a term for a set of reference intakes that are used to plan and assess the nutrient intakes of healthy people. These values, which vary by age and gender, include:
- Recommended Dietary Allowance (RDA) -- The average daily level of intake that is enough to meet the nutrient needs of nearly all (97% to 98%) healthy people. An RDA is an intake level based on scientific research evidence.
- Adequate Intake (AI) -- This level is established when there is not enough scientific research evidence to develop an RDA. It is set at a level that is thought to ensure enough nutrition.
Dietary Reference Intakes for zinc:
- 0 to 6 months: 2 mg/day
Children and infants (RDA)
- 7 to 12 months: 3 mg/day
- 1 to 3 years: 3 mg/day
- 4 to 8 years: 5 mg/day
- 9 to 13 years: 8 mg/day
Adolescents and Adults (RDA)
- Males, age 14 and over: 11 mg/day
- Females, age 14 to 18: 9 mg/day
- Females, age 19 and over: 8 mg/day
- Pregnant females, age 19 and over: 11 mg/day (14 to 18 years: 12 mg/day)
- Lactating females, age 19 and over: 12 mg/day (14 to 18 years: 13 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.
Mason JB. Vitamins, trace minerals, and other micronutrients. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 218.
Salwen MJ. Vitamins and trace elements. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. St Louis, MO: Elsevier; 2017:chap 26.
Singh M, Das RR. Zinc for the common cold. Cochrane Database Syst Rev. 2013;(6):CD001364. PMID: 23775705 www.ncbi.nlm.nih.gov/pubmed/23775705.