by Karen Schroeder Kassel, MS, RD, MEd
Zinc is an essential mineral that is found in almost every cell of the body. It is necessary for proper growth and immune function. Since zinc is not stored in or manufactured by the body, it must be ingested in proper amounts each day.
Oysters are well known for their zinc content. But, other animal foods are also excellent sources of zinc. Although you can get zinc from plant-based foods, it is not as well absorbed.
Zinc's functions include:
The human body is able to adapt to a short-term mild zinc deficiency by absorbing greater amounts from the foods you eat and excreting less. However, sustained inadequate zinc intake will affect bodily functions. While relatively rare in the US among most people, a zinc deficiency can have the following effects:
People who may be at risk for a zinc deficiency include:
Zinc toxicity is rare in the US. However, people who take zinc supplements may reach toxic levels. Oversupplementation with zinc can cause a copper deficiency. Excess zinc may also cause the following:
Major Food Sources
Most of what we eat on a daily basis can give us the amount of zinc we need. Here are some common foods that have zinc:
Remember to read labels. If there is zinc in the food product, it will be listed with the amount.
Sufficient levels of zinc are essential for your immune system to function properly. For example, zinc is required for the development and activity of T-lymphocytes. These are a type of white blood cells that help fight infection.
When people deficient in zinc are given zinc supplements, their immunity improves. These effects are most clearly seen among children in developing countries. For example, when these children are given zinc supplements, they have shorter courses of infectious diarrhea and are at a decreased risk of developing pneumonia.
The Common Cold
Zinc lozenges, nasal sprays, and nasal gels may help to decrease the duration and severity of cold symptoms. They are believed to directly inhibit viruses in the nose and throat. However, this topic is still controversial, since the findings from scientific studies have been mixed. Moreover, nasal gels and sprays may cause permanent loss of smell when used incorrectly.
Some studies of oral zinc have found that the duration of cold symptoms to be shorter when zinc was taken, but each study had different doses, which can affect the outcomes. Age also plays a factor in whether or not zinc relieves cold symptoms. In a review of 17 trials, there was little effect on children and the duration of their cold symptoms.
Zinc has also been studied for its possible preventive effects. A review of zinc studies involving almost 400 children found that daily zinc supplements may reduce the risk of getting a cold.
Some of the more common side effects included bad taste in the mouth, and nausea. If you want to take zinc on a daily basis or at the start of a cold, keep in mind the safe upper intake levels for this mineral:
Absorption of Calcium, Iron, and Copper
Minerals can compete with one another for absorption in the body. This is especially a concern when they are taken at high doses, such as those in supplements.
If you take calcium supplements, but consume little or no zinc, you might need to take a multivitamin/mineral containing zinc. Most multivitamin/mineral pills contain 100% of the Recommended Daily Allowance for zinc.
Large doses of zinc can interfere with the body's absorption of copper and iron, other minerals that are essential. If you are taking a zinc supplement, talk to your doctor about your need for other supplements.
Pregnancy Nutrition Support and Prevention of Preterm Birth
Good nutrition is important during pregnancy for the mother and the baby. This includes eating plenty of fruits, vegetables, and healthy proteins. Your doctor may recommend supplements like a zinc supplement if you are having a hard time with nutrition during pregnancy. Getting correct amounts of zinc may help prevent delivering a baby prematurely.
Academy of Nutrition and Dietetics
National Institutes of Health
Dietitians of Canada
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Last reviewed January 2017 by Michael Woods, MD, FAAP
Last Updated: 1/20/2017