Zinc: What it does for the body, and the best food sources

The word zinc may conjure images of cold remedies and sunblock. But dietary zinc, found in a variety of foods including seafood, meat, and fortified breakfast cereal, is an important nutrient that plays a vital role in many of the body's functions.

What is zinc?

Zinc is a trace mineral that's essential for the proper functioning of the human body. "Since we cannot produce zinc as an element, we have to eat it," says Teresa Fung, a registered dietitian and adjunct professor of nutrition at the Harvard School of Public Health. Foods including beef, shrimp, and pumpkin seeds contain high levels of the nutrient.

Benefits of zinc: What does zinc do for the body?

Zinc is vital for normal immune system function and wound healing. In addition, the body needs zinc for bone growth, the production of hormones such as insulin and testosterone, sperm production, and fetal development. Your body also needs zinc in order to smell and taste.

How much zinc do you need each day?

The Recommended Dietary Allowance (RDA) for zinc is 11 milligrams (mg) per day for adult men and 8 mg per day for adult women. For pregnant or lactating women, the RDA is 11 mg per day and 12 mg per day, respectively.

What happens if you don't get enough zinc?

Symptoms of zinc deficiency include slow wound healing, poor oral health, loss of taste and smell, skin lesions, hair loss, poor immune response, and diarrhea. Children with zinc deficiency may suffer delayed growth, as well as diarrhea and frequent infections. All of these symptoms, however, could also be the result of other disorders or deficiencies. The only way to confirm deficiency is with a blood test to measure zinc levels in the blood.

The risk of zinc deficiency is higher in older adults, as well as in people who eat a plant-based diet, women who are pregnant or nursing, people with gastrointestinal disorders like Crohn's disease and celiac disease, and those who have had bariatric surgery. Overall, zinc deficiency is rare in the U.S.

Foods high in zinc

Nonvegetarian foods tend to be higher in zinc, with oysters and beef topping the list. Compared to other vegetarian foods, lentils, pumpkin seeds, cheese, and cashews are good sources of zinc. Fortified cereals contain higher levels of zinc as well.

Source: National Institutes of Health Office of Dietary Supplements

Should you take a zinc supplement?

Most people, including vegetarians, can consume enough zinc through a balanced and varied diet. Your doctor may recommend a supplement if a blood test indicates your levels are low. If you are zinc deficient, you may also need further evaluation to identify and then address the underlying cause of your deficiency.

Some people swear by Cold-EEZE, a lozenge containing zinc gluconate, to reduce common cold duration and symptoms. But studies haven't consistently shown it to help that much, or at all. In addition, in one study, the majority of people who used zinc lozenges suffered adverse effects like nausea and bad taste. Zinc nasal sprays may also cause loss of smell. Zinc supplements may interfere with the effectiveness of quinolone and tetracycline antibiotics, so tell your doctor if you are taking a supplement.

Risks of too much zinc

It's hard to consume too much zinc from food. If you are taking a supplement, avoid exceeding the upper safety limit of 40 mg per day. Risks of too much zinc include stomach pain, headaches, cramps, nausea, vomiting, and diarrhea.