When it comes to essential minerals, zinc may not be on your radar. However, zinc plays a huge role in health — especially when it comes to keeping your immune system healthy.
"Anyone at risk for a zinc deficiency runs the risk of getting sick more often and having a poor immune function," says Jeanette Kimszal, RDN of Root Nutrition Education & Counseling.
"This can result in a greater chance of not being able to properly fight off bacteria and viruses."
Zinc and Your Immune System
Zinc plays a role in the growth and functioning of immune cells, according to the Harvard T.H. Chan School of Public Health.
If you don't get enough of this mineral, the cells that protect your body from viruses and bacteria — lymphocytes, neutrophils and macrophages — can't do their job as well.
In fact, short-term zinc deficiency caused a decrease in immunity while chronic deficiency also increased inflammation, April 2015 research in Autoimmunity Reviews shows.
"Zinc is not a routine lab that is tested and many people could be at risk without knowing it. Even a slight deficiency can affect the immune system function."
Getting enough zinc was found to increase immune reactivity while not getting enough is linked to getting more infectious diseases of upper and lower respiratory tract, per an April 2020 review in the International Journal of Molecular Medicine.
Researchers state that getting enough zinc may possess a protective effect on COVID-19 through reducing lung inflammation and helping to clear out the lungs, preventing ventilator-induced lung injury as well as modulating antibacterial and antiviral immunity — especially in older adults. They chalk these potential benefits to zinc's anti-inflammatory effects, pinpointing zinc supplementation as a potential way to prevent pneumonia and its complications.
Even children's immune systems can take a blow if they don't get enough zinc.
Research published in the 2016 issue of Allergologia et Immunopathologia shows that 5 daily milligrams of zinc decreased the incidence of upper respiratory tract infections in infants, while a small May 2019 study in Pediatric Reports concluded that 30 milligrams of zinc per day decreased the length of an acute lower respiratory infection in children.
In fact, supplementing with zinc when you're sick has been shown to help with symptoms. Zinc lozenges have an effect on the duration of the common cold, a May 2017 study in JRSM Open determined.
People who took zinc lozenges with dosages between 80 and 207 milligrams per day reduced the duration of their colds between 28 and 40 percent.
If you find yourself getting sick often, talk to your doctor about getting tested for a zinc deficiency.
"Zinc is not a routine lab that is tested and many people could be at risk without knowing it," Kimszal says. "Even a slight deficiency can affect the immune system function."
How Much Zinc Do You Need?
Your body doesn't need a lot of zinc, but getting enough is very important.
"Zinc is a 'trace mineral,' meaning we only need very small amounts of it," says Julie Cunningham, MPH, RD.
Zinc Recommended Dietary Allowances (RDAs)
0 to 6 months
7 months to 3 years
4 to 8 years
9 to 13 years
14 to 18 years
19 years and up
A zinc deficiency — which affects about 2 billion people worldwide including 30 percent of the elderly population, according to a December 2017 report in Nutrients — is typically seen in people who have digestive disorders or chronic liver or kidney disease, according to the Harvard T.H. Chan School of Public Health.
Vegetarians and vegans are also at a slightly higher risk of a zinc deficiency because plant-based sources of the mineral have a lower bioavailability than animal-based foods.
"Zinc deficiency may show up as a loss of appetite, loss of sense of taste or smell, diarrhea, decreased immunity or poor wound healing and low or depressed mood," Cunningham says.
Be careful, though, because you can get too much zinc — the tolerable upper intake level is 40 milligrams for both adult men and women, according to the National Institutes of Health (NIH).
However, it takes longterm consumption of too much zinc to cause toxicity, and it's usually due to taking too many zinc supplements, the Harvard T.H. Chan School of Public Health notes.
"Too much zinc supplementation can cause nausea and vomiting," Cunningham says. Additionally, "Taking too much zinc in pill form can limit iron absorption, causing iron-deficiency anemia."
Foods High in Zinc
Thankfully, it's not too difficult to get enough zinc in your daily meal plan.
In the U.S., red meat and poultry typically provide the most zinc, according to the NIH. If you're looking for zinc on a nutrition label, though, keep in mind that the FDA does not require food labels to list it unless zinc has been added to the food.
If you need more zinc in your diet, aim to include some of these zinc-rich foods:
- Oysters: Six Eastern oysters provide you with 52 milligrams of zinc, a whopping 472 percent of the DV.
- Beef (chuck steak): A 5-ounce chuck steak has 15 milligrams of zinc, 140 percent of the DV.
- Chicken leg: Each roasted chicken leg contains 5 milligrams of zinc, 49 percent of the DV. And 3 ounces of roasted turkey has 27 percent of the DV.
- Firm tofu: A cup of firm tofu contains 4 milligrams of zinc, which equals 36 percent of the DV.
- Lean pork chops: A 6-ounce pork chop contains 4 milligrams of zinc, for 32 percent of the DV.
- Hemp seeds: Each ounce of hemp seeds has 3 milligrams of zinc, which is 26 percent of the DV.
- Lentils: A cup of cooked lentils contains 3 milligrams of zinc, or 23 percent of the DV.
- Non-fat yogurt: Each cup of low-fat yogurt has 2 milligrams of zinc, or 22 percent of the DV.
- Oatmeal: A cup of cooked oatmeal contains 2 milligrams of zinc, 21 percent of the DV.
- Shiitake mushrooms: A cup of cooked shiitake mushroom has 2 milligrams of zinc, or 18 percent of the DV.
- National Institutes of Health Office of Dietary Supplements: "Zinc"
- Harvard T.H. Chan School of Public Health: "Zinc"
- Pediatric Reports: "A Randomized Controlled Trial of Zinc Supplementation in the Treatment of Acute Respiratory Tract Infection in Thai Children"
- Nutrients: "Zinc as a Gatekeeper of Immune Function"
- Allergologia et Immunopathologia: "Effects of Zinc Supplementation in the Prevention of Respiratory Tract Infections and Diarrheal Disease in Colombian Children: A 12-month Randomised Controlled Trial"
- Autoimmunity Reviews: "Zinc and Its Role in Immunity and Inflammation"
- JRSM Open: "Zinc Lozenges and the Common Cold: A Meta-Analysis Comparing Zinc Acetate and Zinc Gluconate, and the Role of Zinc Dosage"
- MyFoodData: Top 10 Foods Highest in Zinc
- International Journal of Molecular Medicine: "Zinc and respiratory tract infections: Perspectives for COVID‑19 (Review)"