How taking zinc may shorten a cold and what you need to know about zinc and your immune system
- Zinc helps your immune system by aiding in the production of immune cells, like T-cells and white blood cells, that help your body fight off diseases.
- Research has shown that taking 75mg of zinc at the onset of a cold can decrease the time you are sick.
- But a regular dose of zinc is 8-11mg, and taking much more than that consistently can actually lead to hindered immune function
- This article was reviewed by Jason R. McKnight, MD, MS, a family medicine physician and clinical assistant professor at Texas A&M College of Medicine.
Zinc is a nutrient that affects many processes throughout your body, including your metabolism and your senses of taste and smell. But zinc is especially important for your immune system, and a zinc deficiency could lead to more illnesses and a longer recovery time.
The recommended daily amount of zinc is 8 milligrams (mg) for adult women and 11 mg for men. Yet, about 12% of Americans do not get enough zinc in their diets, and that percentage rises to 40% for those over 65.
Here's what you need to know about how zinc affects your immune system and whether or not you should take zinc supplements.
What does zinc do for the immune system?
If you have a zinc deficiency, your body will have a hard time creating enough immune cells, like T-cells and white blood cells, that fight off disease. This can lead to getting sick more often and taking longer to heal from illness.
Zinc supports your immune system by helping to fight off certain microbes, including Streptococcus pneumoniae, a type of bacteria that causes the dangerous lung disease pneumonia. Zinc is able to block the pathway these bacteria use to take in nutrients, essentially starving the bacteria and making it easier for your immune cells to kill them. There is no need to load up on zinc, however — just bringing low zinc levels into the normal range can help guard against pneumonia.
In some cases, taking extra zinc above your normal intake may help shorten how long you stay sick, like with the common cold. A review of 5 studies published in 2015 in the Cochrane Database of Systematic Reviews found that people who started taking 75mg zinc lozenges within 24 hours of their first cold symptoms were significantly less likely to still have symptoms a week later, compared with people who didn't take zinc.
This may be because zinc can help block the cold virus from replicating and spreading through your body. However, the review's authors warn that there is no research to support taking zinc when you don't have a cold to prevent yourself from getting sick in the first place. According to their research, it only helps once you've already caught an infection.
How much zinc to take
The amount of zinc you need varies by age. Here's how much you should be taking:
It's important to note that during pregnancy, adult women should be getting about 11mg of zinc and about 12mg if they're breastfeeding.
Should I take a zinc supplement?
Vegetarians may be more likely to need a zinc supplement because meats are the best source of zinc and the extra grains and legumes in a vegetarian diet can decrease your ability to absorb zinc.
"The amount of zinc found in a typical multivitamin designed to take daily is fine to take on a regular basis," says Julie Stefanski, a registered dietitian nutritionist and spokesperson for the Academy of Nutrition & Dietetics.
Standard multivitamins may contain 6mg to 11mg of zinc. If you add extra zinc beyond a multivitamin, you'll only want to do it for a short period of time such as a few weeks, Stefankski says. Because there is such a thing as too much zinc.
Sources of zinc
While you can get zinc through taking supplements, it's best to focus on increasing zinc-rich foods in your diet, Stefanski says. This is because foods containing zinc often have other valuable nutrients like protein, fiber, and other minerals.
Oysters are by far the best source of zinc, providing 3 to 4 times your daily value of zinc in one serving of 6 oysters. Some other good sources of zinc include:
- Beef shoulder steak – 8.7 mg per 3 oz serving
- Ground beef – 5.4 mg per 3 oz serving
- Crab – 4.7 mg per 3 oz serving
- Whole grain oats – 3.8 mg per 1 cup serving
- Turkey (dark meat) – 3 mg per 3 oz serving
Vegetarian-friendly foods also contain zinc, though at lower levels. Some of these foods include soybeans, various nuts, yogurt, and chickpeas.
As with any diet, consistency is key. "Foods rich in zinc need to be included on a daily basis to consume enough," Stefanski says.
Risks of zinc
Though our bodies need zinc, there are risks to taking in too much. "Excessive and prolonged zinc supplementation has been shown to hinder immune function rather than help it," Stefanski says.
The US Food and Nutrition Board advise that you should not take in more than 40mg of zinc per day, between both your diet and supplements. If you're considering a zinc supplement, "the best approach to figure out whether you need to supplement with zinc is to have a registered dietitian evaluate your current diet," Stefanski says.
According to Stefanski, taking too much zinc over a long period "can overwhelm our body's ability to absorb other minerals like copper." A copper deficiency can lead to lower numbers of white blood cells, vital immune cells that help fight off disease.
Taking excess zinc supplements for a long period may also interfere with your ability to absorb iron. If your body becomes too low in iron, your immune cells can be negatively affected and you may have a harder time fighting off illness.
The bottom line
Zinc is an essential nutrient that we need to keep our immune systems running at their optimal level. If you are low in zinc, or you feel a cold coming on, taking in some extra zinc may be a good solution, but it's best to keep this short term. Checking in with your doctor or nutritionist can help you determine how to balance your daily zinc needs and find the best way to support your immune system.