Zinc tends to fly off the shelves every winter. It shows up in immune blends, cold lozenges, nasal sprays and multivitamins. Your body truly needs zinc, and running low does weaken your immune defenses. But zinc is also a mineral where a little extra goes a long way, and a lot extra can cause problems that sneak up on you.
What zinc does
Zinc is involved in hundreds of processes in the body. It helps your immune cells work properly, helps wounds heal, supports growth in children, and plays a part in taste and smell. Your body does not store much of it, so you need a steady supply from food.
How much you need
The U.S. Office of Dietary Supplements lists these amounts on its zinc fact sheet:
- Men 19 and older: 11 mg a day
- Women 19 and older: 8 mg a day
- During pregnancy: 11 mg a day
- Upper limit for adults: 40 mg a day from all sources
Where to get it
- Oysters are by far the richest source. Just a few contain several days' worth.
- Beef, pork, crab, lobster and poultry
- Beans, chickpeas, lentils
- Pumpkin seeds, cashews, hemp seeds
- Whole grains, dairy and fortified breakfast cereals
Zinc from animal foods is absorbed better than zinc from plants. Plant foods contain phytates, which bind zinc. Soaking, sprouting and fermenting, as in sourdough bread, helps.
Who may run low
- Vegetarians and vegans. They may need up to 50 percent more zinc than the standard amount.
- People with digestive conditions, like Crohn's disease, celiac disease or after weight-loss surgery.
- People who drink heavily. Alcohol reduces zinc absorption and increases loss.
- Older adults who eat less.
- People with sickle cell disease.
Zinc and colds: what the research says
This is where most people's interest lies. Studies of zinc lozenges for colds have produced mixed results, partly because products differ so much in form, dose and how they release zinc. Some reviews found that zinc lozenges, started within 24 hours of the first symptoms, may shorten a cold by a day or so. Other careful reviews found the benefit is uncertain. Zinc does not seem to prevent colds in well-nourished people.
If you want to try zinc lozenges:
- Start within a day of symptoms.
- Use them only for a few days, not for weeks.
- Expect side effects. A bad taste and nausea are common.
See immune support supplements: what the evidence says and cold, flu or COVID: how to tell for the bigger picture.
Do not use zinc nasal sprays
Zinc nasal sprays and swabs have been linked to a long-lasting or permanent loss of smell. The FDA warned consumers about certain zinc nasal products for this reason in 2009. Stick with lozenges or tablets if you use zinc at all.
The hidden risk of too much zinc
Short-term, too much zinc causes nausea, vomiting, stomach cramps and diarrhea. That is unpleasant but obvious.
The bigger concern is quieter. Taking high doses of zinc for weeks or months, often above 40 mg a day, can block your body from absorbing copper. Copper deficiency can cause anemia, low white blood cell counts, and in some cases nerve damage, with numbness and trouble walking. It is easy to slip into this without noticing. Many people stack a multivitamin, an immune blend and lozenges, and some denture creams have contained zinc too.
Add up your zinc from all sources before taking more. Our post on percent daily value on supplement labels shows you how.
Zinc and medicines
Zinc can reduce how well some antibiotics, such as tetracyclines and quinolones, are absorbed. Take them at least two hours apart. Zinc may also interact with penicillamine, used for some rheumatic conditions, and with certain diuretics that increase zinc loss. See supplement and drug interactions and ask your pharmacist.
Choosing a zinc supplement
- Check elemental zinc on the label, not just the compound weight.
- Common forms include zinc gluconate, zinc citrate, zinc picolinate and zinc acetate. For daily use, the form matters less than the dose.
- Keep it modest. For people who need a supplement, 8 to 15 mg is often enough. A basic multivitamin may already cover it. See are multivitamins worth it.
- Choose a tested product. See what third-party tested means.
- Take it with food if it upsets your stomach.
A note on eye health
Zinc is one ingredient in the AREDS2 formula, which the National Eye Institute studied for people with intermediate or advanced age-related macular degeneration. That formula is a specific treatment for a specific condition, recommended by an eye doctor. It is not a general eye health supplement for everyone.
The bottom line
Most people get enough zinc from a varied diet. Vegetarians, older adults and people with digestive conditions may need a bit more. Zinc lozenges may shave a day off a cold if started early, but skip the nasal sprays, and do not take high doses for long periods. For more, see our zinc ingredient page and the minerals category.