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Zinc Explained: What It Does, How Much You Need, and Safe Limits

Oyster, beans, red meat, and nuts on a light table, all food sources of zinc

Zinc is one of those minerals most people only think about when a cold is coming on and someone suggests zinc lozenges. In reality, your body relies on zinc every day for far more than fighting off colds. It is involved in your immune system, wound healing, growth, and even your sense of taste and smell.

The good news is that most people can get enough zinc from a normal, varied diet. The less obvious news is that zinc supplements are easy to overdo, and too much zinc can cause problems of its own. This guide explains what zinc does, how much you need, the best food sources, who may be at risk of low intake, what the research says about colds, and how to stay within safe limits.

This article is for general educational purposes and is not medical advice. Please see our medical disclaimer.

What Does Zinc Do?

According to the NIH Office of Dietary Supplements (ODS), zinc is found in cells throughout the body. Among its main jobs, zinc:

  • helps your immune system fight off invading bacteria and viruses;
  • is used to make DNA and proteins;
  • is needed for proper growth and development during pregnancy, infancy, childhood, and adolescence;
  • helps wounds heal;
  • is important for a proper sense of taste.

The NHS adds that zinc helps the body make new cells and enzymes and helps process carbohydrate, fat, and protein from food. MedlinePlus notes that, of the trace elements, zinc is second only to iron in its concentration in the body, and that it is also needed for the sense of smell.

How Much Zinc Do You Need?

Recommendations differ slightly between countries, partly because experts use different methods to set them.

In the United States, the NIH ODS lists these daily recommended amounts:

  • Adult men: 11 mg
  • Adult women: 8 mg
  • Pregnant women: 11 mg
  • Breastfeeding women: 12 mg
  • Teens 14 to 18: 11 mg for boys and 9 mg for girls

In the UK, the NHS says men aged 19 to 64 need about 9.5 mg a day and women about 7 mg a day. The NHS also notes that most people can get this amount from their daily diet.

Either way, the amounts are small. Zinc is a trace mineral, so you need only a few milligrams a day, not the larger amounts often found in single-ingredient supplements.

Chart of daily zinc needs: 7 to 9.5 mg in the UK and 8 to 12 mg in the US, with supplement and upper limits

Best Food Sources of Zinc

Many foods contain zinc. The NIH ODS highlights these sources:

  • Oysters, which have very high amounts of zinc;
  • meat, poultry, and fish;
  • seafood such as crab and lobster;
  • fortified breakfast cereals;
  • beans, nuts, and whole grains;
  • eggs and dairy products, which provide some zinc.

The NHS lists meat, shellfish, dairy foods such as cheese, bread, and cereal products such as wheatgerm as good sources. MedlinePlus adds that beef, pork, and lamb contain more zinc than fish, and that the dark meat of chicken has more zinc than the light meat.

Pairing zinc-rich foods with other key nutrients is easy, because many of the same foods also provide protein and iron. Our guides on how much protein you need and iron cover those nutrients in more detail.

Good food sources of zinc, including oysters, red meat, poultry, seafood, fortified cereals, beans, nuts, dairy, and eggs

Why Plant-Based Eaters Should Pay Attention

Zinc from plant foods is harder for the body to use. The NIH ODS explains that beans and grains contain compounds called phytates, which reduce the amount of zinc the body absorbs. MedlinePlus similarly notes that the zinc in plant foods is not as available to the body as the zinc from animal sources, so vegetarian diets tend to be lower in zinc.

This does not mean plant-based diets cannot provide enough zinc. It means it is worth including zinc-containing foods regularly, such as beans, lentils, nuts, seeds, whole grains, and fortified cereals. The NIH ODS notes that vegetarians and vegans might benefit from zinc supplements, so if you eat this way, it can be worth discussing with a doctor or dietitian.

Who May Not Get Enough Zinc?

Most people in the United States get enough zinc from food, according to the NIH ODS. However, some groups may have trouble getting enough:

  • people who have had gastrointestinal surgery, such as weight loss surgery, or who have digestive disorders such as ulcerative colitis or Crohn's disease;
  • people who follow vegetarian or vegan diets;
  • people who are pregnant or breastfeeding;
  • older infants who are breastfed, since breast milk alone does not provide enough zinc after about 6 months;
  • people with alcohol use disorder, because alcohol reduces zinc absorption and increases zinc loss.

Signs of Low Zinc

True zinc deficiency is uncommon in people who eat a varied diet, but it can happen. According to the NIH ODS, zinc deficiency at any age can cause a loss of taste and smell. In children, it can cause slow growth, loss of appetite, and diarrhea. In older children, it can also cause hair loss and frequent infections. In older adults, it can delay wound healing.

Many of these symptoms can have other causes, so they are not a reason to start taking zinc on your own. If you are worried, a health care provider can help work out what is going on.

Does Zinc Help With Colds?

This is the question most people have about zinc. The NIH ODS summarizes the research this way: some studies suggest that zinc lozenges or zinc syrup may speed recovery from the common cold if you start taking them at the start of a cold. However, these products do not seem to affect how severe the symptoms are, and more research is needed to determine the best dose, form, and length of use.

MedlinePlus describes a similar picture, noting that starting zinc within 24 hours of symptoms may shorten a cold, but that taking supplements beyond the recommended dietary amounts is not recommended at this time.

One important caution: MedlinePlus notes that people who use zinc nasal sprays and gels may have side effects such as losing their sense of smell. Lozenges and nasal products are not the same, so read labels carefully.

Zinc is often grouped with vitamin C as a "cold remedy." Our vitamin C guide explains what the research shows for that nutrient too.

Can You Take Too Much Zinc?

Yes. This is the part that is easy to overlook. According to the NIH ODS, signs of too much zinc include nausea, dizziness, headaches, upset stomach, vomiting, and loss of appetite.

Taking too much zinc for a long time can cause more serious problems. The NIH ODS lists lower immunity, low levels of HDL ("good") cholesterol, and low copper levels. The NHS explains that high doses reduce the amount of copper your body can absorb, which can lead to anaemia and weakened bones.

Key limits to know:

  • NHS: do not take more than 25 mg of zinc supplements a day unless advised to by a doctor.
  • NIH ODS: the upper limit for adults is 40 mg a day from all sources combined, including food, drinks, supplements, and medicines.

Remember that zinc can show up in several products at once: multivitamins, cold lozenges, combination mineral supplements, and even some denture adhesive creams. The NIH ODS warns that using large amounts of zinc-containing denture cream, well beyond label directions, could lead to excess zinc and copper deficiency.

Signs of too much zinc: stomach upset, low copper with long-term high doses, and medicine interactions

Zinc and Medicines

Zinc supplements can interact with some medicines. The NIH ODS gives several examples:

  • Some antibiotics: quinolone and tetracycline antibiotics can reduce how much zinc and antibiotic your body absorbs. The NIH ODS suggests taking the antibiotic at least 2 hours before, or 4 to 6 hours after, a zinc supplement.
  • Penicillamine: zinc can reduce how much of this medicine is absorbed, so the two should be taken at least 1 hour apart.
  • Thiazide diuretics: these can increase the amount of zinc lost in urine.

If you take any regular medicines, it is a good idea to tell your doctor or pharmacist about any supplements you use.

My Take

Zinc is a good example of a nutrient where "more" is not better. Because the daily need is only a few milligrams, a single zinc tablet can easily contain several times what you need, and it is surprisingly easy to stack zinc from a multivitamin, a cold lozenge, and a separate supplement without noticing. In my view, the most useful thing most people can do is simply read labels and add up their totals before buying anything new. For most of us, a varied diet with some protein-rich foods and whole grains covers zinc well, and supplements are best saved for situations where a health professional has a specific reason to suggest them.

Frequently Asked Questions

How much zinc do I need per day?

The NIH ODS recommends 11 mg a day for adult men and 8 mg for adult women, with slightly more during pregnancy and breastfeeding. The NHS suggests about 9.5 mg for men and 7 mg for women aged 19 to 64.

What food is highest in zinc?

Oysters contain very high amounts of zinc. Red meat, poultry, seafood such as crab and lobster, and fortified breakfast cereals are also good sources.

Is it safe to take zinc every day?

Taking a modest amount within recommended limits is generally considered safe for most adults. The NHS advises not taking more than 25 mg of zinc supplements a day unless a doctor advises it, and the NIH ODS sets the adult upper limit at 40 mg a day from all sources.

Can zinc lozenges stop a cold?

There is no good evidence that zinc stops a cold. Some studies suggest zinc lozenges or syrup may help you recover a little faster if started at the very beginning of a cold, but they do not seem to make symptoms less severe.

Can too much zinc cause copper deficiency?

Yes. High doses of zinc over time can reduce how much copper your body absorbs. The NHS notes this can lead to anaemia and weakened bones.

The Bottom Line

Zinc is an essential mineral that supports your immune system, wound healing, growth, and your sense of taste and smell. Most people can get enough from a varied diet that includes foods like meat, seafood, dairy, eggs, beans, nuts, and whole grains. People who eat plant-based diets, are pregnant or breastfeeding, or have certain digestive conditions may need to pay closer attention.

If you choose to take zinc supplements, keep the dose modest, count every source, and stay within recommended limits. If you have symptoms that worry you or take regular medicines, talk with a health care provider before starting.

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