An essential mineral in meat, seafood and supplements. Most studied for colds, diarrhea and growth in children, and macular degeneration.
Ask a doctor or pharmacist first if you:
Zinc is an essential mineral. It is found in some foods, added to others and sold as a supplement.[1] Hundreds of enzymes need it, and it plays a part in immune function, wound healing, growth and taste.[1]
Meat, fish and other seafood are the richest sources, and oysters contain the most.[1] Supplements most often contain zinc sulfate, zinc acetate or zinc gluconate. Zinc is also in some cold lozenges, nasal sprays and denture creams.[1]
The main benefits tested in trials:
A review of 5 trials found that zinc may lower depression symptoms in people who take antidepressants.[9] Some benefits are not supported: zinc with folic acid did not improve sperm quality or live births in a large trial.[10] In pregnancy, zinc made little or no difference to preterm birth or low birthweight.[11]
At or below the upper limit, zinc is unlikely to cause harm. The US sets this limit at 40 mg a day for adults, and the EU at 25 mg.[1][12]
Too much zinc can cause nausea, dizziness, headaches, stomach upset, vomiting and loss of appetite.[1] Doses of 50 mg or more for weeks can lower copper absorption, weaken immune function and lower HDL cholesterol.[1] In a 2012 review of cold trials, zinc taken by mouth caused more bad taste and nausea than placebo.[13]
Zinc can interact with quinolone and tetracycline antibiotics and with penicillamine. Thiazide diuretics raise the loss of zinc in urine.[1] Ask a doctor or pharmacist first if you take one of these medicines or plan to take more than the upper limit.[1]
Zinc is a mineral that hundreds of enzymes need to work.[1] The body holds about 1.5 g of zinc in women and 2.5 g in men.[1]
With each meal, the gut releases zinc into the intestine, and the body must take it back efficiently to keep its zinc balance.[14] The body keeps its zinc steady mainly by changing how much it absorbs and how much it releases into the gut. When intake is very low or low for a long time, losses in urine may also change.[15]
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Trials of zinc gluconate lozenges for colds gave 45 to 276 mg of zinc a day for 4.5 to 21 days.[2] Prevention trials in children most often gave 10 to 15 mg a day.[5] The US recommended intake for adults is 11 mg a day for men and 8 mg for women.[1]
For colds, an earlier review found that lozenges with more than 75 mg of zinc a day shortened colds and lower doses did not.[1] For diarrhea in children, WHO and UNICEF recommend 20 mg a day, or 10 mg for infants under 6 months.[1] The AREDS eye trial gave 80 mg of zinc a day with 2 mg of copper.[16] Trials for period pain gave 7 to 150 mg a day.[8]
The US recommended intake is 2 mg a day up to 6 months, 3 mg at 7 months to 3 years, 5 mg at 4 to 8 years and 8 mg at 9 to 13 years. At 14 to 18 years it is 11 mg for boys and 9 mg for girls. Adults need 11 mg (men) or 8 mg (women), 11 to 12 mg in pregnancy and 12 to 13 mg when breastfeeding.[1] EFSA, the EU food safety authority, sets 7.5 to 12.7 mg for women and 9.4 to 16.3 mg for men. The higher values are for diets with more phytate.[17]
Labels list elemental zinc, the amount of zinc itself, not the weight of the whole compound.[1] Common forms are zinc sulfate, zinc acetate and zinc gluconate.[1] In 15 adults who took 10 mg without food, the body absorbed about 61% from zinc citrate and from zinc gluconate, and 50% from zinc oxide.[18]
In one cold trial, adults started zinc acetate lozenges within 24 hours of the first symptoms and took one every 2 to 3 waking hours.[1] Iron supplements of 25 mg or more taken at the same time can lower zinc absorption.[1] Taking quinolone or tetracycline antibiotics at least 2 hours before or 4 to 6 hours after zinc reduces their interaction.[1]
The US upper limit for adults is 40 mg a day from food and supplements, including in pregnancy. For children it is 4 to 34 mg, by age.[1] The EU upper limit for adults is 25 mg a day.[12] Doses of 50 mg or more for weeks can lower copper absorption.[1] The US limits do not apply to people who take zinc as a treatment, and these people should be under a doctor's care.[1]
Most studies gave 10 to 25 mg a day, for 1 to 3 months.
The counts are study groups. A study group is one set of people in a study who took the same dose. One study can have several groups. These are amounts from studies, not advice for you.
334 of 725 study groups took zinc with something else. This shows what studies gave together, not what works together.
What studies used when they gave zinc for one goal, or to a group of people.
Each protocol describes what studies used, for one goal or for one group of people. It is not advice for you: talk to a doctor before you start a supplement.
11 questions in 4 groups. Open one for the short answer; each has its own page with the full answer and sources.
Oysters contain the most zinc: 3 ounces of farmed raw oysters have 32 mg.[1] Beef, crab, pork, poultry, cheese and fortified breakfast cereals are also good sources.[1]
Zinc per serving in some foods:
Beans, nuts and whole grains contain phytate, which binds zinc in the gut and lowers how much is absorbed. Fruits and vegetables contain very little zinc.[1]
In infants and children, diarrhea is a common sign. Older children may have hair loss, slow growth and frequent infections.[1] Low zinc can also cause loss of appetite and change the senses of taste and smell. In older adults it can slow wound healing.[1]
People with bowel diseases such as Crohn's disease or celiac disease are more likely to run low, and so are people after bariatric surgery.[1] Other groups at risk are vegetarians and vegans, pregnant and breastfeeding women, children with sickle cell disease and people with alcohol use disorder. Infants older than 6 months who get only breast milk are also at risk.[1] Doctors use a blood test of serum zinc, but the result also depends on age, sex, time of day and infections.[1]
They may shorten a cold, but zinc may make little or no difference to the risk of catching one.[2] In a 2024 Cochrane review, colds treated with zinc lasted about 2.4 days less, but the certainty of this result was low.[2] A 2012 review found the effect in adults, not in children.[13]
It may help children older than 6 months who live where zinc deficiency or malnutrition is common.[4] A Cochrane review included 33 trials with 10,841 children. In children older than 6 months, zinc may shorten acute diarrhea by about half a day (low certainty). It probably lowers the number of children still ill on day 7 by 27%.[4] In children with signs of malnutrition, it shortened diarrhea by about a day.[4]
In infants younger than 6 months, zinc had no clear effect, and in both age groups it made vomiting more likely.[4] WHO and UNICEF recommend 20 mg of zinc a day, or 10 mg for infants under 6 months, for 10 to 14 days to treat acute diarrhea in children.[1] In well-nourished children the effect may be small.[1]
In people who already have age-related macular degeneration (AMD), a formula of zinc and antioxidant vitamins probably slows the disease. A 2023 Cochrane review found that people who took it were less likely to progress to late AMD (odds ratio 0.72, moderate certainty).[6] Zinc alone also lowered progression (odds ratio 0.83, moderate certainty).[6]
Zinc lowered blood sugar a little in trials, but a US health body finds the evidence too weak to draw conclusions. A 2019 review of 32 trials with 1,700 people found that fasting glucose fell by about 14 mg/dL and HbA1c by 0.55 percentage points with zinc.[7] The fall in fasting glucose was larger in people with diabetes.[7]
The NIH Office of Dietary Supplements says the evidence is not enough to draw conclusions about zinc for preventing or managing type 2 diabetes. A 2015 Cochrane review on prevention found only 3 small trials.[1] People who take medicines every day should discuss zinc with their doctor or pharmacist.[1]
It may, in period pain that has no other cause (primary dysmenorrhea). A 2024 review of 6 trials with 739 women found less pain with zinc than with placebo.[8] Trials of 8 weeks or more found a larger effect, and doses as low as 7 mg a day helped.[8]
The trials gave 7 to 150 mg of zinc a day, mostly as zinc sulfate. In several trials, women took zinc for 3 to 7 days before or during each period.[8] Side effects did not differ significantly between zinc and placebo.[8]
Not in a large trial. In the US, 2,370 couples planning fertility treatment took part. The men took 5 mg of folic acid and 30 mg of zinc a day, or a placebo, for 6 months.[10] Live births were similar: 34% with the supplement and 35% with placebo.[10]
Most measures of sperm quality did not change. DNA damage in sperm was slightly higher with the supplement (29.7% against 27.2%).[10] Stomach pain, nausea and vomiting were more common with the supplement. The authors concluded that the results do not support folic acid and zinc for male partners in fertility treatment.[10]
Yes. Doses of 50 mg of zinc or more a day, taken for weeks, can lower copper absorption and lead to low copper.[1] In reported cases, too much zinc led to low copper, anemia, low white blood cell counts and sometimes nerve problems.[19]
Zinc can interact with some antibiotics and with penicillamine, and some diuretics lower zinc levels:[1]
Iron supplements of 25 mg or more taken at the same time can lower zinc absorption.[1] People who take a medicine every day should discuss their zinc intake with a doctor or pharmacist.[1]
For absorption, zinc citrate and zinc gluconate did equally well in a small trial, and zinc oxide did worse.[18] For colds, half of the trials in a 2024 Cochrane review used lozenges, most often of zinc gluconate.[2] For any form, the label gives the amount of elemental zinc.[1]
