Zinc: Roles, Food Sources, Evidence, Excess and Copper
Zinc's roles, food sources, official intake figures by country, what trials found for colds and child diarrhea, side effects, upper limits and how too much zinc can lower copper.
Content last updated . This page has not been medically reviewed.
What is Zinc good for?
What the body uses it for, and how strong the evidence is. A normal job in the body is not proof that extra supplements add benefit; each card says which.
Immune function
Established roleZinc helps the immune system work normally.
Supplements: Supplements correct low zinc; we found no source showing extra benefit when intake is adequate.
Cell growth and division
Established roleThe body needs zinc to make new cells and enzymes.
Supplements: Supplements correct low zinc; we found no source showing extra benefit when intake is adequate.
Wound healing
Established roleZinc helps wounds heal.
Supplements: Supplements help wounds mainly when zinc is low; no source read showing extra benefit otherwise.
Growth in pregnancy, infancy and childhood
Established roleZinc is needed for normal growth and development before birth and in childhood.
Supplements: Supplements correct deficiency; no source read for extra growth in well-nourished children.
Processing carbohydrate, fat and protein
Established roleZinc helps the body break down and use carbohydrate, fat and protein.
Supplements: This is a normal role; we read no evidence that extra zinc raises energy.
Smell and taste
Established roleZinc is needed for normal senses of smell and taste.
Supplements: Supplements correct low zinc; we found no source showing extra benefit when intake is adequate. Zinc nasal sprays and gels may cause loss of smell.
Insulin action
Established roleZinc enhances how insulin works.
Supplements: No evidence read that supplements improve blood sugar.
Reproductive hormone production in males
Deficiency linkLow zinc can lead to hypogonadism in males.
Supplements: Relevant to deficiency only; no evidence read for extra benefit.
Connected topics
Open a group to see how each topic connects and how strong the evidence is.
Health goals (4)
- Immune SupportEstablished role
Zinc is needed for normal immune function. Supplements help if zinc is low; we did not read evidence of extra benefit when intake is adequate.
- Hair SupportDeficiency link
Hair loss is listed as a sign of zinc deficiency. It has many other causes, and extra zinc has not been shown to help hair when zinc is normal.
- Men’s VitalityDeficiency link
Low testosterone production (hypogonadism) in males is listed as a sign of zinc deficiency. This does not show zinc boosts vitality in men with normal zinc.
- Preventive WellnessEstablished role
Getting enough zinc from food is part of basic nutrition. The NHS says most people can get what they need from their diet.
Body systems (8)
- Immune SupportEstablished role
Zinc is needed for normal immune function. Supplements help if zinc is low; we did not read evidence of extra benefit when intake is adequate.
- Immune SystemEstablished role
Zinc is needed for normal immune function. Supplements help if zinc is low; we did not read evidence of extra benefit when intake is adequate.
- Integumentary SystemEstablished role
Zinc helps wounds heal; skin sores and slow-healing wounds are signs of deficiency.
- Metabolism & WeightEstablished role
Zinc helps the body process carbohydrate, fat and protein. This is a normal role, not a weight-loss effect.
- Skin, Hair & BeautyEstablished role
Zinc helps wounds heal; deficiency can cause skin sores and hair loss. Supplements help mainly when zinc is low.
- Digestive SystemDocumented risk
Large zinc supplement amounts may cause diarrhea, cramps and vomiting, usually within 3 to 10 hours.
- Reproductive HealthDeficiency link
Hypogonadism in males is listed as a sign of zinc deficiency.
- Reproductive SystemDeficiency link
Hypogonadism in males is listed as a sign of zinc deficiency.
Body parts (6)
- CellsEstablished role
Zinc is needed for cell growth and division and for making new cells and enzymes.
- Immune SystemEstablished role
Zinc is needed for normal immune function. Supplements help if zinc is low; we did not read evidence of extra benefit when intake is adequate.
- SkinEstablished role
Zinc supports wound healing; skin sores are a sign of deficiency.
- EyesDeficiency link
Trouble seeing in the dark is listed as a sign of zinc deficiency.
- HairDeficiency link
Hair loss is listed as a sign of zinc deficiency, among many other possible causes.
- Reproductive OrgansDeficiency link
Male hypogonadism is listed as a sign of zinc deficiency.
Functional actions (2)
- Cellular RepairEstablished role
Zinc supports cell growth and wound healing, which involve repair of tissue.
- Immune ModulationEstablished role
Zinc supports normal immune function. Evidence of extra effect from supplements in people with adequate zinc was not read.
Root causes (2)
- Nutrient DeficiencyDeficiency link
Not getting enough zinc causes a recognised set of problems such as frequent infections, slow growth and slow wound healing.
- Poor DietDeficiency link
Low-protein and vegetarian diets tend to be low in zinc because zinc in plant foods is less available to the body.
Habits (1)
- Balanced NutritionEstablished role
Zinc comes from foods such as meat, shellfish, dairy, nuts, whole grains and legumes; a varied diet is the usual source.
Biomarkers (3)
- HemoglobinDocumented risk
High zinc doses reduce copper absorption, which can lead to anaemia, shown by low hemoglobin.
- IronDocumented risk
Long-term excess zinc can lead to iron deficiency, so iron status can be affected by too much zinc.
- MagnesiumDocumented risk
Long-term excess zinc can lead to magnesium deficiency.
Conditions & symptoms (9)
- Dietary Zinc DeficiencyDeficiency link
Low zinc from diet, more likely with low-protein or vegetarian diets.
- Zinc DeficiencyDeficiency link
Low zinc causes frequent infections, hair loss, poor appetite, reduced taste or smell, skin sores, slow growth and slow-healing wounds.
- AnemiaDocumented risk
The NHS says high zinc doses reduce copper absorption, which can lead to anaemia.
- Disorder of Copper MetabolismDocumented risk
High or long-term zinc intake reduces copper absorption and can lead to copper deficiency.
- Growth RetardationDeficiency link
Slow growth is a sign of zinc deficiency.
- Taste DisordersDeficiency link
Reduced taste or smell is a sign of zinc deficiency.
- Wound, Non-HealedDeficiency link
Slow-healing wounds are a sign of zinc deficiency; many other causes exist.
- DiarrheaDocumented risk
Large supplement amounts may cause diarrhea, cramps and vomiting.
- HypogonadismDeficiency link
Hypogonadism in males is listed as a sign of zinc deficiency.
Documented risks and interactions (2)
- Risk: too much zinc lowers copper. High or long-term zinc intake can reduce copper absorption, leading to anaemia and weaker bones.
- Risk: stomach upset from large amounts. Large supplement amounts may cause diarrhea, cramps and vomiting.
Overview
Zinc is an essential trace mineral. The NHS (UK) says it helps with making new cells and enzymes, processing carbohydrate, fat and protein, and wound healing. [1] MedlinePlus (US) adds that zinc is needed for the immune system, cell growth, and the senses of smell and taste, and that the body needs it to grow and develop in pregnancy, infancy and childhood. [2] The NHS says you should be able to get all the zinc you need from your daily diet. [1]This page covers zinc as a nutrient. Supplement forms are on Zinc forms compared, colds on Zinc for colds, lozenges and immune claims, nasal products on Zinc nasal sprays and loss of smell.
Evidence labels used below: established nutritional role / deficiency treatment, evidence in at-risk groups, mixed, insufficient evidence and Proper evidence not found (we say where we looked).
Food sources
The NHS lists meat, shellfish, dairy foods such as cheese, and bread and cereal products such as wheatgerm. [1] MedlinePlus says animal proteins are a good source and that beef, pork and lamb contain more zinc than fish. It also lists nuts, whole grains, legumes and yeast, and says zinc in plant foods is not as available to the body, so low-protein and vegetarian diets tend to be low in zinc. [2] We did not read a food-composition table for this page, so it gives no per-serving amounts; see Food vs supplement sources and Pumpkin seeds.Official intake levels
Figures differ by country and are not treatment amounts. All are milligrams (mg) of zinc per day.| Group | Level | Source and year |
|---|---|---|
| Adult men 19 to 64 (UK) | about 9.5 mg a day | NHS, page reviewed 2020 [1] |
| Adult women (UK) | about 7 mg a day | NHS, page reviewed 2020 [1] |
| Males 14 and over (US RDA) | 11 mg | MedlinePlus, reviewed 2025 [2] |
| Females 19 and over (US RDA) | 8 mg (females 14 to 18: 9 mg) | MedlinePlus, reviewed 2025 [2] |
| Pregnancy (US RDA) | 11 mg at 19 and over; 12 mg at 14 to 18 | MedlinePlus, reviewed 2025 [2] |
| Breastfeeding (US RDA) | 12 mg at 19 and over; 13 mg at 14 to 18 | MedlinePlus, reviewed 2025 [2] |
| Children 1 to 3 / 4 to 8 / 9 to 13 (US RDA) | 3 / 5 / 8 mg | MedlinePlus, reviewed 2025 [2] |
| Adults, zinc supplements (UK advice) | do not take more than 25 mg a day unless a doctor advises | NHS, 2020 [1] |
| Adults, all sources (EU tolerable upper level) | 25 mg a day | EFSA overview v11, August 2025 [3] |
The US upper limit could not be verified: the NIH Office of Dietary Supplements page was blocked when we tried to read it, so we do not quote it. EFSA defines the upper level as the maximum chronic daily intake from all sources not expected to pose a risk of adverse effects. [3]
Deficiency
MedlinePlus lists frequent infections, hair loss, poor appetite, problems with taste or smell, skin sores, slow growth and slow-healing wounds among deficiency symptoms. [2] These signs overlap with many other conditions, so symptoms cannot tell you whether zinc is low. Low zinc is a matter for a clinician, who decides on testing and treatment; see Deficiency testing and its limits and Zinc deficiency.Evidence by use
| Use | What the source found | Label |
|---|---|---|
| Preventing colds | Cochrane review (2024): 34 trials, 8,526 people. Zinc may make little or no difference to developing a cold (low certainty). [4] | Mixed |
| Shortening a cold already started | Same review: treatment trials suggest colds may be shorter by about 2.4 days on average, low certainty with big differences between trials. Most trials used lozenges at 45 to 276 mg a day of zinc gluconate, a study amount, not advice. [4] | Mixed, low certainty |
| Diarrhea in young children | Cochrane review (2016): 33 trials, 10,841 children, mostly in regions at high risk of zinc deficiency. In children over 6 months, zinc may shorten diarrhea by about half a day. Evidence does not support use in well-nourished children or those under 6 months. [5] | Evidence in at-risk groups only |
| COVID-19 | A 2023 meta-analysis of four randomized trials found no statistically significant difference in death with zinc, though the trials differed in design. [6] | Insufficient evidence |
| Everyday "immune support" in well-fed adults | Proper evidence not found beyond the cold reviews; searched PubMed and the NCCIH cold digest. | Marketing claim |
Labels and quality
Multivitamins, lozenges and immune blends can each contain zinc, so totals add up; see Amounts and duplicate ingredients and Quality testing and certifications. MedlinePlus says it is not known whether one zinc form (gluconate, sulfate, acetate) is better than another. [2]Frequently asked questions
Is it safe to take zinc every day?
The NHS advises against more than 25 mg a day of zinc supplements unless a doctor advises it, and EFSA gives 25 mg a day from all sources as the adult upper level. Ask a pharmacist or clinician about your own situation. [1][3]
Does zinc prevent colds?
The 2024 Cochrane review found zinc may make little or no difference to getting a cold, with low-certainty evidence that it might shorten a cold already under way. [4]
Can too much zinc cause copper deficiency?
Yes. The NHS and MedlinePlus both say high or long-term zinc intake can lower copper. Case reports describe anemia that improved after zinc was stopped. [1][2][7]
Do vegetarians need extra zinc?
MedlinePlus says vegetarian diets tend to be low in zinc because plant zinc is less available. Whether to supplement is a question for a clinician or dietitian. [2]
Do zinc nasal sprays work?
They are not recommended: MedlinePlus lists loss of smell as a side effect, and NCCIH says intranasal zinc should not be used. [2][9]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Side effects and too much zinc
The NHS says high doses of zinc reduce the amount of copper the body can absorb, which can lead to anemia and weaker bones. [1] MedlinePlus says long-term excess can lead to copper, iron or magnesium deficiency. [2] A 2026 systematic review of 37 case reports found that zinc-related anemia, often with low white cells, came mostly from oral supplements, denture adhesive creams and swallowed coins, with all patients having low copper. Most recovered after zinc was stopped and copper given under medical care. [7] These are case reports, so they cannot say how common the problem is. See Zinc toxicity and copper deficiency and Copper.
Medicines and safety groups
- Medicines: the NHS lists medicines or supplements containing iron or zinc among things that may not mix well with doxycycline. [8] NCCIH notes zinc may interact with antibiotics and penicillamine. [9] Ask a pharmacist about timing; see Spacing supplements and medicines and Medication interactions.
- Nasal products: MedlinePlus says zinc nasal sprays and gels may cause loss of smell. [2]
- Pregnancy, breastfeeding and children: needs are higher in pregnancy (table above). Supplements for children, and for pregnancy, should be chosen with a clinician; see Pregnancy and breastfeeding and Children and teens.
- Kidney, liver, surgery: we did not find a source in our reading giving zinc-specific rules for these, so ask a clinician; see Liver safety and Supplements before surgery.
- Swallowed in excess: for a suspected overdose in the US call Poison Help 1-800-222-1222, or 911 if the person is very unwell; other countries are on Poison help by country.
References
- NHS, Vitamins and minerals: Others (chromium, copper, manganese, molybdenum, selenium, salt, zinc; page last reviewed 3 August 2020). Read 2026-10-22.
- MedlinePlus Medical Encyclopedia, Zinc in diet (review date 1/21/2025). Read 2026-10-22.
- EFSA, Overview on Tolerable Upper Intake Levels as derived by the SCF and the EFSA NDA Panel, version 11 (August 2025). Read 2026-10-22.
- Nault D et al. Zinc for prevention and treatment of the common cold. Cochrane Database Syst Rev. 2024. PubMed 38719213. Read 2026-10-22.
- Lazzerini M, Wanzira H. Oral zinc for treating diarrhoea in children. Cochrane Database Syst Rev. 2016. PubMed 27996088. Read 2026-10-22.
- Wu JY et al. The effect of zinc on the outcome of patients with COVID-19: a systematic review and meta-analysis of randomized controlled trials. J Infect. 2023. PubMed 36693569. Read 2026-10-22.
- Zinc-induced hematologic toxicities: a systematic review of descriptive studies. Biol Trace Elem Res. 2026. PubMed 42087025. Read 2026-10-22.
- NHS, Doxycycline (medicine page). Read 2026-10-22.
- NCCIH, The Common Cold and Complementary Health Approaches: What the Science Says (December 2020). Read 2026-10-22.