Zinc in Ireland: Benefits, Deficiency, How Much to Take and Which Form

Zinc is in every chemist and supermarket in Ireland, usually next to the vitamin C in winter. Unlike most of the ingredients in our evidence guides, it carries authorised EU health claims. This guide explains, in plain language, what zinc does, who in Ireland is likely to be short of it, what the cold and immune trials found, how much is enough and how much is too much, which form to buy, and how to take it without upsetting your copper.

Zinc (Zn) definition: Zinc is an essential trace mineral required as a structural and catalytic component of several hundred enzymes and proteins, including those involved in immune cell function, DNA and protein synthesis, wound healing and taste. The body has no dedicated, readily mobilisable zinc store, so a regular dietary supply is needed; it is supplied in supplements as zinc salts or chelates such as zinc picolinate, gluconate, citrate, bisglycinate, methionine and oxide, each providing a stated amount of elemental zinc.

What is zinc and what does it do in the body?

Zinc is a trace mineral. "Trace" means you need small amounts, around 10 mg a day, but it is involved in a very large number of jobs. Several hundred enzymes and proteins need a zinc atom to hold their shape or do their work. That is why the authorised claims cover such a spread: immune cells, skin, hair, nails, bones, eyes, DNA, hormones and the senses of taste and smell all depend on zinc-containing proteins.^[13]

The body holds roughly 1.5 to 2.5 g of zinc, mostly in muscle and bone, but that is not a reserve it can readily draw on in the way it draws on vitamin D in fat or iron in ferritin. So a regular dietary supply matters. How quickly a low intake shows depends on starting status, absorption and losses; immune cells, which divide quickly, are among the tissues most sensitive to it.^[13]

Zinc benefits: colds, immunity, skin, hair, acne and men's health

"Zinc benefits" pages list everything from colds to libido. The honest way to read the evidence is in two layers. Layer one is the authorised claims: zinc contributes to the normal working of the immune system, skin, hair, nails and so on. These are robust because they describe what zinc does when you have enough of it. Layer two is the trial question: does taking extra zinc change anything? That depends almost entirely on whether you were short to begin with.

The studies, one by one

Zinc deficiency: symptoms and who is at risk in Ireland

Severe zinc deficiency is rare in Ireland. Low intake is more common. The National Adult Nutrition Survey II, run by the Irish Universities Nutrition Alliance in 2020 to 2021 with 1,000 adults, estimated that usual zinc intake, from food and supplements together, was below the EFSA average requirement in 28% of adults aged 19 to 64 and 35% of adults aged 65 and over, after excluding people who under-reported what they ate. These are modelled estimates from two dietary recalls per person, published as a conference abstract; they indicate a risk of inadequate intake and do not show that those proportions have clinically confirmed deficiency. Zinc was the fifth most common nutrient shortfall in working-age adults, after vitamin D, vitamin C, folate and calcium, and the fourth most common in over-65s. Only 1 to 2% exceeded the upper limit.^[6]

Symptoms of zinc deficiency

The classic signs, from the clinical literature summarised by the NIH Office of Dietary Supplements, are more frequent infections, slow wound healing, loss of appetite, a dulled sense of taste or smell, hair thinning, skin problems such as dermatitis around the mouth and eyes, and, in children, slowed growth.^[20] None of these is specific to zinc. Hair thinning in particular has a long list of causes, which is why "zinc for hair" as a search term so often leads to disappointment: if your zinc is normal, zinc tablets are not the answer, and a GP visit is a better first step than a bottle.

Zinc-rich foods: what to eat

Food comes first, and for zinc the ranking is unusual: one food is in a league of its own. The figures below are from the NIH Office of Dietary Supplements, which uses standard portion weights; a "3 oz" portion is about 85 g, roughly a deck of cards.^[20]

How much zinc per day, and is 50 mg too much?

There are four numbers worth knowing, and they are easily confused, which is how people end up taking five times what they need.

1. The NRV, 10 mg. This is the EU labelling reference value, the number "% NRV" on a label is measured against. It is a rounded figure for labelling, not a personal target.^[21]

2. The PRI, 7.5 to 16.3 mg. EFSA's 2014 opinion sets population reference intakes that rise with the amount of phytate in the diet: for women 7.5, 9.3, 11.0 and 12.7 mg a day at phytate intakes of 300, 600, 900 and 1,200 mg; for men 9.4, 11.7, 14.0 and 16.3 mg. A typical Irish mixed diet sits in the lower-middle of that range; a wholefood vegan diet sits at the top. Pregnancy adds 1.6 mg and breastfeeding 2.9 mg.^[2] The HSE uses simpler figures: about 9.5 mg a day for men and 7 mg for women.^[5]

3. The UL, 25 mg. The tolerable upper intake level for adults, from all sources combined, is 25 mg a day. It was set by the EU Scientific Committee on Food in 2003, is carried in EFSA's current overview of upper levels (2025) with no revision underway, and was adopted by the FSAI for the Irish market in its 2018 and 2020 reports.^[3][4] The HSE's wording is plain: "Do not take more than 25 mg of zinc supplements a day unless advised to by your GP."^[5] The basis is copper: at sustained intakes above this level, zinc measurably reduces copper absorption. The US limit is 40 mg, which is why American labels look more relaxed.

4. The 50 mg products. "Is 50 mg of zinc too much?" is one of the most-searched zinc questions in Ireland, and the answer is: for daily, open-ended use, yes. Fifty milligrams is twice the EU upper limit before any zinc from food is counted. The NOW Foods labels for both 50 mg products say so in their own way: "This product is not intended for long term use; use only as directed" and "Do not use if pregnant or nursing." Higher doses are used for specific clinical purposes under professional advice, such as correcting a confirmed deficiency. A swallowed 50 mg tablet is not equivalent to the zinc lozenges studied in cold trials, and a "not for long-term use" label does not define a suitable self-directed course. If you are reaching for a 50 mg tablet to take every day, speak to a GP or pharmacist first, or look at a lower-dose product.

With food or without? Morning or night?

Zinc on an empty stomach commonly causes nausea, so every product here says to take it with a meal. Absorption from a meal is slightly lower than from water alone, but the difference is small compared with the difference between taking it and skipping it because it made you feel sick. Time of day does not matter in any trial we are aware of; "can you take zinc at night" is answered by whichever meal you will remember it with. Keep it 2 hours away from iron supplements at 25 mg or more, which reduce zinc absorption, and away from the antibiotics listed in the safety section.^[20]

Zinc picolinate vs gluconate vs citrate vs bisglycinate vs oxide

"Which zinc supplement is best" usually means "which form". Every form delivers elemental zinc; the salt it is bound to affects how much is absorbed, how it tastes and how it sits in the stomach. Here is what has actually been measured.

Zinc with copper, magnesium, vitamin C, vitamin D and iron

Zinc and copper. This is the pairing that matters. Zinc and copper compete for absorption, and high zinc induces a gut protein that traps copper. Duncan and colleagues at Glasgow Royal Infirmary (Journal of Clinical Pathology, 2015) reviewed 70 patients prescribed zinc: 62% were on doses high enough to cause copper deficiency, plasma copper had been measured in only two of them, 9% developed unexplained anaemia and 7% developed neurological symptoms typical of copper deficiency.^[16] The HSE notes that high zinc doses reduce copper absorption and can lead to anaemia and weakened bones.^[5] That audit concerned prescribed, mostly high-dose zinc; it does not show that everyone taking a modest dose needs added copper. If you take zinc daily for months, it is reasonable to check that your diet supplies copper (adults need about 1.2 mg a day) or to ask a pharmacist. Some products, such as Jarrow Zinc Balance, include 1 mg. Added copper does not make a high zinc intake appropriate.

Zinc and magnesium. No absorption conflict at normal doses; they are commonly combined ("ZMA" products). Taking them together is fine. For which magnesium to pair it with, see our which magnesium is best guide.

Zinc and vitamin C. The winter pairing in every Irish chemist. They do not interfere with each other, but the cold evidence for each is separate and, for vitamin C, also modest. Combining them is harmless; it is not a "flu bomb".

Zinc and vitamin D. No interaction; both are commonly low in Irish adults in winter (vitamin D was the most prevalent shortfall in NANS II, at 61% of working-age adults). Taking them together is fine; see our vitamin D3 Ireland guide.

Zinc and iron. Supplemental iron at 25 mg or more reduces zinc absorption when taken at the same time; iron in food or fortified cereal does not.^[20] If you take an iron supplement, separate it from zinc by a couple of hours.

Side effects, medicines and when to see a GP

At label doses with food, zinc is well tolerated. The common complaints are nausea (especially on an empty stomach), a metallic taste, and, with lozenges, a bad taste in up to 80% of users in the Mossad trial.^[11] The Cochrane review found non-serious side effects 34% more common with zinc than placebo and no serious adverse events in the treatment trials.^[7] The NIH lists nausea, vomiting, loss of appetite, stomach cramps, diarrhoea and headaches with excess intake, and notes that 50 mg or more a day for weeks can impair copper absorption, reduce immune function and lower HDL cholesterol.^[20]

When to see a GP instead

Recurrent infections, hair loss, persistent skin problems, a lost sense of taste or smell, or fatigue each have many causes, and zinc is rarely the first one a GP will look at. If you suspect deficiency, a blood test can measure serum zinc, with the caveat that it drops during any illness or inflammation and can read low in someone whose zinc is fine.^[16] Anyone taking more than 25 mg a day for more than a few months should ask for copper to be checked too.

Zinc in Ireland: FSAI status, HSE advice, VAT

Zinc supplements are sold in Ireland by pharmacies, supermarkets, health stores and online retailers as food supplements. Unlike most of the ingredients in our evidence guides, zinc comes with authorised health claims, so a retailer may say that zinc contributes to the normal function of the immune system or the maintenance of normal skin, hair and nails, provided the product supplies at least 1.5 mg per daily portion. What a retailer may not say is that zinc "boosts" immunity, "fights" infection, treats acne or raises testosterone; those are not authorised claims and some are medicinal claims.^[1]

How to choose a zinc supplement

Four questions settle it. This comparison covers the four products sold by Probiotic.ie; details were checked against the manufacturers' published labels and our live listings on 11 November 2026.

1. How many milligrams, counted with your food? The 25 mg limit is for total intake. A 15 mg supplement leaves more room for dietary zinc; 22 mg is close to the limit before food is counted; 50 mg exceeds it on its own. No dose here suits everyone indefinitely; if you plan to take zinc daily for months, check the dose with a pharmacist or GP.

2. Does it include copper? Zinc competes with copper for absorption. Jarrow Zinc Balance is the only product here that includes copper (1 mg). That does not make any zinc dose risk-free, and not everyone taking zinc needs added copper.

3. Which form? Citrate and gluconate have good direct absorption data; evidence that picolinate is superior is weak; oxide was less well absorbed in comparative research. Evidence does not identify one best form.

4. Capsule or tablet, vegan or not? Jarrow (hypromellose capsule) and NOW Zinc Picolinate (hypromellose) are vegan. NOW Zinc 50 mg is a vegetarian tablet. The Swanson 22 mg capsule is listed as vegan by the manufacturer; our listing has shown a gelatin version, so check the label on the bottle you receive.

Frequently asked questions

What is zinc good for?

Zinc is an essential mineral that the body needs every day for hundreds of enzymes to work. Under Commission Regulation (EU) 432/2012 there are 18 authorised health claims for zinc: it contributes to the normal function of the immune system, the maintenance of normal skin, hair, nails, bones and vision, the maintenance of normal testosterone levels in the blood, normal fertility and reproduction, normal cognitive function, the protection of cells from oxidative stress, normal DNA and protein synthesis, normal acid-base, carbohydrate, macronutrient and fatty acid metabolism, normal metabolism of vitamin A, and it has a role in cell division. Every claim is phrased as contributing to normal function; none says zinc improves these things in people who already have enough. In Ireland, zinc supplements are food supplements regulated by the FSAI, not medicines.

How much zinc should I take a day?

The requirement is for total intake, and the HSE says you should be able to get all the zinc you need from your daily diet; a supplement is a top-up where diet falls short, not a requirement for most adults. The EU nutrient reference value is 10 mg; EFSA's population reference intakes (EFSA Journal 2014;12(10):3844) are 7.5 to 12.7 mg a day for women and 9.4 to 16.3 mg for men, higher for diets rich in wholegrains and pulses; the HSE quotes about 9.5 mg for men and 7 mg for women. The tolerable upper intake level for adults is 25 mg a day from food and supplements combined, set by the EU Scientific Committee on Food and adopted by EFSA and the FSAI, and the HSE advises not to take more than 25 mg of zinc supplements a day unless your GP advises it. Pregnancy adds about 1.6 mg and breastfeeding 2.9 mg to the requirement, within the same 25 mg limit. Because the limit counts food and supplements together, a 15 mg or 22 mg supplement can bring total intake to or above 25 mg depending on diet. Follow the label of the product you have.

Is 50 mg of zinc too much?

For daily, long-term use, yes. Fifty milligrams is twice the EU tolerable upper intake level of 25 mg a day for adults, a limit that covers food and supplements combined and which EFSA, the FSAI and the HSE all use, and NOW Foods labels its own 50 mg zinc products as not intended for long-term use and not for use in pregnancy or breastfeeding. The reason is copper: sustained zinc intakes above the limit reduce copper absorption, and copper deficiency can cause anaemia and nerve damage. In an audit of 70 patients prescribed zinc (Duncan et al., Journal of Clinical Pathology, 2015), 9 percent developed unexplained anaemia and 7 percent neurological symptoms typical of copper deficiency. Higher doses have been used in trials, for example 45 mg a day for a year in a monitored study of older adults and lozenges at 80 to 92 mg a day for a few days during a cold; a swallowed 50 mg tablet is not equivalent to those lozenges. Higher doses may be used for specific clinical purposes under professional advice, and a not-for-long-term-use label does not define a suitable self-directed course.

Does zinc help with colds and the immune system?

Zinc contributes to the normal function of the immune system, which is an authorised EU health claim, and people who are short of zinc have weaker immune responses. Whether extra zinc helps a cold is less clear. The 2024 Cochrane review (Nault et al., 34 randomised trials, 8,526 people) found zinc made little or no difference to the chance of catching a cold (risk ratio 0.93, 95 percent confidence interval 0.85 to 1.01) and may shorten a cold by about 2.4 days, but rated that evidence low certainty because trials disagreed. Hemilä's 2017 meta-analysis of seven zinc lozenge trials found colds 33 percent shorter at 80 to 92 mg a day, while his own 2020 randomised trial of zinc acetate lozenges (253 people randomised, 87 who caught a cold analysed) found no benefit. Most of the treatment evidence concerns lozenges started within a day of symptoms, and it should not be assumed to apply to swallowed capsules or tablets. Zinc is not a cold cure and is sold in Ireland as a food supplement, not a medicine.

What are the symptoms of zinc deficiency?

Common signs, as summarised by the NIH Office of Dietary Supplements, include more frequent infections, slow wound healing, loss of appetite, a dulled sense of taste or smell, hair thinning, skin problems such as dermatitis around the mouth and eyes, and, in children, slowed growth. None of these is specific to zinc, and hair thinning in particular has many other causes. In Ireland, a National Adult Nutrition Survey II analysis (Kehoe et al., 2024) estimated that usual zinc intake, including supplements, was below the EFSA average requirement in 28 percent of adults aged 19 to 64 and 35 percent of those aged 65 and over; that indicates a risk of inadequate intake, not clinically confirmed deficiency. Groups at higher risk include older adults, vegetarians and vegans, people with coeliac disease or inflammatory bowel disease, heavy drinkers and people who have had weight-loss surgery. A GP can check serum zinc, bearing in mind that it falls during any illness or inflammation and can read low in someone whose zinc is fine.

What foods are high in zinc?

Oysters are far ahead of everything else, at roughly 28 to 32 mg per 85 g portion, about three days' worth. After that, per standard portion (NIH Office of Dietary Supplements, 2026): roast beef 3.8 mg per 85 g, crab 3.2 mg, cooked porridge oats 2.3 mg per cup, pumpkin seeds 2.2 mg per 28 g, pork chop 1.9 mg, cheddar 1.5 mg per 42 g, turkey breast 1.5 mg, lentils 1.3 mg per half cup, milk or Greek yogurt about 1 mg, an egg 0.6 mg and a slice of wholemeal bread 0.6 mg. Plant foods contain phytate, which binds zinc, so less of their zinc is absorbed; soaking, sprouting and sourdough fermentation help. A typical Irish meat-eating diet reaches the 10 mg reference value without supplements; a vegetarian or vegan diet often does not, which is why EFSA sets a higher requirement for high-phytate diets.

Is zinc picolinate better than zinc gluconate or citrate?

Not clearly. The best absorption study, by Wegmüller and colleagues at ETH Zurich (Journal of Nutrition, 2014), used stable isotopes in 15 adults and found zinc citrate and zinc gluconate were absorbed equally well (about 61 percent) and zinc oxide less (about 50 percent). The study most often quoted for picolinate, by Barrie and colleagues (Agents and Actions, 1987), gave 15 volunteers 50 mg a day as picolinate, citrate or gluconate for four weeks each and found only picolinate significantly raised hair, urine and red-cell zinc; it is one small, old study using indirect markers and has not been repeated with modern methods. Citrate and gluconate have good direct absorption data, bisglycinate has some encouraging small-study evidence, and oxide showed lower average absorption in one small study, which does not establish poorer outcomes for every use. Evidence does not identify one universally best form; the number of milligrams and your total intake matter more.

Do I need to take copper with zinc?

Not necessarily. Copper deficiency is documented with sustained high zinc intakes; it has not been shown that everyone taking a modest dose needs added copper. Zinc and copper compete for absorption, and high zinc intake induces a gut protein that traps copper, so long-term high-dose zinc can cause copper deficiency, which leads to anaemia and nerve problems. The HSE warns that high doses of zinc reduce the amount of copper the body can absorb. Adults need about 1.2 mg of copper a day, found in shellfish, nuts, seeds, wholegrains and dark chocolate. Jarrow Formulas Zinc Balance pairs 15 mg of zinc with 1 mg of copper for this reason, though added copper does not make a high zinc intake appropriate. Anyone taking more than 25 mg of zinc a day for more than a few months should ask their GP to check copper as well as zinc.

Does zinc help with hair loss?

Zinc contributes to the maintenance of normal hair, which is an authorised EU health claim, and hair thinning is a recognised sign of zinc deficiency. That is different from zinc regrowing hair in someone whose zinc is normal; we did not identify a randomised trial showing that. Hair loss has many causes, including iron deficiency, thyroid problems, hormonal change, stress and genetics, so a GP visit is a better first step than a zinc bottle. If a blood test shows low zinc, your GP can advise on a suitable dose and duration.

What does zinc do for men and does it raise testosterone?

Zinc contributes to the maintenance of normal testosterone levels in the blood and to normal fertility and reproduction; both are authorised EU health claims under Regulation (EU) 432/2012, reflecting that zinc is needed to make testosterone and sperm. In men who are deficient, restoring zinc restores normal production. In men with normal zinc status, we did not identify a randomised trial showing that extra zinc raises testosterone above normal, so zinc is not a testosterone booster. EFSA's reference intake for men is 9.4 to 16.3 mg a day depending on diet, and the 25 mg daily upper limit applies to men as to women.

Is zinc good for acne or skin?

Zinc contributes to the maintenance of normal skin, an authorised EU health claim. For acne specifically, a 2020 systematic review and meta-analysis (Yee et al., Dermatologic Therapy) found that people with acne had lower serum zinc than people without, and that zinc treatment produced a significant reduction in inflammatory papule counts compared with no treatment, with no excess of side effects. An earlier review of studies covering 2,356 patients (Cervantes et al., 2018) found eight of twelve single-agent studies reported benefit, with conflicting results against other treatments. The trials are small and mixed, and the signal is strongest where zinc was low. Zinc is not an acne treatment and is sold in Ireland as a food supplement. If you take lymecycline or doxycycline for acne, take the antibiotic at least 2 hours before or 4 to 6 hours after any zinc supplement, because zinc reduces its absorption.

Can you take zinc with vitamin D, vitamin C, magnesium or iron?

Vitamin D, vitamin C and magnesium can all be taken with zinc; there is no absorption conflict at normal doses, and zinc with magnesium and zinc with vitamin C are common combinations. Iron is the exception: an iron supplement of 25 mg or more taken at the same time reduces zinc absorption, so separate them by a couple of hours (iron in food or fortified cereal does not interfere). Zinc also binds quinolone antibiotics such as ciprofloxacin and tetracyclines such as doxycycline and lymecycline; take those antibiotics at least 2 hours before or 4 to 6 hours after zinc. Separate zinc from penicillamine by at least 1 hour. Time of day does not matter; take zinc with whichever meal you will remember, because on an empty stomach it commonly causes nausea.

Is zinc safe and what are the side effects?

At label doses taken with food, zinc is well tolerated. The usual side effects are nausea, particularly on an empty stomach, a metallic taste, and with lozenges a bad taste in the mouth, reported by 80 percent of users in the Mossad 1996 trial. The 2024 Cochrane review found non-serious side effects 34 percent more common with zinc than placebo and no serious adverse events in treatment trials. Excess intake can cause vomiting, stomach cramps, diarrhoea and headaches, and doses of 50 mg or more a day for weeks can impair copper absorption, reduce immune function and lower HDL cholesterol (NIH Office of Dietary Supplements). The EU upper limit is 25 mg a day from all sources. Zinc sprays or gels used inside the nose were the subject of a 2009 US FDA warning after more than 130 reports of lost sense of smell; zinc by mouth does not carry that risk. The products on this page are for adults aged 18 and over; NOW Foods labels its 50 mg products as not for use in pregnancy or breastfeeding.

Which zinc supplement is best in Ireland?

No single product or form is best for everyone. The EU upper limit of 25 mg a day counts food and supplements together, so what matters is the supplement dose plus your diet: 15 mg (Jarrow Formulas Zinc Balance, which also includes 1 mg copper and is vegan) leaves more room for dietary zinc; 22 mg (Swanson Zinc Picolinate) is close to the limit before food is counted; NOW Foods Zinc Picolinate 50 mg and NOW Foods Zinc 50 mg exceed the limit on their own and are labelled by the manufacturer as not for long-term use. On form, citrate and gluconate have good absorption data, the evidence that picolinate is superior is weak, and oxide was less well absorbed in comparative research. If you plan to take zinc daily for months, check the dose with a pharmacist or GP. All of these are food supplements regulated by the FSAI, carry 13.5 percent VAT in Ireland, and are available from Probiotic.ie with delivery from Dublin.

Related guides

This guide is for educational purposes only and does not constitute medical advice. Jarrow Formulas Zinc Balance, Swanson Zinc Picolinate 22 mg, NOW Foods Zinc Picolinate 50 mg and NOW Foods Zinc 50 mg are food supplements regulated under FSAI guidelines and are not medicines; they are not intended to diagnose, treat, cure or prevent any disease or medical condition, including the common cold, infections, acne, hair loss or low testosterone. Zinc contributes to the normal function of the immune system and to the maintenance of normal skin, hair and nails (authorised EU health claims). Do not take more than 25 mg of zinc a day from supplements unless advised by your GP. Food supplements should not be used as a substitute for a varied, balanced diet. Probiotic.ie is regulated under FSAI food supplement guidelines.

Sources

1. Commission Regulation (EU) No 432/2012 of 16 May 2012 establishing a list of permitted health claims made on foods, other than those referring to the reduction of disease risk and to children's development and health (Annex: 18 zinc claims). — eur-lex.europa.eu CELEX:32012R0432
2. EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA). Scientific Opinion on Dietary Reference Values for zinc. EFSA Journal. 2014;12(10):3844. — efsa.europa.eu/en/efsajournal/pub/3844
3. European Food Safety Authority. Overview on Tolerable Upper Intake Levels as derived by the Scientific Committee on Food (SCF) and the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA). Version 11, 2025. Zinc: 25 mg/day, adults. — efsa.europa.eu ul-summary-report.pdf
4. Food Safety Authority of Ireland, Scientific Committee. The Safety of Vitamins and Minerals in Food Supplements: Establishing Tolerable Upper Intake Levels and a Risk Assessment Approach for Products Marketed in Ireland. Revision 2, 2020. — fsai.ie vitamins and minerals report (PDF)
5. Health Service Executive (HSE). Vitamins and minerals: others (including zinc and copper). — www2.hse.ie/conditions/vitamins-and-minerals/others
6. Kehoe L, Buffini M, McNulty B, Kearney JM, Flynn A, Walton J. The prevalence of inadequate micronutrient intakes and risk of excessive intakes in adults in Ireland: findings from the National Adult Nutrition Survey II. Proc Nutr Soc. 2024;83(OCE4):E424. DOI 10.1017/S0029665124006621. — doi.org/10.1017/S0029665124006621
7. Nault D, Machingo TA, Shipper AG, et al. Zinc for prevention and treatment of the common cold. Cochrane Database Syst Rev. 2024;5:CD014914. DOI 10.1002/14651858.CD014914.pub2. — doi.org/10.1002/14651858.CD014914.pub2
8. Hemilä H. Zinc lozenges and the common cold: a meta-analysis comparing zinc acetate and zinc gluconate, and the role of zinc dosage. JRSM Open. 2017;8(5):2054270417694291. PMID 28515951. — doi.org/10.1177/2054270417694291
9. Hemilä H, Fitzgerald JT, Petrus EJ, Prasad A. Zinc acetate lozenges may improve the recovery rate of common cold patients: an individual patient data meta-analysis. Open Forum Infect Dis. 2017;4(2):ofx059. PMID 28480298. — doi.org/10.1093/ofid/ofx059
10. Hemilä H, Haukka J, Alho M, Vahtera J, Kivimäki M. Zinc acetate lozenges for the treatment of the common cold: a randomised controlled trial. BMJ Open. 2020;10(1):e031662. PMID 31980506. — doi.org/10.1136/bmjopen-2019-031662
11. Mossad SB, Macknin ML, Medendorp SV, Mason P. Zinc gluconate lozenges for treating the common cold: a randomized, double-blind, placebo-controlled study. Ann Intern Med. 1996;125(2):81-88. PMID 8678384. — doi.org/10.7326/0003-4819-125-2-199607150-00001
12. Prasad AS, Beck FWJ, Bao B, et al. Zinc supplementation decreases incidence of infections in the elderly: effect of zinc on generation of cytokines and oxidative stress. Am J Clin Nutr. 2007;85(3):837-844. PMID 17344507. — doi.org/10.1093/ajcn/85.3.837
13. Wessels I, Maywald M, Rink L. Zinc as a gatekeeper of immune function. Nutrients. 2017;9(12):1286. — doi.org/10.3390/nu9121286
14. Wegmüller R, Tay F, Zeder C, Brnić M, Hurrell RF. Zinc absorption by young adults from supplemental zinc citrate is comparable with that from zinc gluconate and higher than from zinc oxide. J Nutr. 2014;144(2):132-136. PMID 24259556. — doi.org/10.3945/jn.113.181487
15. Barrie SA, Wright JV, Pizzorno JE, Kutter E, Barron PC. Comparative absorption of zinc picolinate, zinc citrate and zinc gluconate in humans. Agents Actions. 1987;21(1-2):223-228. — doi.org/10.1007/BF01974946
16. Duncan A, Yacoubian C, Watson N, Morrison I. The risk of copper deficiency in patients prescribed zinc supplements. J Clin Pathol. 2015;68(9):723-725. — doi.org/10.1136/jclinpath-2014-202837
17. Yee BE, Richards P, Sui JY, Marsch AF. Serum zinc levels and efficacy of zinc treatment in acne vulgaris: a systematic review and meta-analysis. Dermatol Ther. 2020;33(6):e14252. PMID 32860489. — doi.org/10.1111/dth.14252
18. Cervantes J, Eber AE, Perper M, Nascimento VM, Nouri K, Keri JE. The role of zinc in the treatment of acne: a review of the literature. Dermatol Ther. 2018;31(1):e12576. — doi.org/10.1111/dth.12576
19. US Food and Drug Administration. Warnings on three Zicam intranasal zinc products. Consumer Update, 16 June 2009 (archived). — fda.gov consumer update (archive)
20. National Institutes of Health, Office of Dietary Supplements. Zinc: Fact Sheet for Health Professionals. Updated 6 January 2026. — ods.od.nih.gov/factsheets/Zinc-HealthProfessional
21. Regulation (EU) No 1169/2011 on the provision of food information to consumers, Annex XIII: nutrient reference values (zinc 10 mg; "significant amount" 15% of NRV per portion). — eur-lex.europa.eu CELEX:32011R1169
22. Revenue Commissioners. Tax and Duty Manual: Food supplement products (VAT treatment). — revenue.ie food supplement products TDM
23. Food Safety Authority of Ireland (FSAI). Food supplements legislation. — fsai.ie/legislation/food-legislation/food-supplements