What Is Zinc Good For? What It Does, How Much You Need and the Trials

Zinc is good for the work that hundreds of enzymes do every day: in the words a UK label may use, zinc contributes to the normal function of the immune system, to the maintenance of normal skin, hair, nails, bones and vision, to normal cognitive function, to normal fertility and reproduction, to the maintenance of normal testosterone levels in the blood, to normal DNA synthesis and to the protection of cells from oxidative stress.¹ The NHS says you need about "9.5mg a day for men (aged 19 to 64 years)" and "7mg a day for women", that "You should be able to get all the zinc you need from your daily diet", and "Do not take more than 25mg of zinc supplements a day unless advised to by a doctor".² This is the zinc hub within the vitamins and minerals guide, with the wordings and the trial findings in separate tables.

What does zinc do in the body?

An adult body holds 2 to 4 g of zinc, about 0.1% of it in blood plasma; absorption from food ranges from 15 to 60%, and the gut keeps the total steady by absorbing more and losing less when intake falls.³ The UK expert group calls zinc "an essential constituent of more than two hundred metalloenzymes" with "a key role in the synthesis and stabilisation of genetic material", which is why the wordings run from immune cells and skin to bone, the retina, fertility, cognition and metabolism.¹³ There is no large reserve, so intake has to be regular.

What is zinc good for, in the words a UK label may use?

"Only authorised claims in the Great Britain NHC register may be used in Great Britain." These are its eighteen zinc wordings, verbatim, for any food or supplement supplying at least 15% of the 10 mg reference value per portion, each attached to zinc and nothing else.¹

Whether extra zinc changes an outcome is a separate question; doses are elemental zinc, and the grade is this guide's reading, A strongest to D weakest.

What may a UK label not say about zinc?

The register refused zinc wordings for a healthy heart, a healthy prostate, joints, muscular performance, tiredness and fatigue, and mental performance.¹ The MHRA's guide to what counts as a medicine lists "references to all medical conditions including colds, headaches, cuts and bruises" as medicinal claims and states that "Products to treat/prevent or fight spots and acne are medicines as these are adverse medical conditions".¹¹ So this guide reports colds, acne, hair loss and testosterone as trial counts, never as what a supplement is for; the symptom behind each belongs with a GP.

How much zinc do you need, and when is more too much?

9.5 mg a day for men aged 19 to 64 and 7 mg for women; labels use a 10 mg reference value.² The European assessment sets the figure by the phytate in a diet, 7.5 to 12.7 mg for women and 9.4 to 16.3 mg for men, plus 1.6 mg in pregnancy and 2.9 mg when breastfeeding; vegans sit at the top of those ranges.¹² How much zinc a day covers men, women, children, pregnancy and vegans.

The ceiling is the NHS line, "Do not take more than 25mg of zinc supplements a day unless advised to by a doctor", because "Taking high doses of zinc reduces the amount of copper the body can absorb. This can lead to anaemia and weakening of the bones."² The UK expert group reached 25 mg by halving 50 mg a day, the supplemental dose at which zinc "affects iron and copper uptake"; the European committee applied the same 25 mg to pregnant and breastfeeding women.^{3, 13} Count the total across products: a multivitamin plus a vitamin C and zinc tablet can pass 25 mg. Other countries set higher limits. Can you take too much zinc? covers the side effects; zinc and copper explains why the ratio folklore has no trial behind it, and that the NHS says "Having 10mg or less a day of copper is unlikely to cause any harm".²

Who in the UK is short of zinc?

The National Diet and Nutrition Survey found mean zinc intake "above the RNI in all age/sex groups with the exception of girls aged 4 to 10 and 11 to 18 years", a 1 percentage point yearly rise in the proportion of boys aged 11 to 18 and women aged 19 to 64 below the lower reference intake, with the caution that zinc reference values "are based on very limited data".¹⁴ In survey years 7 and 8, zinc intake among girls aged 11 to 14 fell with household income, the lowest-income group consistently taking in less.¹⁵ Across 26 studies, vegetarians took in 0.88 mg a day less zinc and had serum zinc 0.93 µmol/L lower than meat eaters, the gap widest in vegans and women.¹⁶ The UK expert group's deficiency list includes "dermatitis, hair loss, diarrhoea, loss of appetite, loss of taste and smell, anaemia, susceptibility to infections, delayed wound healing"; white spots on the nails are not on it.¹³ Signs of zinc deficiency covers the signs and the blood test; what does zinc do for a woman takes the 7 mg figure through periods, pregnancy and menopause.

Which foods give the most zinc?

From CoFID 2021, the UK composition tables, per 100 g as eaten, portion arithmetic shown.¹⁷

Two eggs a day give about 14% of a man's zinc, 100 g of braised beef all of it, and a vegan plate reaches 7 to 9.5 mg from seeds, nuts, pulses, tofu and wholegrains.¹⁷ Foods high in zinc has the full UK table and vegan sources.

Does zinc help colds, skin, hair, sleep or testosterone?

Colds. The zinc gluconate trials used 45 to 276 mg a day, far above the NHS 25 mg guidance, as short courses started early; colds may be about two days shorter, daily zinc did not prevent them, and side effects were commoner on zinc (RR 1.34).⁴ Zinc contributes to the normal function of the immune system. Does zinc help with colds? walks through the 34 trials, and can you take vitamin C and zinc together the pairing.

Skin. Zinc contributes to the maintenance of normal skin. Acne is a medical condition for a GP or pharmacist; the 332-patient trial above is the trial record, and anyone on a tetracycline antibiotic keeps zinc apart from the dose.⁵ Is zinc good for your skin? has the trials and wound healing.

Hair. Zinc contributes to the maintenance of normal hair. Hair loss is on the UK deficiency list, serum zinc is lower in alopecia areata, and no placebo-controlled trial of zinc alone for hair loss exists.^{6, 13} Does zinc help with hair loss? has the detail.

Sleep. No sleep wording is authorised for zinc. The eight small trials found "no consensus", and the best-known trial, 43 care-home residents, combined zinc with magnesium and melatonin, so its result cannot be attributed to zinc.^{10, 18} Does zinc help you sleep? covers them; which vitamin deficiency affects sleep puts zinc beside iron, vitamin D and magnesium.

Testosterone. Zinc contributes to the maintenance of normal testosterone levels in the blood. The trial record is nine marginally deficient older men with no placebo group, no controlled trial in men who already have enough, and 2,370 couples in whom 30 mg a day did not change live births.^{8, 19} What does zinc do for men? covers testosterone, fertility and the prostate.

Which form of zinc should you look for?

Read the elemental figure: UK labels state the zinc itself, so "zinc 10 mg (as zinc citrate)" means 10 mg of zinc, not the heavier salt weight. The one tracer study of forms gave 15 adults 10 mg of zinc without food: median absorption was 61.3% from citrate, 60.9% from gluconate and 49.9% from oxide, and three of the fifteen absorbed little or none from oxide under those fasting conditions.²⁰ It was a small fasting study of a single dose, untested with meals, and the NHS guidance does not distinguish between forms. Which type of zinc is best? compares picolinate, citrate, gluconate, bisglycinate and oxide; what is zinc picolinate covers its single 1987 study.

What should you not take zinc with?

The NHS says "Iron tablets (such as ferrous sulfate or ferrous fumarate), calcium and zinc supplements can affect ciprofloxacin. Leave 2 hours in between taking supplements and your dose of ciprofloxacin tablets or liquid", and lists "medicines or supplements that contain iron or zinc" among the things that "may not mix well" with doxycycline, so tell your pharmacist.^{21, 22} The BNF states that "Zinc is predicted to decrease the absorption of Penicillamine" and gives no timing, so anyone prescribed it follows their specialist's advice.²⁴ The UK expert group notes that nausea and stomach cramps from zinc salts were "particularly apparent when the supplements were taken with little or no food", so take zinc with a meal.^{3, 13} What should you not take with zinc? has the spacing table; can you take zinc and magnesium together covers the pairing; when is the best time to take zinc covers timing.

When should you see a GP about zinc?

For a persistent rash around the mouth or on the hands, wounds that will not heal, marked hair loss, loss of taste or smell, chronic diarrhoea, or a child growing slowly. Ask before taking a zinc supplement if you are pregnant or breastfeeding (the 25 mg limit applies, and Cochrane found "not enough evidence" of benefit across 25 trials), take any regular medicine, have had gastric surgery or a gut condition, or drink heavily.^{3, 23} The NHS page gives adult figures only; the European upper levels for children run from 7 mg a day at 1 to 3 years to 22 mg at 15 to 17, and a GP, pharmacist or health visitor should advise first.³ Ring 111 out of hours, and 999 for swelling of the face or throat or difficulty breathing.

What we don't know

• How common mild zinc shortfall is in UK adults: plasma zinc is 0.1% of the total, so surveys rest on intake and on reference values the survey itself calls limited.^{3, 14}

Frequently asked questions

Is zinc good for your eyes?

Zinc contributes to the maintenance of normal vision. The AREDS figures in the table come from people who already had macular degeneration, taking 80 mg a day with copper under medical monitoring, more than three times the NHS guidance; healthy eyes were not tested.⁷ Changes in vision need an optometrist or GP.

Does zinc lower blood sugar or reduce belly fat?

Zinc contributes to normal carbohydrate metabolism and normal macronutrient metabolism. The 32 interventions in the table were in people with or at risk of diabetes, a condition a GP manages, and none measured belly fat or weight.⁹ What is berberine has more.

Why do I feel so good after taking zinc?

No trial has measured it. If your intake was low, correcting it can restore appetite and taste over weeks; if it was adequate, the gut absorbs less and loses more to hold the total steady.^{3, 13} Feeling sick after a dose is the commoner report, most often on an empty stomach.¹³

Sources

1. Great Britain nutrition and health claims (NHC) register, zinc entries, 19 May 2026 edition. gov.uk.
2. NHS. Vitamins and minerals: others (zinc and copper). nhs.uk.
3. Scientific Committee on Food. Tolerable upper intake level of zinc, 2003. efsa.europa.eu.
4. Nault D, et al. Zinc for prevention and treatment of the common cold. Cochrane Reviews, 2024. PubMed 38719213.
5. Dreno B, et al. Zinc gluconate versus minocycline in inflammatory acne vulgaris. Dermatology, 2001. PubMed 11586012.
6. Wu R, et al. Serum trace elements and alopecia areata: a meta-analysis. Journal of Cosmetic Dermatology, 2025. PubMed 39739356.
7. Age-Related Eye Disease Study Research Group. AREDS report no. 8. Archives of Ophthalmology, 2001. PubMed 11594942.
8. Prasad AS, et al. Zinc status and serum testosterone levels of healthy adults. Nutrition, 1996. PubMed 8875519.
9. Wang X, et al. Zinc supplementation and glycaemic control: a meta-analysis. American Journal of Clinical Nutrition, 2019. PubMed 31161192.
10. Jazinaki MS, et al. Zinc supplementation and sleep quality: a systematic review. Health Science Reports, 2024. PubMed 39377022.
11. MHRA. Guidance Note 8: a guide to what is a medicinal product, September 2025. gov.uk.
12. EFSA NDA Panel. Dietary reference values for zinc. EFSA Journal, 2014. PubMed 42087959.
13. Expert Group on Vitamins and Minerals. Safe Upper Levels for Vitamins and Minerals, 2003. UK Government Web Archive.
14. Public Health England. National Diet and Nutrition Survey, years 1 to 9: time trend and income analyses, 2019. gov.uk.
15. Thomas M, et al. Income, diet quality and iron and zinc intake in NDNS females aged 11 to 18. European Journal of Nutrition, 2023. PubMed 36149464.
16. Foster M, et al. Effect of vegetarian diets on zinc status: a meta-analysis. Journal of the Science of Food and Agriculture, 2013. PubMed 23595983.
17. Public Health England. Composition of Foods Integrated Dataset (CoFID) 2021. gov.uk.
18. Rondanelli M, et al. The effect of melatonin, magnesium, and zinc on primary insomnia in long-term care facility residents. Journal of the American Geriatrics Society, 2011. PubMed 21226679.
19. Schisterman EF, et al. Folic acid and zinc supplementation in men, semen quality and live birth. JAMA, 2020. PubMed 31910279.
20. Wegmüller R, et al. Zinc absorption from zinc citrate, gluconate and oxide. Journal of Nutrition, 2014. PubMed 24259556.
21. NHS. Taking or using ciprofloxacin with other medicines and herbal supplements. nhs.uk.
22. NHS. Taking doxycycline with other medicines and herbal supplements. nhs.uk.
23. Carducci B, et al. Zinc supplementation for improving pregnancy and infant outcome. Cochrane Reviews, 2021. PubMed 33724446.
24. NICE. British National Formulary: penicillamine, interactions. bnf.nice.org.uk.

This article is general information, not medical advice. A persistent rash, wounds that will not heal, marked hair loss or loss of taste need a GP.