Which Type of Zinc Is Best? Picolinate, Citrate, Gluconate and Oxide

No type of zinc has been shown in a trial to do more for your health than another. The forms differ in how much zinc they carry by weight and, in one small fasting study of 15 adults, in the share absorbed, but no study has linked any form to a better outcome.¹ The NHS says you need "about: 9.5mg a day for men (aged 19 to 64 years), 7mg a day for women", and "Do not take more than 25mg of zinc supplements a day unless advised to by a doctor".² All seven forms are permitted in Great Britain.³ Part of the Wellgard zinc guide and the vitamins and minerals guide.

Sources checked on 30 October 2026.

What are the different types of zinc?

The second word on the label names the partner zinc is bound to. Picolinate, citrate, gluconate and acetate are zinc bound to picolinic, citric, gluconic and acetic acid. Bisglycinate, also sold as glycinate or "chelated zinc", is zinc held between two molecules of the amino acid glycine. Sulphate is a mineral salt, the form many older trials used. Oxide is zinc and oxygen alone, the most concentrated form, dissolving in stomach acid rather than water. Sixteen zinc compounds are permitted in Great Britain, lactate, malate and pidolate among them.³

How do the forms compare?

The table is alphabetical. Zinc per 100 mg is calculated from formula weights and shifts with crystal water; use the label's figure.

What did the absorption study actually find?

In a supplier-funded 2014 study, 15 healthy adults took 10 mg of zinc as citrate, gluconate and oxide, without food, in a randomised crossover with isotope tracers.¹ Median absorption was 61.3% from citrate, 60.9% from gluconate and 49.9% from oxide; citrate and gluconate did not differ, oxide was lower (P < 0.01), and three of the 15 absorbed little or no zinc from oxide. The authors confined their conclusion to oxide "given as a supplement without food", and no form was tested with a meal.¹ As a dose rises the percentage absorbed falls while the total absorbed still rises.⁶

What is the evidence for zinc picolinate?

One study from 1987. Fifteen volunteers took picolinate, citrate, gluconate (50 mg of zinc a day) and placebo for four weeks each.⁵ Hair, urine and red-cell zinc rose significantly on picolinate and did not change on the others; serum zinc did not change on any. That is indirect status markers in 15 people, at twice the NHS supplement line, never repeated with the isotope method. See what is zinc picolinate.

What about bisglycinate, glycinate and "chelated" zinc?

Bisglycinate and glycinate are the same compound, and "chelated" describes the bond to glycine, not a result. The evidence is one study: 12 healthy women took a single 15 mg dose as bisglycinate and as gluconate, a week apart; measured from serum zinc, bioavailability was 43.4% higher after bisglycinate, and both were well tolerated.⁴ One dose and one blood curve in 12 people. No absorption comparison is an authorised claim for any form, so no label may make one.

What are zinc sulphate and zinc acetate used for?

Sulphate shows why salt weight misleads: in one trial 220 mg of zinc sulphate supplied 50 mg of zinc.⁷ Acetate and gluconate are the lozenge forms. In the 2024 Cochrane review of 34 trials in 8,526 people, zinc taken once a cold had started may have shortened it by about 2.4 days (low certainty), with more side effects such as an unpleasant taste and stomach upset; zinc gluconate was given at 45 to 276 mg a day for 4.5 to 21 days.⁸ Across seven trials at more than 75 mg a day, acetate and gluconate did not differ significantly.⁹ Those are short trial courses at several times the NHS 25 mg line; no daily zinc supplement is a cold remedy, and the lawful wording is that zinc contributes to the normal function of the immune system. See does zinc help with colds.

Does the form change side effects?

Nausea with zinc is about the dose and an empty stomach, not the salt. In a six-week trial of 47 volunteers taking 150 mg of zinc a day as sulphate, symptoms from headaches to vomiting were reported by 84% of the women and 18% of the men.⁷ The UK Expert Group on Vitamins and Minerals found them "particularly apparent when small meals or no food was taken with the supplements".¹⁰ Copper depends on total zinc, not the form: the NHS says "Taking high doses of zinc reduces the amount of copper the body can absorb. This can lead to anaemia and weakening of the bones"; the Expert Group placed the effect at supplemental doses of 50 mg a day and above^{2, 10} (see can you take too much zinc).

How do you read a zinc label?

1. Find the elemental figure. UK labels state the mineral, so "zinc (as zinc citrate) 10 mg" means 10 mg of zinc; "zinc gluconate 50 mg" alone is about 7 mg of zinc.
2. Read the % NRV. The reference value is 10 mg, so 150% is 15 mg and a "high strength" 25 mg tablet is 250%, the whole NHS allowance.^{2, 13}
3. Add up every product that contains zinc; two together can pass 25 mg. How much zinc a day gives the UK amounts by group.
4. Take it with a meal if zinc has ever made you feel sick, and space it from medicines: ciprofloxacin tablets' prescribing information says to take the antibiotic "either 1-2 hours before or at least 4 hours after" mineral supplements (zinc salts included, says the Expert Group); the NHS lists zinc supplements among things that "may not mix well" with doxycycline; tell your pharmacist, as with penicillamine.^{10, 11, 14} Iron at two or three times the zinc dose, swallowed together, substantially reduced zinc uptake.¹² In pregnancy, breastfeeding and for children, stay within the NHS amounts and ask a GP, midwife or pharmacist.² See what should you not take with zinc.

The wording a label may carry is the same for every form, for example "Zinc contributes to the normal function of the immune system" and "Zinc contributes to the maintenance of normal skin".¹⁵ Symptoms belong with a GP: see signs of zinc deficiency; vitamin C and zinc together covers the commonest pairing.

What we don't know

Whether the oxide gap holds with food, at daily label doses, or changes anything a person would notice: the one tracer comparison was 15 fasting adults on single 10 mg doses, and picolinate and bisglycinate have never been through the isotope method.^{1, 4, 5} Whether any form is easier on the stomach at label doses: the comparison studies did not report nausea as an outcome, so the evidence supports a meal rather than a form.^{7, 10}

Frequently asked questions

What is zinc carnosine?

Zinc bound to the dipeptide carnosine. A "gastric comfort" wording for it is non-authorised on the Great Britain nutrition and health claims register, so no label may make it.¹⁵ No study compares its absorption with the other forms; digestive symptoms are for a GP or pharmacist.

Is it better to take zinc glycinate at night or in the morning?

No trial compares times of day for any form (when is the best time to take zinc; does zinc help you sleep). Take it with a meal if it has upset your stomach, at a different time from an iron tablet, and spaced from ciprofloxacin as its prescribing information says.^{11, 12}

Is zinc oxide safe, and is it banned?

It is on the permitted list for food supplements in Great Britain.³ In the one fasting study it was absorbed less than citrate and gluconate, and it was not tested with food.¹

Sources

1. Wegmüller R, et al. Zinc absorption from zinc citrate, gluconate and oxide. Journal of Nutrition, 2014. Randomised crossover tracer study, 15 adults, single 10 mg doses without food; supplier-funded (a zinc citrate manufacturer). PubMed 24259556.
2. NHS. Vitamins and minerals: others (zinc and copper). Page last reviewed 3 August 2020 (review overdue). nhs.uk.
3. Directive 2002/46/EC on food supplements, Annex II, as retained in Great Britain. Regulation. legislation.gov.uk.
4. Gandia P, et al. Bioavailability of zinc bis-glycinate versus zinc gluconate after a single dose in twelve healthy women. International Journal for Vitamin and Nutrition Research, 2007. Randomised crossover, 12 women, single 15 mg doses; funding not stated on PubMed. PubMed 18271278.
5. Barrie SA, et al. Comparative absorption of zinc picolinate, zinc citrate and zinc gluconate in humans. Agents and Actions, 1987. Double-blind crossover, 15 volunteers, 50 mg a day for four weeks per form; public or charity funding listed on PubMed. PubMed 3630857.
6. King JC. Does zinc absorption reflect zinc status? International Journal for Vitamin and Nutrition Research, 2010. Narrative review; funding not stated on PubMed. PubMed 21462113.
7. Samman S, Roberts DC. Zinc supplements, plasma zinc and copper, and reported symptoms in healthy volunteers. Medical Journal of Australia, 1987. Double-blind crossover, 47 volunteers, 150 mg a day for six weeks; public or charity funding listed on PubMed. PubMed 3547053.
8. Nault D, et al. Zinc for prevention and treatment of the common cold. Cochrane Database of Systematic Reviews, 2024. Systematic review, 34 randomised trials, 8,526 people; no conflicts declared. PubMed 38719213.
9. Hemilä H. Zinc lozenges and the common cold: zinc acetate versus zinc gluconate, and dosage. JRSM Open, 2017. Meta-analysis, 7 placebo-controlled trials, 575 people; funding not stated on PubMed. PubMed 28515951.
10. Expert Group on Vitamins and Minerals. Safe Upper Levels for Vitamins and Minerals, 2003. Expert committee report. UK Government Web Archive.
11. Ciprofloxacin 500 mg film-coated tablets. Summary of Product Characteristics (licensed product information), section 4.5, revised 29 May 2026. medicines.org.uk.
12. Solomons NW, Jacob RA. Effects of heme and nonheme iron on the absorption of zinc in humans. American Journal of Clinical Nutrition, 1981. Plasma zinc response study in volunteers; funding not stated on PubMed. PubMed 7223699.
13. Retained Regulation (EU) No 1169/2011, Annex XIII, nutrient reference values. Regulation. legislation.gov.uk.
14. NHS. Doxycycline. Page last reviewed 5 September 2025. nhs.uk.
15. Great Britain nutrition and health claims (NHC) register, zinc entries. Updated 19 May 2026. gov.uk.

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This article is general information, not medical advice. Keep supplemental zinc under 25 mg a day unless a doctor advises otherwise, tell your pharmacist about zinc if you take medicines, and see a GP about symptoms.