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Zinc supplements in the UK: picolinate vs gluconate vs citrate

August 20, 2026

zinc is sold in at least six chemical forms in the UK and the packaging rarely explains what separates them. This guide covers how much actual zinc each form contains, what has been measured about absorption, what a label may legally claim, and how to compare two tubs on price.

What UK guidance says about zinc

The NHS puts the amount of zinc adults need at "9.5mg a day for men (aged 19 to 64 years)" and "7mg a day for women", and states that most people "should get all the nutrients they need by having a varied and balanced diet, although some people may need to take extra supplements".

There is also a ceiling. The NHS says that "taking high doses of zinc reduces the amount of copper the body can absorb", which "can lead to anaemia and weakening of the bones", and advises: "Do not take more than 25mg of zinc supplements a day unless advised to by a doctor." That 25mg figure is worth carrying around a shop, because plenty of products on sale sit at or above it.

The percentage on the pack is a different reference point. UK labels express content against the nutrient reference value, and retained Regulation 1169/2011 sets the NRV for zinc at 10mg, so "150% NRV" means 15mg. Read the milligrams, not the percentage.

What a zinc label is allowed to claim

Zinc is one of the nutrients that has authorised health claims, so a British pack can say specific things without stepping outside the law. The Great Britain Nutrition and Health Claims Register, maintained by the Department of Health and Social Care, lists 18 authorised zinc claims, including "Zinc contributes to the normal function of the immune system", "Zinc contributes to normal DNA synthesis" and "Zinc contributes to the maintenance of normal skin". Those are the authorised wordings and a brand may use them or a form with the same meaning for the consumer.

The condition attached to every one of them is only that the product is at least a source of zinc, which the register puts at 15% of the NRV, roughly 1.5mg per portion. Almost every zinc supplement clears that, so the claim on the front tells you nothing about how the product compares with the one next to it.

The register is also a list of refusals, and that half is more useful. "Zinc for a healthy prostate", "Zinc contributes to a healthy cardiovascular system" and "Zinc promotes joint health" are all recorded as Non-authorised. Wording close to any of those means a claim that was assessed and turned down, not one that was overlooked. Northern Ireland follows the EU register, so the GB list applies to England, Scotland and Wales.

The three forms, and what actually separates them

Elemental zinc: the number often left off the front

Zinc picolinate, gluconate and citrate are zinc bound to an organic acid, and the acid is most of the weight. Worked out from the molecular weights recorded by PubChem, picolinate is about 21% zinc, gluconate about 14%, and anhydrous citrate about 34%. Hydrated citrate grades sit a little lower.

So 15mg of elemental zinc needs roughly 71mg of zinc picolinate, 105mg of zinc gluconate or 44mg of zinc citrate. A pack advertising "50mg zinc gluconate" is offering about 7mg of zinc; a pack advertising "50mg zinc" should be offering 50mg. The two look near identical on a shelf. A clear label states the elemental figure, usually as "zinc (as zinc citrate) 15mg".

Absorption: what has been measured

The head-to-head data is thinner than the marketing suggests. The most direct comparison is Wegmüller and colleagues in the Journal of Nutrition in 2014, a randomised, double-masked, three-way crossover in 15 healthy adults using stable isotope tracers. Median fractional absorption was 61.3% from zinc citrate and 60.9% from zinc gluconate, a difference the authors described as no difference, while zinc oxide came in at 49.9%, significantly lower than both. Three participants absorbed little or nothing from the oxide.

Picolinate was not in that trial. The case for it rests largely on Barrie and colleagues in Agents and Actions in 1987, a double-blind four-period crossover in 15 volunteers taking the equivalent of 50mg of elemental zinc daily for four weeks. Hair, urine and erythrocyte zinc rose during the picolinate period and did not change significantly on gluconate, citrate or placebo. That is a real result, but it is one small study from 1987, it used indirect status markers rather than isotope tracers, and it has not been repeated at scale in the four decades since. The honest summary is that citrate and gluconate have been shown to be equivalent to each other and better than oxide, and that picolinate's advantage is plausible and poorly evidenced.

All three are permitted in the UK

A recurring myth is that picolinate is unapproved here. It is not. Retained Directive 2002/46/EC, Annex II, which sets the mineral forms permitted in food supplements in Great Britain, lists zinc picolinate, zinc citrate and zinc gluconate alongside zinc oxide, zinc sulphate and zinc bisglycinate. Form is a content and price question, not a legality one.

How to work out what you are actually paying

Compare cost per milligram of elemental zinc, not cost per tub or per capsule. Divide the pack price by the number of capsules, then by the elemental zinc per capsule. A 90-capsule tub at £9 with 15mg per capsule is 0.67p per milligram. A 120-capsule tub at £11 with 7mg per capsule is 1.31p per milligram, roughly twice as much, despite the bigger pack. Low-elemental gluconate products tend to lose on this measure.

Cautions worth naming

The Summary of Product Characteristics for Solvazinc, a licensed UK zinc sulfate preparation, names the interactions specifically. It records that zinc may inhibit copper absorption; that zinc and tetracycline antibiotics each reduce the other's absorption, with an interval of at least three hours recommended when both are taken; that zinc may reduce absorption of the quinolones ciprofloxacin, levofloxacin, moxifloxacin, norfloxacin and ofloxacin; that calcium salts and oral iron reduce zinc absorption, with zinc reducing oral iron absorption in turn; and that zinc and penicillamine, and zinc and trientine, each reduce the other's absorption. If any of those are in your cupboard, that is a conversation for your GP or pharmacist.

What we stock

Zinc from established brands sits in our vitamins and minerals range, with the form and elemental content on each listing so the per-milligram comparison above is possible without a magnifying glass. Everything is sourced through PowerBody, an authorised EU distributor.

Membership costs £4.99 a month or £29.99 a year and unlocks member pricing across the whole catalogue. Details are on the membership page.

Related reading

This article reports published news and research and is for information only. Food supplements are not a substitute for a varied diet or medical care, and no product mentioned is intended to diagnose, treat, cure or prevent any disease. Speak to your GP or pharmacist before changing what you take, especially if you are pregnant, breastfeeding, or taking prescribed medicines.

Sources

Originally reported by the NHS and the Department of Health and Social Care. This article has been reviewed by Dr Tosin.

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