Home › Magnesium Supplements › Magnesium & Potassium Citrate Capsules

Last updated: September 2026

163,000+ verified sales · 5 Star Food Hygiene Rating · Encapsulated and packed in-house in Essex

Key features at a glance

• 480mg potassium per 2 capsules — 24% NRV, more than most capsule products deliver
• 120mg magnesium per 2 capsules — 32% NRV
• 13 authorised UK health claims — 3 for potassium, 10 for magnesium
• Tri-potassium citrate BP grade — min 99% assay, E332(ii)
• Magnesium glycinate 18% — gentler than oxide alone
• 1,000mg fill — the size that makes a real potassium dose possible
• No fillers, binders or flow agents — two minerals and a shell
• Vegan HPMC capsule — no gelatin
• No declarable allergens
• Both minerals declared individually — no proprietary blend
• Encapsulated in-house in Southend-on-Sea, not bought in
• Supplier specification sheets on request
• Six pack sizes 60 · 90 · 120 · 180 · 300 · 500, from £14.99
• 163,000+ verified sales · 5 Star Food Hygiene Rating · UK since 2016

The authorised claims — all thirteen, in register wording

These are the health claims authorised for potassium and magnesium on the GB Nutrition and Health Claims Register. A product may only use them if it supplies at least 15% of the NRV per daily serving. This one supplies 24% and 32%, so every claim below applies. The wording is the register's, not ours.

How potassium and magnesium work

Potassium — the inside-the-cell electrolyte

Potassium is the main positively charged ion inside your cells, and sodium is the main one outside. Every nerve impulse and every muscle contraction — including the heartbeat — depends on potassium and sodium moving across the cell membrane in a controlled way, driven by the sodium-potassium pump. That pump is the basis of the nervous system and muscle function claims. Potassium also helps the kidneys excrete sodium and relaxes the walls of blood vessels, which is the mechanism behind the normal blood pressure claim; a large analysis of controlled trials published in the BMJ found higher potassium intake was associated with lower blood pressure in adults with hypertension (Aburto et al., 2013). Most UK adults get less potassium than the 3,500mg the UK government recommends, largely because processed food is high in sodium and low in potassium.

Magnesium — the cofactor for energy

Magnesium is required by more than 300 enzymes, and above all by every reaction that uses ATP, the molecule cells run on — ATP is only biologically active when bound to magnesium. That is why the register lists energy-yielding metabolism, protein synthesis, cell division and reduction of tiredness and fatigue. Magnesium also regulates calcium flow into muscle and nerve cells, which is the basis of the muscle function, nervous system and psychological function claims, and around 60% of the body's magnesium is stored in bone, hence the bones and teeth claims. A comprehensive physiology review sets out these roles in detail (de Baaij et al., 2015).

Why they belong together

The two minerals are electrolytes that work as a pair. Magnesium is needed to keep potassium inside cells — the sodium-potassium pump itself is magnesium-dependent — so low magnesium makes it harder for the body to hold on to potassium. Both are lost in sweat, both are depleted by some diuretics, and both are low in a typical processed diet. A combined capsule addresses both in one serving without a proprietary blend hiding the ratio.

What is in each capsule

Ingredients: Tri-Potassium Citrate, Magnesium Glycinate (Magnesium Oxide, Glycine), Capsule Shell: HPMC. Nothing else. NRV: potassium 2,000mg, magnesium 375mg.

Why citrate and glycinate

Potassium citrate is the form found in fruit and vegetables and the one used in most supplements. It is well tolerated with food, and because citrate is metabolised to bicarbonate it is mildly alkalising — the opposite of potassium chloride, which is acidifying and more often irritating to the stomach. Ours is BP pharmacopoeia grade at a minimum 99% assay, with sodium capped at 0.3% so it does not undo the point of taking potassium.

Magnesium glycinate pairs magnesium with the amino acid glycine. In this material the magnesium is present as magnesium oxide combined with glycine at roughly a 1:1 ratio, giving 18% elemental magnesium — higher than a fully reacted bisglycinate chelate, which is the trade-off that makes 120mg possible in the space left after the potassium. It is not a fully reacted bisglycinate and we do not call it one. Glycinate forms are generally gentler than oxide alone and are not laxative at this level.

How to take it

1. Two capsules a day with water and food — together, or one with breakfast and one with your evening meal.
2. Do not exceed two. Two is the stated daily intake and there is no benefit in going higher.
3. Check your medication first if you take anything for blood pressure, heart rhythm or fluid retention — see the section below.
4. Sweat a lot? Both minerals are lost in sweat; take the capsules with the meal after training.

Who should check with a doctor first

How it compares

The typical figures are from our own survey of UK listings in September 2026, not a claim about any specific brand. If you only want magnesium, our Magnesium Glycinate 650mg gives more magnesium per capsule; this product is for people who want the potassium.

Where to buy magnesium and potassium capsules UK

You can buy magnesium and potassium citrate capsules UK direct from this page in six sizes, with free UK delivery over £10 and same-day dispatch before 3:30pm Monday to Friday. Direct is the cheapest route and includes the 10% subscription discount. Looking for potassium magnesium capsules UK with the amounts actually declared? Both are on the label, per capsule and per serving. Customer service runs Monday to Friday, 9:00am–3:30pm, on sales@chargeproducts.co.uk.

Related products

• Magnesium Glycinate 650mg Capsules — magnesium only
• Potassium Citrate Pro 900mg — potassium only
• All magnesium supplements
• Sports & performance

Frequently asked questions

How much potassium and magnesium is in each capsule?
Each 1,000mg capsule holds 667mg tri-potassium citrate and 333mg magnesium glycinate, giving 240mg potassium (12% NRV) and 60mg magnesium (16% NRV). Two capsules give 480mg potassium (24% NRV) and 120mg magnesium (32% NRV).

Why potassium citrate rather than potassium chloride?
Citrate is the form used in most potassium supplements because it is better tolerated in the gut and has an alkalising effect on urine, whereas chloride is acidifying. Ours is BP-grade tri-potassium citrate, min 99% assay.

Is the magnesium a bisglycinate?
It is magnesium glycinate, which in this material is magnesium oxide bound with glycine at about a 1:1 ratio. It is not a fully reacted bisglycinate chelate and we do not describe it as one. The elemental magnesium is 18% by weight.

What are the authorised health claims?
Potassium: normal functioning of the nervous system, normal muscle function, maintenance of normal blood pressure. Magnesium: ten authorised claims including reduction of tiredness and fatigue, electrolyte balance, normal muscle function and normal psychological function. All are listed on this page in their register wording.

Does this lower blood pressure?
No claim like that is authorised and we do not make it. The authorised wording is that potassium contributes to the maintenance of normal blood pressure. If you have high blood pressure or take medication for it, speak to your GP before use.

Who should not take it?
Anyone with kidney disease or reduced kidney function, and anyone on ACE inhibitors, ARBs, potassium-sparing diuretics (such as spironolactone or amiloride) or other potassium-raising medicines, unless their doctor has said otherwise. Adults 18+ only.

Is 480mg of potassium a lot?
No. The NRV is 2,000mg a day and a banana contains roughly 400mg. UK safety guidance for supplemental potassium is well above this level. It is more than most capsule products deliver, which is the point of a two-thirds potassium formulation.

When should I take it?
Two capsules a day with water and food, together or split morning and evening. Some people prefer magnesium in the evening; there is no wrong time.

Will it upset my stomach?
Citrate and glycinate are the gentler forms of each mineral. Taking the capsules with food removes most of the risk. Unlike magnesium oxide alone or magnesium citrate at high doses, this combination is not laxative at two capsules.

Is it vegan?
Yes. Both minerals are mineral salts, the capsule is HPMC, and there are no animal-derived ingredients and no declarable allergens.

Why 1,000mg capsules?
Because a 2:1 potassium-to-magnesium blend only reaches a useful potassium level if the capsule is large. A 1,000mg fill gives 480mg potassium in two capsules; a 500mg fill would need four.

Is it made in the UK?
The capsules are filled and packed at our own facility in Southend-on-Sea. The raw minerals are sourced through a UK ingredient distributor with full specification sheets.

Can I get the specification sheets?
Yes. Both raw materials come with supplier specifications covering assay, heavy metals and microbiology, available on request with your order number.

Do you sell it wholesale?
Yes. Trade quantities and white-label capsules are available on request; we encapsulate in-house so we can quote per batch.

How fast is delivery?
Same-day dispatch before 3:30pm Monday to Friday from Southend-on-Sea. Free UK delivery on orders over £10.

What is the returns policy?
Unopened pots can be returned within 30 days. Opened food products are non-returnable for food safety reasons. Damaged on arrival is replaced.

What our customers say

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Food supplement — not a medicine. Not intended to diagnose, treat, cure or prevent any disease. Food supplements should not be used as a substitute for a varied and balanced diet and a healthy lifestyle. Do not exceed the stated daily intake of 2 capsules. Not suitable for under 18s. Not suitable for people with kidney disease or reduced kidney function, or those taking ACE inhibitors, ARBs, potassium-sparing diuretics or other potassium-raising medicines, unless advised by a doctor. Consult your GP before use if pregnant, breastfeeding or taking any medication. Store cool and dry with the lid closed. Keep out of the sight and reach of children. Sold by Big Idea Services Ltd trading as Charge Products, Company No. 11645389, Unit 1, 8 Towerfield Road, Towerfield Industrial Estate, Southend-on-Sea, Essex SS3 9QE. Customer service Monday to Friday, 9:00am–3:30pm UK time.