Potassium
Potassium in capsules, tablets and electrolyte powders. Find citrate, gluconate and chloride, and see how much elemental potassium each form gives you, why doses stay near 99 mg, and who a top-up genuinely suits.Read more →
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Choosing a potassium supplement in the UK
What potassium does in the body
Potassium is a mineral and an electrolyte, meaning it carries a small electrical charge in body fluid. Almost all of it sits inside your cells, while sodium sits mainly outside them. The push and pull between the two drives nerve signals and muscle contraction. Potassium contributes to normal muscle function, to the normal functioning of the nervous system and to the maintenance of normal blood pressure. In the UK, adults aged 19 to 64 need 3,500 mg a day, and food does most of that work: a jacket potato with the skin, beans, spinach and dried apricots all add up. You will find it next to our other essential minerals.
Why the doses on the label look small
Most potassium capsules and tablets supply around 99 mg of elemental potassium, roughly 3% of the UK daily figure. That is deliberate, not stinginess. Potassium is cleared by the kidneys, so food supplements keep single doses low. Treat a potassium capsule as a small top-up beside food, never as a replacement for vegetables and pulses. Powders work differently: they mix sodium, potassium and magnesium in amounts built for sweat losses, which is why heavy sweaters often do better with electrolyte drinks and powders.
Forms differ in feel, not in magic
Potassium is always bound to another substance: chloride, citrate, gluconate, bicarbonate or aspartate. The label should state the elemental potassium, the part your body counts, not the weight of the whole salt. Citrate and bicarbonate are alkaline salts and sit comfortably with most people. Chloride is the form in salt substitutes and sports blends, and it is the one most often called harsh on an empty stomach. Gluconate is mild but bulky, so capsule counts run higher.
How we pick potassium products
We judge three things: the form, the elemental dose printed on the label, and whether the combination makes sense. For daily use we lean towards citrate and bicarbonate, because they are gentle and clearly declared. Chloride we mostly stock inside electrolyte blends, where it belongs. We pass on products that shout the salt weight in large type and bury the elemental amount in small print. Every item clears our compliance team before it goes live, we test products ourselves, and independent labs spot-check batches. Read how we select brands and products.
Who it suits and who should ask first
A potassium top-up makes most sense if your diet is light on vegetables, pulses and potatoes, if you follow a low-carb or keto plan, or if you train hard and sweat a lot. Many people take it beside a magnesium product, since both minerals leave the body in sweat.
Be realistic about scale. A 99 mg capsule is a nudge, not a correction for a diagnosed deficiency, and that is what the dose is designed for. UK guidance says taking 3,700 mg or less a day from supplements is unlikely to cause harm, while higher amounts can cause stomach pain, nausea and diarrhoea. Older people should not take potassium supplements unless a doctor advises it. The same caution applies if you have kidney problems or take blood pressure medicines such as ACE inhibitors or potassium-sparing diuretics: speak to your GP or pharmacist before you start.
Frequently asked questions
What is potassium and what does it do?
Potassium is an essential mineral and an electrolyte, a mineral that carries a small electrical charge in body fluid. Around 98% of it sits inside your cells, paired against sodium outside them. That balance is what lets nerves send signals and muscles contract and relax. The approved European claims are clear and limited: potassium contributes to normal muscle function, to the normal functioning of the nervous system, and to the maintenance of normal blood pressure.
Do I need a potassium supplement if I eat a normal diet?
Often not. Potassium tracks unprocessed plant foods, so a diet with potatoes in their skins, beans, lentils, leafy greens and fruit usually covers the UK figure of 3,500 mg a day. Supplements make more sense when that pattern is missing: low-carb or keto eating, limited vegetables, or heavy sweating in sport. Even then a capsule is a small addition. If you suspect a genuine deficiency, that needs a blood test, not a shopping decision.
How much potassium do adults need in the UK?
The NHS gives one adult figure and a separate note on supplement amounts.
| Guidance | Amount per day |
|---|---|
| Adults 19 to 64, from food | 3,500 mg |
| From supplements, unlikely to cause harm | 3,700 mg or less |
| Typical single supplement capsule | around 99 mg |
Higher supplement amounts can cause stomach pain, nausea and diarrhoea. These are population reference figures, not personal advice.
Source: NHSWhich form of potassium should I choose?
All forms deliver the same mineral. The difference is how they sit in your stomach and what else they bring.
| Form | Character | Best suited to |
|---|---|---|
| Citrate | Alkaline, gentle | Daily capsule use |
| Bicarbonate | Alkaline, gentle | Sensitive stomachs |
| Gluconate | Mild, bulky | Simple daily top-up |
| Chloride | Salty, can irritate | Electrolyte powders, sport |
Always check the elemental potassium on the label, since that is the amount your body counts.
When is the best time to take potassium?
With a meal and a full glass of water. Food buffers the salt and reduces the chance of a stomach upset, which is the most common complaint with potassium, especially with the chloride form. If you take several capsules across the day, spread them over meals rather than swallowing them together. For sport, an electrolyte powder during or after a long, sweaty session fits better than a capsule, because it also replaces sodium and fluid.
Can I take potassium and magnesium together?
Yes, and many people do, because both minerals leave the body in sweat and both work in muscle and nerve signalling. Take them with a meal to keep digestion comfortable. Keep in mind that they are two separate approved claims and we do not present them as a combined effect. If cramps during training are your reason for looking, browse our products for muscle support and check your fluid and sodium intake too.
Why do potassium tablets only contain 99 mg?
Because supplement doses of potassium are kept deliberately low. Your kidneys regulate potassium tightly, and a large single dose in tablet form is not something a food supplement is meant to deliver. Food spreads potassium across the day in gram amounts; a capsule cannot copy that safely. So 99 mg is a top-up, roughly 3% of the UK daily figure. Electrolyte powders can carry more, because they are dissolved and taken with fluid.
Who should avoid potassium supplements or check with a doctor first?
NHS guidance says older people should not take potassium supplements unless a doctor advises it. The same applies if you have chronic kidney disease or are on dialysis, since damaged kidneys clear potassium poorly. Ask your GP or pharmacist first if you take potassium-sparing diuretics such as spironolactone or amiloride, ACE inhibitors, or angiotensin-receptor blockers, as these can raise blood potassium. Salt substitutes count too: they are largely potassium chloride and add up alongside a supplement.
