Also known as: Potassium citrate, Potassium chloride, Potassium gluconate, K
MineralsStrong evidence
The main mineral inside cells, working opposite sodium to run nerve signals and muscle contraction. Most people fall short, and supplements are legally capped at a fraction of requirement — which tells you something.
Typical dose
200.0–3500.0 mg per day
Through food across the day; supplements are capped too low to matter much
What it is
Potassium is the principal mineral inside cells, as sodium is outside them. The gradient between the two is what makes nerve signalling and muscle contraction possible.
Requirements are large by mineral standards — around 3,500 mg daily for adults — and most people in the UK fall short. This is a food problem rather than a supplement one, since the shortfall reflects low fruit and vegetable intake.
Here is the detail worth knowing before buying: potassium supplements are legally restricted in the UK to a small amount per daily dose, far below requirement. A potassium tablet therefore supplies a tiny fraction of what you need. That restriction exists for good reason, and it means supplements cannot meaningfully close a dietary gap. A banana supplies more than a typical tablet.
How it works
The sodium-potassium pump maintains a difference in charge across every cell membrane in the body, using a substantial share of resting energy expenditure to do it. That gradient is what nerve impulses and muscle contractions actually run on.
Potassium also counterbalances sodium in blood pressure regulation. Raising potassium intake tends to lower blood pressure, and the ratio between the two matters more than either figure alone.
It additionally supports glycogen storage in muscle, which is why potassium and water shift together during carbohydrate loading and depletion.
What the evidence shows
Potassium's essentiality is beyond dispute. The evidence that higher dietary potassium intake is associated with lower blood pressure is strong and consistent across observational and interventional research.
Most of that evidence concerns potassium from food rather than supplements, which fits neatly with the fact that supplements are capped so low.
For cramping during exercise, the popular association with potassium is weaker than folk wisdom suggests. Cramp is more closely tied to neuromuscular fatigue than to any single mineral, and the banana-for-cramp idea has not held up well under testing.
Dosing
Adult requirement is around 3,500 mg daily. Supplements in the UK are limited to a small fraction of that per daily dose, so they cannot fill the gap.
The practical answer is food. Potatoes, beans, lentils, leafy greens, bananas, dried fruit, avocado, fish and dairy all contribute meaningfully. A jacket potato supplies over 1,000 mg.
Low-sodium salt substitutes are potassium chloride and can raise intake substantially, but they are not appropriate for everyone — anyone whose kidney function is being monitored should check before using them, because they can raise potassium more than expected.
At a glance
Common forms
Potassium citrate, Potassium chloride, Potassium gluconate, Low-sodium salt substitutes, Within electrolyte drinks
Half-life / duration
Tightly regulated by the kidneys hour to hour
Timing
Through food across the day; supplements are capped too low to matter much
Competition status
Permitted — not on the WADA Prohibited List
Category
Minerals
Safety and side effects
Potassium from food is safe for people with normal kidney function, because the kidneys regulate blood levels tightly and excrete what is not needed.
High-dose potassium supplements are a different matter, and this is precisely why they are legally restricted. Where kidney function is reduced, or where medication affects potassium handling, levels can rise dangerously, and that affects the heart directly.
Anyone whose kidney function is being monitored, or who takes regular medication, should check before using potassium supplements or low-sodium salt substitutes. Supplements can also cause digestive irritation.
Who should avoid it
Do not use potassium supplements or low-sodium salt substitutes if you have been told your kidneys are not working normally, or if you take regular medication, without checking with your doctor first — potassium levels affect the heart directly. Get potassium from food where possible. May cause digestive irritation in supplement form.
This entry is provided for information only. Food supplements should not be used as a substitute for a varied and balanced diet and a healthy lifestyle. Consult a qualified healthcare professional before use if you are pregnant, breastfeeding, taking medication or under medical supervision.
