Potassium
A mineral the body keeps inside its cells, best known for blood pressure.
- Blood pressure
- Topping up levels
- Heart rate
- Bone and calcium
- Blood vessel flexibility
A plain-English overview, not advice. Written from published reviews and trials and from what people say in public forums.
Compare potassium prices per dose
On this page
What is potassium?
Potassium is a mineral, and the most plentiful charged particle inside the body’s cells. Keeping the right amount on each side of the cell membrane is one of the housekeeping jobs every cell depends on, and the kidneys look after it by passing more out in urine when more comes in. Plants need it more than any nutrient but nitrogen, which is how most of it reaches people, through food; as a supplement it is sold as the citrate, the chloride, the gluconate or the bicarbonate.
Why do people take potassium?
Blood pressure
The thinking. Blood pressure sends most people to potassium, and it is what nearly all the research has measured. The thinking is a balance: sodium and potassium pull in opposite directions, so raising one while easing the other should shift where blood pressure settles.
What research has found. Pooled analyses of randomised trials, most four weeks or longer at 30 to 140 mmol a day, found average falls of about four to five mmHg in the upper reading and two to three in the lower. Falls were larger in adults whose readings were already high and in those eating a lot of salt, and smaller in people whose blood pressure was normal. This is one of the best-studied uses, and several reviews of trials broadly agree.
Topping up levels
The thinking. The plainer reason is topping the level up - people who think their diet is short of it, or who have been told their reading is low. Since the kidneys work hard to hold that level steady, the question is whether a supplement moves it at all.
What research has found. One review put twenty trials together - 1,216 adults taking 22 to 140 mmol a day for up to twenty-four weeks. Circulating potassium rose a small but statistically significant amount, around 0.14 mmol per litre, while the amount passed in urine rose far more; the usual marker of kidney function did not change. A fair body of trials has looked at this, and most point the same way.
Heart rate
The thinking. Potassium and the heartbeat are linked in a lot of people’s minds, so a fast or fluttery pulse is another reason it gets picked up. The link is real at the level of the cell: keeping potassium properly spread across the cell membrane is part of how cells work.
What research has found. One review pooled twenty-two placebo-controlled trials in apparently healthy adults, 1,086 people taking a median of 2.5 g a day for about four weeks, and measured resting heart rate. It found no overall difference from placebo, and none in the subgroups it looked at. A reasonable number of trials have measured this, and most of them agree.
Bone and calcium
The thinking. Two of the potassium salts, the citrate and the bicarbonate, are alkaline, and that is why they turn up in bone research. The idea is that an ordinary diet leaves a mild acid load, that calcium from bone helps buffer it, and that an alkaline salt takes the pressure off.
What research has found. Trials in older adults and women past the menopause measured calcium leaving in urine, markers of bone turnover and, in some, bone density. The alkaline salts lowered urinary calcium and one marker of bone breakdown, but not the markers of bone building and not density; a six-month trial in 52 older adults improved calcium balance only at its higher dose. Studies here point in different directions, so this one is still being worked out; the dose, how long people took it and who took part all seem to matter.
Blood vessel flexibility
The thinking. A smaller group take potassium with circulation in mind rather than a number on a cuff. Researchers get at that by measuring how far an artery widens when blood surges through it - a stand-in for how supple a vessel is.
What research has found. Two pooled analyses, covering a few hundred adults between them, do not agree. One found artery widening slightly greater on potassium, under a percentage point on average, and more so where urinary potassium rose most. The other found only the gap between the two blood pressure readings narrowed, and noted how few trials there were. The studies disagree, so this is unsettled: dose, duration and who took part all seem to shift the result.
What does potassium do in the body?
Potassium is not burned like a fuel. It is a charged particle the body keeps mostly inside its cells, and the gap between the amount inside and the amount outside is what cells work against. Keeping that gap steady is the job, and the kidneys are what keep it: when more comes in, more goes out in urine.
That is why the trials read as they do. Weeks of supplements raised the potassium leaving in urine a great deal and the amount circulating in blood only slightly, because the kidneys had absorbed most of the change. It is also why blood pressure and salt are so tangled together here: the trials with the biggest falls were in people eating a lot of salt, starting from a low potassium intake, and not already on blood pressure medicines.
What do people say about taking potassium?
These are anecdotes people have shared, not evidence.
What people like
- Very commonly, night-time leg cramps easing or stopping once potassium went in, usually alongside magnesium rather than on its own.
- Several describe blood pressure readings coming down while taking it, one of them far enough to manage without prescribed tablets.
- A few report numbness, tingling or weakness clearing within a day of starting, the fastest change anyone in these threads describes.
- On low-carb and keto diets it comes up often as part of keeping electrolytes level, with people saying they feel steadier.
Common complaints
- The commonest grumble is how little a shop-bought capsule holds next to the daily target, so food and salt substitutes fill the gap.
- Nearly every thread carries the same caution from other posters: have a blood test first rather than guessing at a dose.
- A few describe unpleasant episodes, including a hard, fast heartbeat after high-dose tablets and one blood level that climbed too high.
- Several say getting enough from food is hard work on a low-carb diet, and that sports drinks carry too little to count.
How people take it
- Hardly anyone takes it alone: magnesium is almost always named alongside it, and often calcium, extra salt or a general electrolyte mix.
- The low-sodium salt substitute, which is mostly potassium chloride, is the route described most often, sprinkled on food or stirred into water.
- Doses described run from one small capsule of about a hundred milligrams up to several tablets a day, usually taken with a meal.
- Many take it in bouts rather than daily: while low-carb dieting, on hot days, on long rides, or after a low blood test.
Read from these public discussions:
- Why potassium and magnesium? (Diabetes.co.uk forum, 2020)
- Do you add salt, magnesium, potassium to your diet? (Diabetes.co.uk forum, 2020)
- What's your experience with Electrolytes (Diabetes.co.uk forum, 2022)
- Do You Have Low Potassium On Low Carb? (Diabetes.co.uk forum, 2018)
- Potassium intake? (Road Bike Review cycling forum, 2007)
What forms of potassium are there?
| Form | What’s different | Elemental potassium by weight | Per serving, on products we list |
|---|---|---|---|
| Citrate | Potassium joined to citrate, an alkaline salt, and the form used in most of the bone research. | about 36.2 % | not in our price tables yet |
| Chloride | Potassium joined to chloride, which is not alkaline; it carries the most potassium for its weight. | about 52.4 % | 1 g |
| Gluconate | Potassium joined to gluconate, a bulkier carrier, so a capsule holds less potassium for its weight. | about 16.7 % | not in our price tables yet |
| Other forms | Bicarbonate is the other alkaline salt studied for bone; unspecified means the label names no salt. | stated on the label | not in our price tables yet |
What else is worth knowing about potassium?
- Labels give the amount per serving, and a serving may be more than one capsule; the salts differ too, so prices here are lined up as elemental potassium.
- One review of the pooled trials reported no important adverse effects, and another found circulating potassium rose only slightly while the usual marker of kidney function was unchanged.
- The reviews raise one caution themselves: in a dose-response analysis the blood pressure difference weakened at higher intakes and reversed at the highest, mainly in adults already on blood pressure medicines.
If you take medication, are pregnant, or have a health condition, check with a pharmacist or GP first.
The research behind this page (18 studies)
- Magnesium and Potassium Supplementation for Systolic Blood Pressure Reduction in the General Normotensive Population: A Systematic Review and Subgroup Meta-Analysis for Optimal Dosage and Treatment Length. (2024, meta-analysis)
- Potassium Intake and Blood Pressure: A Dose-Response Meta-Analysis of Randomized Controlled Trials. (2020, meta-analysis)
- The effect of potassium supplementation on blood pressure in hypertensive subjects: A systematic review and meta-analysis. (2017, meta-analysis)
- Oral potassium supplementation for management of essential hypertension: A meta-analysis of randomized controlled trials. (2017, meta-analysis)
- Daily potassium intake and sodium-to-potassium ratio in the reduction of blood pressure: a meta-analysis of randomized controlled trials. (2015, meta-analysis)
- Systematic review and meta-analysis of randomised controlled trials on the effects of potassium supplements on serum potassium and creatinine. (2016, meta-analysis)
- Potassium supplementation and heart rate: A meta-analysis of randomized controlled trials. (2016, meta-analysis)
- Effects of Potassium Citrate Supplementation on Bone Turnover Markers in Postmenopausal Women: A GRADE-Assessed Systematic Review, Meta-analysis and Trial Sequential Analysis. (2026, meta-analysis)
- The effect of supplementation with alkaline potassium salts on bone metabolism: a meta-analysis. (2015, meta-analysis)
- Potassium citrate supplementation results in sustained improvement in calcium balance in older men and women. (2013, randomised trial)
- Effect of Potassium Supplementation on Endothelial Function: A Systematic Review and Meta-Analysis of Intervention Studies. (2023, meta-analysis)
- Effect of potassium supplementation on vascular function: A meta-analysis of randomized controlled trials. (2017, meta-analysis)
- Cardiac potassium channel subtypes: new roles in repolarization and arrhythmia. (2014, review)
- The First-in-Class Potassium-Competitive Acid Blocker, Vonoprazan Fumarate: Pharmacokinetic and Pharmacodynamic Considerations. (2016, review)
- Potassium Intake, Bioavailability, Hypertension, and Glucose Control. (2016, review)
- Potassium: From Physiology to Clinical Implications. (2016, review)
- Potassium-Enriched Salt Substitutes: A Review of Recommendations in Clinical Management Guidelines. (2024, review)
- Achieving the Benefits of a High-Potassium, Paleolithic Diet, Without the Toxicity. (2016, review)
How much does potassium cost?
That depends on the form and the pack, so we work out the price of the same dose of every potassium product we can find and rank them.