Potassium is the main mineral inside our cells. It works with sodium, consumed in excess almost everywhere according to the WHO. Here is its role, requirements, food sources, blood pressure evidence and why supplements require caution.
Key takeaways
- Potassium contributes to normal nervous system functioning, normal muscle function and maintenance of normal blood pressure.
- EFSA sets adequate adult intake at 3,500mg daily; dried fruit, vegetables, pulses and potatoes are rich sources.
- Trials show increased potassium intake slightly lowers blood pressure in people with hypertension.
- In kidney disease or with ACE inhibitors, sartans or potassium-sparing diuretics, excess can become dangerous.
What does potassium do?
Potassium is the most abundant positive ion inside cells. The concentration difference between inside and outside, continuously maintained by the sodium–potassium pump, creates membrane electrical potential. This enables nerve impulse transmission and muscle contraction, including heart muscle.
Kidneys finely regulate blood levels: around 90% of consumed potassium is eliminated in urine, the remainder mainly in stools. Regulation is very effective in healthy people, so problems mainly occur when kidneys work poorly. Normal blood levels are between 3.5 and 5.0 mmol/l.
Which claims are authorised for potassium?
Regulation (EU) No 432/2012 authorises three precisely worded claims:
- “Potassium contributes to normal functioning of the nervous system”;
- “Potassium contributes to normal muscle function”;
- “Potassium contributes to the maintenance of normal blood pressure”.
They are restricted to foods at least a potassium “source”, 15% of the 2,000mg nutrient reference value: 300mg per 100 g, or 150mg per 100 ml of a drink. As with vitamin B6, they describe normal roles, not disease effects such as on hypertension.
How much potassium is needed daily?
EFSA set adequate intake at 3,500mg daily for adults including pregnancy, and 4,000mg during breastfeeding. In children it ranges from 800mg at one to three years to 2,700mg at eleven to fourteen, reaching the adult 3,500mg from age fifteen. The WHO considers at least 3,510mg daily potentially beneficial in adults.
Which foods are rich in potassium?
It is mainly found in minimally processed plant foods: dried fruit, vegetables, pulses, potatoes and nuts. Meat, fish and dairy also provide it.
| Food | Potassium (mg per 100 g) | Illustrative serving | Amount per serving |
|---|---|---|---|
| Dried apricots | 1,400 | 30 g | 420mg |
| Roasted pistachios | 1,020 | 30 g | 306mg |
| Prunes | 610 | 30 g | 183mg |
| Baked potato | 535 | 200 g | 1,070mg |
| Pan-fried chicken fillet | 440 | 125 g | 550mg |
| Avocado | 430 | Half (75 g) | 323mg |
| Cooked spinach | 396 | 200 g | 792mg |
| Cooked salmon | 383 | 125 g | 479mg |
| Banana | 320 | 1 fruit (120 g) | 384mg |
| Cooked kidney beans | 300 | 200 g | 600mg |
| Cooked lentils | 222 | 200 g | 444mg |
| Plain yoghurt | 176 | 125 g | 220mg |
Contents: ANSES Ciqual 2020 database. Illustrative servings.
Contrary to popular belief, banana is not the champion: dried apricots contain over four times more by weight. A potato, a serving of spinach, lentils and some dried apricots already supply around 2,700mg: remaining meals make the difference.
Sodium and potassium: why the ratio matters
Potassium and sodium have opposing blood pressure effects. The WHO says increasing potassium can attenuate high salt intake's effects on pressure. Almost every population eats too much salt: global mean sodium intake reached 4,278mg daily in 2021, 11 g salt, over twice the WHO benchmark (below 2,000mg sodium, below 5 g salt).
WHO benchmarks correspond to roughly equal atom numbers: at most 87 mmol sodium and at least 90 mmol potassium. In other words, WHO targets at least as much potassium as sodium. In practice: fewer processed foods, more fruit, vegetables and pulses.
What do blood pressure studies show?
A 2013 meta-analysis pooled 22 randomised trials with 1,606 participants. Increasing potassium intake reduced systolic blood pressure by an average of 3.5 mmHg and diastolic pressure by 2.0 mmHg. This effect occurred in people with hypertension, not in people with normal blood pressure, and reached 7.2 mmHg for systolic pressure with an intake of 90 to 120 mmol per day. No adverse effects on kidney function or blood lipids were observed.
In the same analysis, eleven cohorts (127,038 people) associated high intake with 24% lower stroke risk, without proving causation. In 2020, a thirty-two-trial meta-analysis described a U-shaped curve: benefit plateaus, and very high supplementation was even associated with higher pressure in treated hypertensive people. Other nutrients such as taurine are studied for pressure without an authorised claim.
Salt substitutes: the SSaSS trial
A large trial in 600 rural Chinese villages involved nearly 21,000 people with prior stroke or aged sixty or over with hypertension. They used usual salt or a substitute of 75% sodium chloride and 25% potassium chloride. After an average 4.7 years, substitute use was associated with 14% fewer strokes, 13% fewer major cardiovascular events and 12% fewer deaths.
Serious hyperkalaemia-related adverse effects were not more frequent. However, this is table salt, not a supplement; WHO restricts such substitutes to people without hyperkalaemia risk where healthcare can identify and manage kidney disease.
Hyperkalaemia: when potassium becomes dangerous
Hyperkalaemia is blood potassium above 5.0 mmol/l. It can go unnoticed or threaten life, particularly through heart rhythm disturbances. It mainly occurs when kidneys eliminate poorly, especially affecting:
- people with kidney failure, diabetes or heart disease, and older people more generally;
- people taking medicines slowing potassium elimination: ACE inhibitors, sartans, potassium-sparing diuretics, NSAIDs, trimethoprim or heparin, among others.
Medicines are the leading cause of hyperkalaemia in everyday practice. The US Institute of Medicine advised people on ACE inhibitors, sartans or potassium-sparing diuretics not to take potassium supplements. Heart problems were even described in healthy adults taking 5 to 7 g potassium daily as supplements.
Potassium supplements: the French framework
The French order of 9 May 2006 sets maximum supplemental potassium at 80mg daily. A ministerial reply in May 2025 states these maxima have never changed, though revision is underway. Very little compared with the advised 3,500mg daily: potassium mainly comes from food.
For comparison, Germany's BfR proposes 500mg daily per product maximum. It considers up to 3,000mg supplemental potassium daily seemingly unproblematic in healthy adults, but digestive symptoms have been reported and some preparations linked to small digestive tract lesions. For dosage forms, see capsules, softgels and tablets.
Frequently asked questions
What are signs of low potassium?
Hypokalaemia below 3.5 mmol/l often causes symptoms only below 3.0: weakness, leg cramps, constipation and heart rhythm disturbances. It is less often due to insufficient intake than losses: diuretics, vomiting, prolonged diarrhoea or laxative misuse. It is diagnosed by blood test and corrected under medical supervision.
Is too much blood potassium serious?
It can be: significant hyperkalaemia risks heart rhythm disturbances. It mainly appears with poor kidney elimination, usually severely impaired function, or certain medicines. Abnormal results should be interpreted by a doctor; do not change treatment yourself.
Does potassium help cramps?
True deficiency can cause cramps, but is only one possible cause. These sources do not show a supplement relieving ordinary cramps. Magnesium, often suggested, is discussed in our comparison of magnesium forms.
Is potassium salt suitable for everyone?
No. Potassium-enriched salt substitutes reduce sodium, but increase hyperkalaemia risk in people with poor kidney elimination. With kidney disease, diabetes, ACE inhibitors, sartans or potassium-sparing diuretics, seek medical advice before use.
Why does boiling reduce potassium?
Potassium is water-soluble and partly enters cooking water. Ciqual gives 535mg per 100 g baked potato versus 363mg boiled. To retain it, prefer baking or steaming, or consume the broth.
Does potassium iodide supply potassium?
Very little. In supplements, it supplies iodine at a few tens to hundreds of micrograms: corresponding potassium is negligible. See our article on iodine deficiency and thyroid requirements.
Do athletes need more potassium?
Not specifically. Sweat removes very little; most consumed potassium leaves in urine and around 10% in stools. EFSA's 3,500mg adequate daily intake therefore also applies to active people.
Conclusion
Potassium contributes to normal nervous and muscle function and normal blood pressure. Its best sources are on the plate: dried fruit, potatoes, vegetables, pulses, meat and fish. More potassium and less salt is supported by blood pressure studies. Supplements remain tightly regulated in France and need medical advice with kidney disease or potassium-retaining medication.
Sources
- Commission Regulation (EU) No 432/2012 of 16 May 2012 establishing a list of permitted health claims made on foods. Official Journal of the European Union, L 136, 1-40. eur-lex.europa.eu
- Stone MS, Martyn L, Weaver CM (2016). Potassium Intake, Bioavailability, Hypertension, and Glucose Control. Nutrients, 8(7), 444. doi:10.3390/nu8070444
- EFSA NDA Panel (2016). Dietary reference values for potassium. EFSA Journal, 14(10), 4592. doi:10.2903/j.efsa.2016.4592
- World Health Organization (2026). Healthy diet. Fact sheet. who.int
- World Health Organization (2026). Sodium reduction. Fact sheet. who.int
- Aburto NJ et al. (2013). Effect of increased potassium intake on cardiovascular risk factors and disease: systematic review and meta-analyses. BMJ, 346, f1378. doi:10.1136/bmj.f1378
- Filippini T et al. (2020). Potassium Intake and Blood Pressure: A Dose-Response Meta-Analysis of Randomized Controlled Trials. Journal of the American Heart Association, 9(12), e015719. doi:10.1161/JAHA.119.015719
- Neal B et al. (2021). Effect of Salt Substitution on Cardiovascular Events and Death. New England Journal of Medicine, 385(12), 1067-1077. doi:10.1056/NEJMoa2105675
- Ben Salem C et al. (2014). Drug-induced hyperkalemia. Drug Safety, 37(9), 677-692. doi:10.1007/s40264-014-0196-1
- Kardalas E et al. (2018). Hypokalemia: a clinical update. Endocrine Connections, 7(4), R135-R146. doi:10.1530/EC-18-0109
- BfR, German Federal Institute for Risk Assessment (2021). Proposed maximum levels for the addition of potassium to foods including food supplements. bfr.bund.de
- Order of 9 May 2006 on nutrients permitted in food supplement manufacture (Annex III, maximum daily doses). faolex.fao.org
- French National Assembly (2025). Written question No 3441 on revision of the order of 9 May 2006 and ministerial reply (Official Journal, 20 May 2025). assemblee-nationale.fr
- ANSES. Ciqual 2020 food composition database. ciqual.anses.fr
Food supplements do not replace a varied, balanced diet or a healthy lifestyle. Ask a healthcare professional for advice if you are taking medication, pregnant or breastfeeding.
