Potassium: Roles, Food Sources, Supplements and Kidney/Medicine Cautions
Potassium's roles, food sources, official intake levels by country, evidence on blood pressure, and why kidney disease and some medicines make extra potassium risky.
Content last updated . This page has not been medically reviewed.
What is Potassium good for?
What the body uses it for, and how strong the evidence is. A normal job in the body is not proof that extra supplements add benefit; each card says which.
Fluid balance
Established rolePotassium helps control the balance of fluids in the body.
Supplements: Needed from food; no source read shows extra supplements add benefit when intake is adequate.
Heart muscle and heartbeat
Established rolePotassium helps the heart muscle work properly and keep a regular heartbeat.
Supplements: Supplements are used to treat low potassium under medical care; too much is dangerous.
Muscle contraction
Established rolePotassium is needed for muscles to contract. Low levels can cause cramps and weak or twitching muscles.
Supplements: Helps when levels are low; not shown to help when levels are normal.
Nerve function
Established rolePotassium supports nerve function.
Supplements: Matters mainly when levels are abnormal.
Moving nutrients into cells and waste out
Established rolePotassium helps move nutrients into cells and waste products out.
Supplements: Needed from food; no evidence of added benefit from supplements at adequate intake.
Offsetting sodium's effect on blood pressure
Preliminary or mixedA potassium-rich diet can help offset some of the effect of sodium on blood pressure.
Supplements: Evidence relates to food and lower-sodium salt substitutes; not to potassium pills. Salt substitutes are not safe for people with kidney disease.
Connected topics
Open a group to see how each topic connects and how strong the evidence is.
Health goals (2)
- Blood Pressure SupportPreliminary or mixed
A potassium-rich diet can help offset sodium's effect on blood pressure. We did not read trial data on potassium pills.
- Heart HealthEstablished role
Potassium is needed for a normal heartbeat. Extra supplements are not shown to improve heart health in people with normal levels, and too much is dangerous.
Body systems (7)
- Cardiovascular SystemEstablished role
Potassium helps the heart muscle work properly and keep a regular heartbeat. Blood levels that are too high or too low can cause abnormal heart rhythms.
- Heart & CirculationEstablished role
Potassium helps the heart muscle work properly and keep a regular heartbeat.
- Kidney & UrinaryDocumented risk
Healthy kidneys keep potassium in balance. In chronic kidney disease they may not clear extra potassium, so intake may need to be limited.
- Nervous SystemEstablished role
Potassium supports nerve function. Low or high blood potassium can cause weakness, tingling or numbness.
- Bones, Joints & MusclesEstablished role
Potassium is needed for muscle contraction. Low levels can cause cramps and weak or twitching muscles.
- Musculoskeletal SystemEstablished role
Potassium is needed for muscle contraction. Low levels can cause cramps and weak or twitching muscles.
- Urinary SystemDocumented risk
The kidneys regulate blood potassium. When they work less well, potassium can build up.
Body parts (5)
- HeartEstablished role
Potassium helps the heart muscle work properly. Too much or too little can disturb heart rhythm.
- KidneysDocumented risk
The kidneys remove extra potassium. With kidney disease, potassium can build up in the blood.
- MusclesEstablished role
Potassium supports muscle contraction; low levels are linked to cramps and weakness.
- CellsEstablished role
Potassium helps move nutrients into cells and waste products out.
- Nervous SystemEstablished role
Potassium supports nerve function.
Functional actions (3)
- Hydration SupportEstablished role
Potassium helps control the balance of fluids in the body. It does not replace drinking enough fluid.
- Cardiovascular SupportEstablished role
Potassium helps the heart muscle work properly. Diet-based intake is the supported route; supplement pills for heart health are not shown to help healthy people.
- Nervous System SupportEstablished role
Potassium supports nerve function as part of normal body chemistry.
Root causes (3)
- Medication Side EffectsDocumented risk
Some medicines, including diuretics, can lower or raise blood potassium. Ask a pharmacist or prescriber before changing anything.
- Nutrient DeficiencyDeficiency link
Low blood potassium can cause cramps, weakness and irregular heartbeat. It is usually caused by diuretics, vomiting, diarrhoea or other illness, not by diet alone.
- DehydrationDeficiency link
Fluid loss from diarrhoea, vomiting or heavy sweating is a listed cause of low blood potassium.
Habits (1)
- Balanced NutritionEstablished role
The NHS says a varied, balanced diet should supply all the potassium most people need.
Biomarkers (1)
- CreatinineDocumented risk
Kidney function tests are used alongside potassium because kidney disease can cause potassium to build up. This is a context link, not a measure of potassium.
Conditions & symptoms (6)
- Cardiac ArrhythmiaDocumented risk
Irregular heartbeat is a symptom of both low and high blood potassium.
- HyperkalemiaDocumented risk
High blood potassium can cause irregular heartbeat, weakness and tingling. Causes include kidney disease, Addison disease and some medicines; very high intake from diet or supplements is uncommon.
- HypokalemiaDeficiency link
Low blood potassium causes irregular heartbeat, cramps, weak or twitching muscles, fatigue and constipation. It is usually caused by diuretics, fluid loss, laxatives, adrenal or kidney disease or alcohol use disorder, rarely by diet alone.
- Potassium DeficiencyDeficiency link
Another name for low potassium; needs a blood test, not symptom-based guessing.
- Muscle CrampDeficiency link
Cramps are a listed symptom of low potassium, but most cramps have other causes.
- Muscle WeaknessDeficiency link
Weak muscles are a symptom of both low and high blood potassium.
Documented risks and interactions (2)
- Kidney regulation of potassium. Healthy kidneys keep blood potassium in balance by removing the extra.
- Medicine effects on potassium. Some medicines raise or lower blood potassium; diuretics are linked to low potassium.
What potassium does
The NHS says potassium helps control fluid balance and helps the heart muscle work properly. [3] MedlinePlus adds muscle function and acid-base balance. [1] This is an established nutritional role. Evidence labels below say how strong the support is; Proper evidence not found means we looked and found nothing usable.Food sources
Vegetables and fruit are the richest sources, including beans, lentils, tomatoes, potatoes with the skin, winter squash, citrus fruit, cantaloupe, bananas, kiwi and apricots. [1] Milk, yogurt and nuts are also good sources, and meat and fish give some. [1] EFSA lists starchy roots, vegetables and fruit, whole grains, dairy products and coffee. [4] The NHS says you should be able to get all the potassium you need from a varied, balanced diet. [3] Lists and low-potassium swaps are on Foods high in potassium.Official intake levels
These are published levels for healthy groups, not targets for people with kidney disease. They are expressed as milligrams of potassium (mg), not of a potassium salt.| Body, country and year | Group | Level |
|---|---|---|
| NHS, UK (page reviewed 2020) | Adults 19 to 64 | 3,500 mg a day [3] |
| EFSA, EU (adequate intake, 2016) | Adults including pregnant women | 3,500 mg a day [4] |
| EFSA, EU (2016) | Lactating women | 4,000 mg a day [4] |
| US National Academies intakes as listed by MedlinePlus (reviewed 2026; page does not say AI or RDA) | Men and women 19 and older | 3,400 mg and 2,600 mg a day [1] |
| WHO (2026 fact sheet) | Adults | At least 3,510 mg a day "may be beneficial" [5] |
| Daily Value on US labels | Label reference | 4,700 mg [6] |
The Daily Value is a label reference, not a requirement. Children's and pregnancy values are on Potassium intake levels, blood pressure and the DASH diet. The sources we read did not give an upper intake level for potassium from food.
Low potassium
Low blood potassium (hypokalemia) is usually linked to a cause such as diuretics, diarrhea or vomiting, laxative overuse, eating disorders, chronic kidney disease or low magnesium. [7] It can cause weakness, spasms, palpitations and, with a large drop, abnormal heart rhythms. [7] Do not diagnose it from symptoms. A blood test is needed. [7] See Hypokalemia: low potassium causes, symptoms and treatment.Evidence by use
| Question | What the source found | Label |
|---|---|---|
| Higher intake and blood pressure | A review of 22 randomized trials (1,606 adults) found increased potassium intake lowered systolic pressure by 3.49 mm Hg, in people with hypertension but not those without. [8] | Evidence in adults with high blood pressure |
| Higher intake and stroke | Higher intake was associated with a 24% lower stroke risk (moderate-quality evidence). [8] | Observational association |
| Potassium-enriched salt substitute | In 20,995 people in rural China with prior stroke or aged 60+ with high blood pressure, a 75% sodium chloride / 25% potassium chloride substitute lowered stroke rate versus regular salt. [9] | Evidence in that group only |
| Potassium supplement pills for general health | Proper evidence not found. We checked the NHS, MedlinePlus, NIDDK and PubMed sources listed below. | None for healthy people |
The review authors wrote that the benefit applies to people without impaired kidney handling of potassium. [8] In the China trial, serious events attributed to hyperkalemia were not significantly higher with the substitute, but results do not transfer to other groups. [9]
Salt substitutes and supplements
WHO says lower-sodium salt substitutes can help people not at risk of hyperkalemia. [5] People with kidney disease are told to use herbs and spices instead of salt substitutes, which can be high in potassium, and to limit foods listing potassium chloride. [10] See Salt substitutes and potassium chloride.The NHS says 3,700 mg or less of potassium from supplements a day is unlikely to have obvious harmful effects, and that taking too much can cause stomach pain, nausea and diarrhea. [3] That is a UK statement for adults, not an instruction. Older people may be more at risk because their kidneys remove less, and the NHS says they should not take potassium supplements unless a doctor advises it. [3] The sources we read did not state how much potassium typical over-the-counter products contain.
Medicines
- ACE inhibitors, angiotensin receptor blockers, and potassium-sparing diuretics such as spironolactone, triamterene and amiloride can raise potassium. [1]
- The NHS says spironolactone can raise potassium, and bananas, avocados or salt substitutes can raise it further, so ask a doctor or dietitian. [11]
- The NHS lists potassium supplements and potassium salt substitutes among things that may not mix well with losartan. [12]
- Do not stop or start a medicine on your own. [2]
Labels and quality
Potassium is on the Nutrition Facts label, and 20% of the Daily Value or more per serving counts as high. [6] For product quality, see Quality testing and certifications. Liver disease and potassium was not covered in the sources we read.Frequently asked questions
Should I take a potassium supplement?
Only a clinician can decide that after a blood test. MedlinePlus says people treated for low potassium may need supplements, and the NHS says most people can get enough from food. [1][3]
Are salt substitutes safe?
They raise potassium intake on purpose. They suit some people and are risky with kidney disease or certain medicines. [5][10]
Do bananas have the most potassium?
No source we read ranks bananas first. Beans, lentils, potatoes, citrus, milk, yogurt, nuts and fish also contribute. [1]
What are signs of too much potassium?
There are often no symptoms. When present they can include chest pain, palpitations, weakness or a slow, irregular pulse. [2]
How much potassium do adults need?
It depends on the country and body: 3,500 mg a day for UK and EU adults, and 3,400 mg for men and 2,600 mg for women in the US figures MedlinePlus lists. [3][4][1]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Safety first: when extra potassium is risky
If you have kidney disease or another long-term illness, talk to your provider before taking potassium supplements. [1] If you are taking a potassium supplement and have vomiting, palpitations, weakness or trouble breathing, contact your provider right away. [2] Chest pain, sudden collapse or a slow, weak pulse can be signs of an emergency, so call emergency services (911 in the US). [2]
Details are on Hyperkalemia: high potassium, medicines that raise it and kidney disease. Medicine questions go to a pharmacist; see also Medication interactions.
Pregnancy, children and testing
References
- MedlinePlus (US National Library of Medicine). Review date 30 April 2026. Potassium in diet. Read 2026-10-23.
- MedlinePlus (US National Library of Medicine). Review date 1 October 2025. High potassium level. Read 2026-10-23.
- NHS (UK). Page last reviewed 3 August 2020. NHS, Vitamins and minerals: Others (phosphorus, potassium, salt). Read 2026-10-23.
- European Food Safety Authority (EU). News item 25 October 2016. Dietary reference values: advice on potassium. Read 2026-10-23.
- World Health Organization. Fact sheet dated 26 January 2026. Healthy diet. Read 2026-10-23.
- US Food and Drug Administration. Content current as of 5 March 2024. Daily Value on the Nutrition and Supplement Facts Labels. Read 2026-10-23.
- MedlinePlus (US National Library of Medicine). Review date 19 May 2025. Low blood potassium. Read 2026-10-23.
- Aburto NJ et al. BMJ 2013. Effect of increased potassium intake on cardiovascular risk factors and disease: systematic review and meta-analyses. PubMed abstract read 2026-10-23.
- Neal B et al. N Engl J Med 2021 (SSaSS). Effect of Salt Substitution on Cardiovascular Events and Death. PubMed abstract read 2026-10-23.
- National Institute of Diabetes and Digestive and Kidney Diseases (US). Last reviewed January 2025. Eating and nutrition for chronic kidney disease. Read 2026-10-23.
- NHS (UK). Page last reviewed 6 May 2026. NHS, Spironolactone. Read 2026-10-23.
- NHS (UK). Page last reviewed 10 June 2026. NHS, Losartan. Read 2026-10-23.