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Potassium — The Complete Supplement Guide

The blood-pressure mineral most of us under-eat: what potassium does, why supplements are strictly dose-limited, deficiency, recommended intake and the real safety limits.

Reviewed by Bodil Isaksson, Licensed Biomedical Scientist (Sweden)Last reviewed July 2026Supplement guide

SupplementsMineralsPotassium

Most people eat too little of it, and it’s one of the highest-value minerals for blood pressure — yet, uniquely, supplements are tightly restricted for safety. For the short dietary version, see the Minerals page.

Read first — important. Potassium is the one mineral where supplements can be genuinely dangerous. High blood potassium (hyperkalaemia) can stop the heart. Do not take potassium supplements (or potassium-based salt substitutes) if you have kidney disease or take ACE inhibitors, ARBs or potassium-sparing diuretics without medical supervision. Get potassium from food unless a doctor prescribes otherwise.

Key takeaways

  • Most people eat too little; one of the best minerals for blood pressure.
  • Adults need ≈ 3,500 mg/day — from fruit, veg, legumes and dairy.
  • Food is safe; supplements are legally capped and high doses need medical supervision.

Function

Potassium is the principal positive ion inside every cell and the great counterweight to sodium. That partnership underpins electrical, fluid and metabolic balance throughout the body:

  • Resting membrane potential: the potassium gradient — maintained by the sodium–potassium pump — sets the electrical charge across cell membranes that lets nerves fire and muscles contract at all.
  • Nerve & muscle function: normal signalling and contraction, including a steady, coordinated heartbeat.
  • Fluid & electrolyte balance: the main intracellular cation, balancing sodium and controlling each cell's volume.
  • Blood pressure: relaxes blood-vessel walls and helps the kidneys excrete sodium — making it one of the most blood-pressure-lowering nutrients.
  • Heart electrical stability: both low and high potassium disturb heart rhythm, so the body guards its level closely.
  • Acid–base balance: helps buffer the body's pH.
  • Bone & kidney: adequate potassium (from fruit and vegetables) reduces urinary calcium loss, helping protect bone and lower kidney-stone risk.
  • Carbohydrate metabolism: needed to store glycogen and for normal insulin secretion.

Different forms — and which to choose

Unlike other minerals, over-the-counter potassium is legally dose-capped (e.g. ~99 mg per tablet in the US) because concentrated potassium can injure the gut and heart. Food is the main route.

From foodBy far the safest and recommended source — fruit, vegetables, legumes, dairy.
CitrateA medical form used to alkalinise urine and prevent kidney stones; prescription-strength.
ChlorideThe form used medically (oral or IV) to correct diagnosed deficiency — supervised only.
Salt substitutes"Low-sodium" salts replace sodium with potassium chloride — helpful for blood pressure but risky in kidney disease / on certain BP drugs.

Absorption in the body

How muchDietary potassium is well absorbed (~85–90%). The kidneys are the master regulator, matching excretion to intake — which is why healthy kidneys make food potassium very safe and why kidney disease makes it dangerous.
HelpsA whole-food diet rich in fruit and vegetables naturally provides plenty.
Hinders / riskImpaired kidney function and certain medicines (ACE inhibitors, ARBs, potassium-sparing diuretics) reduce excretion and can cause build-up.

Deficiency symptoms

Low potassium (hypokalaemia) usually comes from losses — vomiting, diarrhoea, or diuretics — rather than low diet, though chronic low intake keeps blood pressure higher than it needs to be.

SymptomsMuscle weakness and cramps, fatigue, constipation and — when more severe — abnormal heart rhythm.
Chronic low intakeContributes to high blood pressure and higher stroke risk, even without frank hypokalaemia.
Who's at riskPeople on diuretics, with ongoing vomiting/diarrhoea, eating disorders, or very low fruit/vegetable intake.

Recommended intake

Adults ≈ 3,500 mg/day

General adult reference intakes (an adequate-intake target, not an RDA):

  • Adults: ~3,500 mg/day (EFSA) · US AI 2,600 mg ♀ / 3,400 mg ♂
  • WHO suggests ≥3,510 mg/day to lower blood pressure and stroke risk.

Best food sources: potatoes and sweet potato, beans and lentils, bananas, dried fruit, avocado, tomato, spinach, yoghurt, fish. Most people fall well short.123

Therapeutic use

Strong evidenceLowering blood pressure — raising dietary potassium (or a potassium-based salt substitute) reduces blood pressure and stroke risk, part of the DASH approach.3
MedicalCorrecting diagnosed hypokalaemia; potassium citrate to prevent certain kidney stones — both under medical care.
Not for self-dosingGeneral "potassium supplements" for health are neither necessary nor safe at meaningful doses — the benefit comes from food.

Therapeutic doses

Food-first; medical doses supervised
EverydayAim for the ~3,500 mg/day target from fruit, vegetables and legumes — no supplement needed.
OTC supplementsCapped at small doses (~99 mg) — too little to matter for deficiency, and larger amounts should only be medical.
Medical repletionPrescription potassium (chloride/citrate) with blood-level monitoring — never self-administered at high dose.

Toxicity & upper limit

No UL from food (healthy) · supplements capped
Upper limitNo upper limit is set for potassium from food in healthy people — the kidneys handle it. No UL could be set for supplements either, which is why they are dose-restricted instead.1
HyperkalaemiaHigh blood potassium causes muscle weakness and dangerous heart-rhythm disturbances, and can be fatal. It arises mainly with kidney impairment or potassium-raising drugs.
InteractionsHigh risk with ACE inhibitors, ARBs, potassium-sparing diuretics and in kidney disease — including from salt substitutes. Combine potassium only under medical advice.

Bottom line: potassium is one of the best minerals for blood pressure and most people don’t get enough — but the fix is food, not pills: potatoes, beans, bananas, avocado, greens and yoghurt. Avoid potassium supplements and salt substitutes if you have kidney disease or take ACE inhibitors, ARBs or potassium-sparing diuretics unless your doctor says so.

← All supplementsShort dietary version

References

Reference and upper-limit values are general adult figures from official bodies; individual needs vary. Therapeutic doses describe clinical/research use, not prescriptions.

  1. US NIH Office of Dietary Supplements. Potassium — Health Professional Fact Sheet. ods.od.nih.gov
  2. EFSA Panel (NDA). Dietary Reference Values for potassium. EFSA Journal 2016;14(10):4592. efsa.onlinelibrary.wiley.com
  3. World Health Organization. Guideline: Potassium intake for adults and children (2012) — ≥3,510 mg/day to reduce blood pressure and stroke risk. who.int

This article summarizes nutrition science from official health authorities and peer-reviewed sources for education. It is not a substitute for individual medical advice, and the doses given are not prescriptions — always consult a professional before therapeutic supplement use, in pregnancy, in kidney disease, or alongside medication.

✓
Bodil Isaksson, Licensed Biomedical Scientist (Sweden)

At Food Health Lab we explain what the science says in plain language, and we cite our sources so you can check for yourself.

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