Potassium in food: sources, preparation and common myths

Potassium supports normal cell function, nerve transmission, muscle contraction and heart function. The kidneys play a central role in removing excess potassium. [1]

In healthy people with normal kidney function, abnormally low or high blood potassium is uncommon. Prolonged vomiting or diarrhoea, kidney disease and some medicines can disturb this balance. [1]

Potassium is widely distributed across the diet: vegetables, pulses, fruit, potatoes, nuts, dairy foods, fish and meat can all contribute. Less processed foods often make it easier to vary sources. [1][2]

Exact values depend on variety, portion, storage and recipe, so a composition database is preferable to a universal ranking.

Potassium dissolves in water. Boiling in a large volume of water and draining can therefore move some potassium into the cooking water. The effect depends on the food, cutting, water volume and cooking time. [3]

For the general population, this does not mean every vegetable should be boiled or its cooking water always discarded. In chronic kidney disease, soaking, cutting and double-cooking may be used with a specific potassium-reduction goal and professional guidance. [3][4]

Processed foods may also contain potassium additives. Read the ingredient list as well as the nutrition panel.

WHO recommends increasing potassium from food in adults to reduce blood pressure and cardiovascular, stroke and coronary-heart-disease risk. It suggests at least 90 mmol, or 3510 mg, per day for adults; this conditional recommendation does not cover people with impaired potassium excretion because of disease or medication. [2]

This is a public-health reference, not an individual prescription. Read it alongside sodium guidance and personal medical advice.

“Bananas are the best source”

Bananas provide potassium, but so do vegetables, pulses, potatoes, fruit, dairy foods, fish and meat. The useful choice depends on the portion and overall diet. [1][2]

“Boiling destroys potassium”

Heat does not simply destroy it. Some potassium can move into the cooking water, especially after cutting; draining matters. [3]

“Potassium salt is a risk-free alternative”

No. Potassium salts can be dangerous with kidney disease or medicines that raise blood potassium. ANSES advises medical advice before using them in low-sodium diets. [5]

“More potassium is always better”

A population recommendation does not replace medical assessment. Excess risk is concentrated in people with reduced renal excretion or relevant medicines. [1][5]

Kidney disease, dialysis, prolonged vomiting or diarrhoea, and some medicines can alter potassium balance. ACE inhibitors, some angiotensin-receptor blockers and potassium-sparing diuretics are situations requiring medical vigilance. [1]

1. 01Vary vegetables, fruit, pulses and other food sources.
2. 02Consider the portion and the whole recipe.
3. 03Read ingredients for potassium additives.
4. 04Do not confuse dietary potassium with potassium salt.
5. 05Follow a prescribed plan rather than a general internet rule.