High-potassium foods: which foods contain it and how much you need

What is potassium for?

Potassium is involved in nerve transmission, muscle contraction and fluid balance [2]. The body keeps its concentration in the blood within a narrow range. That is why eating a food rich in potassium does not suddenly change what happens in the muscle.

An eating pattern that includes vegetables, fruit, pulses and other minimally processed foods makes it easier to get an adequate amount. Potassium is part of the relationship between diet and blood pressure examined by the European Food Safety Authority (EFSA) [2]. If blood pressure is your concern, our diet guide for hypertension explains the full approach.

Which foods contain the most potassium per serving?

The figures come from the Spanish Food Composition Database (BEDCA) and have been calculated for an indicative serving using the values per 100 g [1]. They are approximate because variety, size and cooking can change them.

Food	Indicative serving	Potassium per serving
Boiled chickpeas	150 g	about 503 mg [1]
Boiled spinach	150 g	about 688 mg [1]
Boiled potato	200 g	about 827 mg [1]
Banana, peeled	120 g	about 420 mg [1]
Almonds	30 g	about 251 mg [1]
Grilled salmon	150 g	about 540 mg [1]

Banana provides potassium, although a serving of potato or spinach from this table provides more [1]. You do not need to choose foods from the top row every time, either. A chickpea dish with vegetables adds several sources together.

How much potassium is needed each day?

For adults, the EFSA’s adequate daily intake is 3,500 mg a day, equivalent to around 90 mmol [2]. This is a population reference and a guide; there is no need to count every food. During lactation, the reference is 4,000 mg, around 102 mmol [2].

For children, the reference changes with age. It ranges from 800 mg a day, around 20 mmol, for ages 1 to 3, up to 3,500 mg, around 90 mmol, for ages 15 to 17 [2]. 1 mmol of potassium is about 39 mg.

EFSA has not set a maximum limit because there is not enough data [2]. If you have kidney disease or take medication that retains potassium, your doctor will determine your limit.

What is the relationship between potassium and cramps?

Potassium is involved in muscle contraction [2], but getting a cramp during exercise does not mean you are deficient in it. A review of nine studies found that having had cramps before was the factor most strongly linked to having them again [3]. Among people who had cramps, blood potassium levels after competition were even slightly higher [3].

If this happens when you train, increase your workload gradually and take heat and tiredness into account. There is no evidence that eating more bananas prevents the next cramp [3].

Staying hydrated remains part of looking after yourself during exercise, especially in hot weather. There is no universal amount that prevents cramps. If cramps are frequent, also occur at rest or have changed, discuss them with your doctor to assess other possible causes.

How does cooking affect potassium?

When vegetables, potatoes and pulses are boiled in water, some of the potassium passes into the cooking liquid [4]. Discarding the water reduces the amount left in the food. The extent varies with the way the food is cut, the food itself and the cooking time. That is why the figure for a boiled potato cannot be used to calculate precisely how much potassium is in a roast potato.

Soaking and double cooking have also been studied as ways to reduce potassium. The review found reductions with several techniques, especially those using water, although comparable procedures are lacking for all foods [4]. This is a cooking fact, not a universal kidney diet recommendation.

If you need to control potassium because of kidney disease, the cooking method should be decided in light of your test results, treatment and overall diet. Our chronic kidney disease diet guide explains how this approach is personalised.

If you have kidney disease or take medication for blood pressure

If you have kidney disease or take certain blood pressure medicines, the right amount may be different for you. Some of these medicines make the kidneys remove less potassium, while certain diuretics make them remove more. Your doctor will decide whether foods or medication need adjusting based on your test results [5][6].

Salt substitutes containing potassium chloride provide a lot of potassium in a small amount [6]. If you have kidney disease, are pregnant or take medicines that retain potassium, consult your doctor before using a potassium chloride salt substitute [5][6].

The chronic kidney disease diet guide explains how potassium can be managed without removing fruit and vegetables; also take potassium additives in processed foods into account [5].

What we see in consultations

“Do I need to eat a banana after training?” This is a common question in consultations. A banana can be a convenient fruit, but there is no evidence that it prevents cramps on its own [3]. If you are looking for a snack, choose according to your hunger, schedule and tolerance.

“Can I eat potatoes if I take blood pressure medication?” It depends on the medicine, kidney function and test results. The table cannot answer that. If your aim is to reduce salt, our no-added-salt menu plan offers meal ideas.