Potassium: Blood Pressure, Nerve Function and Heart Health

10 minutes

Potassium is an essential electrolyte for the heart, muscles, nerves and fluid balance. Learn how much you need, which foods provide it and why low blood potassium and potassium supplements require medical attention.

19 April 2025

Unagrande Yoga Expert

1179

What is potassium?
Why your body needs potassium
Daily potassium intake
Foods that contain potassium
How potassium relates to sodium and blood pressure
Who is at risk of low potassium?
Signs of potassium deficiency
Which test measures potassium levels?
When potassium medicines are needed
Who should avoid increasing potassium without medical advice?
The risks of too much potassium
Frequently asked questions
Key points about potassium

When people think of potassium, a banana is often the first food that comes to mind. In fact, this mineral is found in almost every food group, and lentils or a baked potato can provide considerably more.

Your nerves, muscles and heart need potassium, but the idea that “more is better” can be particularly dangerous here. Low blood potassium is more often associated with fluid loss, illness or medicines than with missing a banana. A supplement taken “for the heart” can cause potassium to rise too high in people with kidney disease or those taking certain medicines. Let us work through the details.

At a glance: the Russian dietary reference value for adults is 3,500 mg of potassium a day. Most healthy people can obtain this amount from food. Do not take potassium medicines or use salt substitutes containing potassium chloride without appropriate medical advice.

What is potassium?

Potassium is a mineral and the main positively charged ion inside cells. The difference between its concentrations inside and outside a cell creates an electrical gradient that makes nerve impulses and muscle contractions possible.

Most potassium is inside cells, while its blood concentration is maintained within a narrow range. The kidneys play the main role: they remove excess potassium in urine and reduce losses when intake is lower.

Why your body needs potassium

Potassium is involved in several important processes:

helping transmit nerve impulses;
enabling skeletal muscles and the heart to contract;
maintaining the volume of fluid inside cells;
supporting kidney function;
working with sodium to regulate fluid and electrolyte balance and blood pressure.

A potassium-rich diet usually includes plenty of vegetables, fruit, pulses and other whole foods. This overall eating pattern, rather than a single potassium tablet, is associated with healthier blood pressure.

Daily potassium intake

The Russian dietary reference value for adults is:

Group	Potassium per day
Adults	3,500 mg

The WHO recommendation is similar: at least 3,510 mg a day from food for adults. Current US adequate intake values are 3,400 mg for adult men and 2,600 mg for adult women; older sources may quote 4,700 mg. The 3,500 mg figure used here refers to the Russian standard, rather than a universal requirement for everyone.

These amounts apply to healthy adults. With chronic kidney disease, impaired potassium excretion or certain medicines, a safe intake may be different. Sometimes potassium needs to be restricted instead.

Foods that contain potassium

Potassium is found in more than fruit. Pulses, potatoes, dried fruit, vegetables, dairy products, fish and meat can all provide substantial amounts. It is easier to meet your needs by eating a variety of foods throughout the day.

Approximate amounts in typical portions:

Food and portion	Potassium
Dried apricots, ½ cup	about 755 mg
Lentils, cooked, 1 cup	about 731 mg
Baked potato, 1 medium	about 610 mg
Canned kidney beans, 1 cup	about 607 mg
Orange juice, 240 ml	about 496 mg
Soybeans, cooked, ½ cup	about 443 mg
Banana, 1 medium	about 422 mg
Milk, 240 ml	about 366 mg
Raw spinach, 2 cups	about 334 mg
Yoghurt, 170 g	about 330 mg
Salmon, cooked, 85 g	about 326 mg
Tomato, 1 medium	about 292 mg
Broccoli, cooked, ½ cup	about 229 mg

These figures are approximate: they depend on the variety, portion size and preparation method. Dried fruit is rich in potassium but also contains concentrated sugars, so it does not need to be your main source.

Can you get all the potassium you need from food?

Yes. For example, a cup of lentils, a baked potato, yoghurt, a banana, a portion of salmon, broccoli, a tomato, a glass of milk and a small portion of nuts over the course of a day provide roughly 3,500 mg of potassium together.

This is an illustration, not a prescribed menu: there are many suitable combinations. Vegetables, pulses, potatoes and fruit form the basis, with dairy products, fish or meat if you choose. A varied diet usually means a supplement is unnecessary.

How potassium relates to sodium and blood pressure

Sodium and potassium work closely together. Excess sodium encourages fluid retention and raises blood pressure in susceptible people, while adequate potassium helps the kidneys excrete sodium and supports normal blood vessel function.

Potassium is not a stand-alone treatment for high blood pressure. The whole diet matters: less excess salt and fewer ultra-processed foods, and more vegetables, fruit, pulses and whole foods. Do not stop prescribed medicines or replace them with bananas and supplements.

Who is at greater risk of low potassium?

Low dietary intake alone rarely causes significant hypokalaemia in a healthy person. Risk is higher in someone who:

has prolonged diarrhoea or repeated vomiting;
takes loop or thiazide diuretics;
misuses laxatives;
has inflammatory bowel disease or another condition that impairs absorption;
has undergone prolonged starvation and restarts intensive feeding without medical supervision;
loses large amounts of fluid and electrolytes during prolonged strenuous activity;
has magnesium deficiency, which can make hypokalaemia harder to correct.

Do not stop diuretics or other medicines yourself. If a medicine affects potassium, your doctor will decide whether blood tests and treatment adjustments are necessary.

Signs of potassium deficiency

Low dietary potassium often produces no noticeable symptoms. Cramps, tiredness, weakness and tingling are nonspecific: they occur in many conditions and cannot establish a diagnosis.

Hypokalaemia is a low blood potassium level confirmed by a laboratory test. Moderate or severe reductions may cause:

muscle weakness and spasms;
constipation;
palpitations;
abnormal heart rhythms;
profound weakness or paralysis in severe cases.

Severe weakness, fainting, chest pain or an irregular heartbeat requires urgent medical assessment rather than self-treatment with potassium.

Which test measures potassium levels?

Potassium is measured in blood serum or plasma. The reference range varies between laboratories but is often approximately 3.6–5.0 mmol/L.

The test shows the current concentration of potassium in the blood, but does not directly assess diet quality: almost all potassium is inside cells, and blood levels are tightly regulated. A normal result therefore does not mean someone is obtaining 3,500 mg from food every day.

A doctor may request the test for weakness or abnormal heart rhythms, kidney disease, fluid loss, or when someone takes diuretics, ACE inhibitors, angiotensin receptor blockers or other medicines that affect potassium. Sometimes a result is falsely elevated because blood cells break down during sampling; the laboratory or doctor may then recommend repeating the test.

Hair analysis or a “mineral screening” of fingernails cannot replace a blood test and medical assessment.

When potassium medicines are needed

Potassium medicines are used for confirmed hypokalaemia or specific medical conditions, in a dose and formulation chosen by a doctor. They are not a universal way to prevent tiredness, cramps or heart disease.

Potassium chloride, citrate or gluconate

Potassium chloride is often used to treat hypokalaemia, especially when associated with chloride loss or diuretic use.
Potassium citrate is prescribed for certain types of kidney stones and changes in urine composition. This is treatment for a specific indication, rather than an everyday supplement “for the kidneys”.
Potassium gluconate and other salts may be included in supplements, but what matters is the amount of elemental potassium, the diagnosis and safety, rather than the advertised formulation.

Do not attempt to convert a treatment dose between milligrams, millimoles and milliequivalents yourself. A potassium dosing error can be dangerous for the heart.

Panangin and Asparkam

These medicines contain potassium and magnesium as aspartates. They are not universal “heart vitamins” and are not needed by everyone with cramps or tiredness. The decision depends on test results, medical conditions, kidney function and other medicines.

How to take them

The regimen depends on the medicine and why it was prescribed. Some formulations are taken with food and sufficient water, and extended-release tablets must not be chewed or crushed. Follow the instructions for the particular product and your doctor's prescription.

Who should avoid increasing potassium without medical advice?

People whose potassium may be poorly excreted or raised by medicines need particular caution:

those with chronic kidney disease;
those who already have high blood potassium;
those with heart failure or adrenal insufficiency;
those taking ACE inhibitors or angiotensin receptor blockers;
those taking potassium-sparing diuretics, such as spironolactone;
those taking several medicines that affect kidney function and potassium levels.

In these situations, tablets are not the only concern: electrolyte powders, sports supplements and salt substitutes based on potassium chloride can also be dangerous.

Is potassium salt safe?

For some healthy adults, partially replacing sodium with potassium can be beneficial. However, a teaspoon of such a product may contain anything from several hundred to several thousand milligrams of potassium. If you have kidney disease or take the medicines listed above, do not use a salt substitute without discussing it with your doctor.

The risks of too much potassium

In a healthy person with normally functioning kidneys, potassium from food is generally safe: excess is excreted in urine. A universal upper intake limit has therefore not been established for potassium.

High doses of medicines, salt substitutes, kidney disease or medicines that reduce potassium excretion are a different situation. They can cause hyperkalaemia.

It often causes no noticeable symptoms. A marked increase may lead to:

muscle weakness;
tingling or numbness;
palpitations or an irregular heartbeat;
shortness of breath or chest pain;
dangerous abnormal heart rhythms;
paralysis in severe cases.

Chest pain, severe breathlessness, sudden weakness or an abnormal heart rhythm requires urgent medical help.

Frequently asked questions

Is a banana the best source of potassium?

No. A medium banana contains about 422 mg, compared with approximately 731 mg in a cup of cooked lentils and 610 mg in a baked potato. A banana is convenient, but does not have to be your main source.

Should you take potassium for cramps?

Not automatically. Cramps can relate to exercise, dehydration, the nervous system, medicines and other factors. Taking potassium without testing is particularly risky with kidney disease or certain cardiovascular medicines.

Does potassium help lower blood pressure?

A diet with adequate potassium and without excess sodium can support healthy blood pressure. But potassium does not replace a diagnosis of hypertension or prescribed treatment. Increasing vegetables, pulses and fruit is safer than taking treatment doses yourself.

Do you need potassium after exercise?

After an ordinary workout, water and regular food are enough for most people. Electrolyte solutions may be needed during very prolonged exercise, heavy sweating, hot weather or significant fluid loss, but their composition should suit the situation.

Can you take potassium and magnesium together?

A doctor may sometimes correct both electrolytes because magnesium deficiency can make potassium harder to restore. You do not need to add magnesium automatically, however. Read more in “Magnesium: Supporting Energy, Calm and Health”.

Should you take potassium every day for your heart?

The heart muscle does need potassium every day, but food is the preferred source. Potassium medicines are taken daily only when there is a medical reason and a safe dose has been selected.

Can you eat potassium-rich foods with kidney disease?

There is no single answer. Restriction may not be necessary in the early stages, while impaired potassium excretion requires a diet tailored to test results. Do not cut out vegetables and fruit yourself; discuss this with a doctor or dietitian who works with kidney disease.

Key points about potassium

The Russian dietary reference value for adults is 3,500 mg of potassium a day.
This amount can usually be obtained from vegetables, pulses, potatoes, fruit, dairy and other foods.
A banana is a good source of potassium, but far from the richest.
Low dietary intake and hypokalaemia are not the same thing.
Cramps and tiredness do not allow you to diagnose a deficiency yourself.
Potassium levels are checked with a blood test, particularly with kidney disease, fluid loss or medicines that affect them.
Potassium medicines, Panangin, Asparkam and salt substitutes are not suitable for unsupervised preventive use.
With healthy kidneys, potassium from food is generally safe, while excess from medicines can cause dangerous abnormal heart rhythms.

Potassium does not need to be labelled a “magic mineral for the heart”. A varied diet with vegetables, pulses, potatoes and fruit is the best way to obtain it regularly. Tests and medicines are best reserved for situations where they are actually needed.