Keeping your heart beating in time

What is potassium?

Potassium is one of the most important minerals in the human body and plays a decisive role in many biological processes. As a positively charged ion (cation), it is found primarily inside cells and is responsible for the electrical potential across cell membranes. This potential is essential for the transmission of signals between nerve and muscle cells.

Another important property of potassium is its role in the regulation of the acid–base balance. The body uses potassium to help stabilise pH by exchanging it with protons between the cell interior and exterior. Potassium also contributes to the maintenance of healthy blood pressure, which is why an adequate potassium intake is especially recommended for people with high blood pressure.

What functions does potassium have in the body?

Potassium plays a key role in the conduction of nerve impulses. The targeted exchange of potassium and sodium ions across cell membranes generates an electrical potential that activates nerve cells. This mechanism enables movements, reflexes and the function of the heart muscle. An imbalanced potassium level can affect the excitability of nerves and muscles and lead to muscle cramps or heart rhythm disorders.

About 60% of the human body consists of water, present both inside and outside cells. Potassium is the most important electrolyte inside cells and controls the amount of water in the cells. Sodium, on the other hand, regulates fluid balance outside the cells. Both work together with other electrolytes such as chloride to maintain osmotic pressure and fluid balance.

Adequate potassium intake helps regulate blood pressure. Potassium supports the excretion of excess sodium, which otherwise can lead to hypertension. Studies show that a potassium-rich diet can help lower blood pressure and reduce the risk of cardiovascular disease.

Through its blood-pressure-lowering effect, potassium also reduces the risk of stroke. Studies indicate that people with higher potassium intake have up to a 24% lower risk of stroke compared with those with lower intake.

Potassium can help maintain bone density by reducing calcium loss in the urine. Reduced calcium excretion protects the bones and can lower the risk of osteoporosis.

Potassium plays an important role in the regulation of body pH. Because potassium and protons (also positively charged particles) can be exchanged between the cell interior and exterior, it helps stabilise the acid–base balance and counteracts excessive acidosis.

It is also an important component of many enzymes required for protein synthesis and cellular metabolism. It supports the formation of proteins, which are important for cell growth, muscle development and many other bodily functions.

Potassium salts have traditionally been used to help remove excess fluid from the body. They promote sodium excretion, which in turn stimulates urine production and can reduce water retention.

When is the potassium level measured?

Measuring the potassium level in the blood is necessary when there is suspected potassium deficiency or excess. Because potassium plays a central role for nerves, muscles and the cardiovascular system, deviations can cause health problems. Typical signs of potassium deficiency are muscle cramps, fatigue or heart rhythm disturbances, while excess potassium can lead to muscle weakness, tingling and also cardiac problems.

Regular monitoring is also required when taking certain medications that affect potassium balance. These include diuretics, which increase potassium loss via the kidneys, and cardiac glycosides, used in heart failure. Medications for arrhythmias can also alter potassium concentration.

Potassium monitoring is particularly important in people with chronic conditions such as kidney disease or high blood pressure. Since the kidneys play a key role in potassium excretion, impaired kidney function can lead to excess potassium. At the same time, potassium influences blood pressure, so both people with high and low blood pressure should have their potassium levels checked regularly. Timely measurement can help detect health risks early and avoid serious complications.

Potassium level: what is normal?

The potassium level in the body is an important health indicator and is assessed according to established reference values in blood and urine. In adults, a potassium level between 3.5 and 5.1 mmol/l is considered normal. Deviations may indicate health problems. The daily requirement for potassium is at least 4 grams, which is generally easily met through a balanced diet.

A too-high potassium level – hyperkalaemia – starts at around 5.2 mmol/l. At values above 6.0 mmol/l there is an acute danger to the heart. In such cases prompt medical treatment is necessary to prevent serious complications.

Blood potassium concentration is not constant and varies with age. In newborns it can be between 3.2 and 5.5 mmol/l in the first days after birth, in children aged 1 to 16 years between 3.3 and 4.6 mmol/l. Despite these slight fluctuations, potassium levels remain relatively stable throughout life.

In addition to blood tests, a urine sample can also provide information about potassium balance. The normal potassium value in 24-hour collected urine is between 30 and 100 mmol/l. A markedly low value may indicate that the body is losing potassium via the kidneys or the gut, which should be further investigated in case of deficiency. In particular during fasting potassium in urine can drop to as low as 10 mmol/l.

Does the daily diet cover potassium needs?

Daily food usually provides enough potassium, so deficiency is rare. On average, people consume about 2 to 3 grams of potassium per day through food. With a balanced diet potassium requirements are generally easily covered.

However, there are situations in which the body needs more potassium. In particular, people with high blood pressure, heart disease or after a stroke should aim for 4 to 5 grams of potassium daily to support heart health. Stress, magnesium deficiency, high salt intake, excessive alcohol consumption or malnutrition can also increase potassium requirements. Severe vomiting, diarrhoea, trauma or laxative abuse also raise the need, since the body loses more electrolytes.

Older people in particular and individuals with kidney or liver disease should have their potassium balance checked regularly, as their bodies may not handle or excrete potassium optimally. In such cases a targeted dietary adjustment or medically supervised potassium supplementation may be necessary.

In which foods is potassium found?

Foods especially rich in potassium include legumes, nuts, mushrooms, whole-grain products, fruit and vegetables. Top sources are chanterelles (5370 mg/100 g), soybeans (1800 mg/100 g) and cocoa powder (1500 mg/100 g). Chickpeas, white beans and lentils also provide over 800 mg per 100 g and are excellent potassium sources. Nuts such as pistachios and almonds, as well as green vegetables like spinach and parsley, also contain high amounts. Bananas, potatoes and apricots are also known for their potassium content, though somewhat lower (approx. 400–600 mg per 100 g).

Potassium: how to integrate this important mineral into your diet

• Rely on dried fruits as potassium sources. Dried apricots, dates and peaches contain particularly high potassium because the mineral is concentrated during drying. 100 grams of dried apricots provide, for example, up to 1'162 milligrams of potassium – an ideal snack between meals.
• Supplement your diet with legumes and nuts. Lentils, chickpeas and beans are excellent potassium sources and also provide valuable plant proteins. Nuts like almonds and pistachios are rich in potassium and make great healthy snacks.
• Keep the skin on when preparing potatoes. Potassium is particularly concentrated in potatoes when the skin is left on. A medium-sized potato with skin can contain up to 900 milligrams of potassium. Bake or steam potatoes to preserve as many nutrients as possible.
• Avoid potassium losses when cooking. A considerable portion of potassium goes into the cooking water. To prevent this, steam your vegetables or reuse the cooking water, for example in soups or sauces.
• Potassium-rich foods often have a mildly diuretic effect. Therefore, drink enough water to balance fluid levels and keep the body well nourished.
• If you have kidney disease, pay special attention to your potassium intake, as excessive potassium can pose health risks. Have your potassium level checked regularly by a physician.
• Many dietary salts and low-sodium convenience foods contain large amounts of potassium chloride. If you need to limit potassium intake, avoid these products and use natural herbs and spices instead.
• Coffee and cola can negatively affect potassium balance, as they promote renal excretion of potassium. Instead, drink potassium-rich mineral water to support your mineral intake.
• If you need to regulate your potassium intake, combine potassium-rich foods with low-potassium options. For example, white bread with fresh cheese and tomato or chicken schnitzel with rice balance potassium content.
• Potassium and magnesium work together in the body to support muscle and nerve function. Therefore, ensure a balanced magnesium intake through foods such as nuts, whole grains and green vegetables.

Potassium is an important mineral that supports numerous bodily functions and is essential for overall well‑being. It contributes to the regulation of fluid balance, nerve and muscle function and blood pressure. A balanced diet with potassium-rich foods helps maintain physical health and prevent possible deficiencies.