Ist Kalium gefährlich?

Is Potassium Dangerous?

Be careful when supplementing with potassium, as high levels of potassium can cause cardiac arrest.

Or simply: be careful with potassium, because potassium is dangerous.

Something I hear regularly in this or a similar form.

Especially when someone buys potassium in a pharmacy, such references are common.

What is referred to here is hyperkalemia, which is an increase in potassium levels in the blood serum. 

High concentrations of potassium in the blood are potentially life-threatening and manifest themselves in muscle weakness, paralysis, cardiac arrhythmia and even cardiac arrest.

One speaks of hyperkalemia when a potassium concentration in the blood serum of more than 5.0 mmol/L is measured. Hypokalemia is values ​​below 3.5 mmol/L. 

Mild hyperkalemia often remains asymptomatic. 

With a moderate to strong increase from 6-8 mmol/L, however, sometimes serious symptoms and, in the worst case, a fatal outcome are possible.

So is potassium dangerous?

It sounds like that at first glance. However, the real world looks different.

Especially if you consider the intake of potassium, which we have to distinguish in two forms

Oral intake of potassium – “Oral intake” means taking potassium by mouth. On the one hand from food and on the other hand from dietary supplements.

Parenteral administration of potassium - Parenteral administration is the introduction of a substance into the body bypassing the gastrointestinal tract, ie via an injection or infusion.

The distinction between these two forms of intake is crucial when it comes to increasing the concentration of potassium in the blood. 

The parental supply of potassium via injection or infusion enables a much faster and higher increase in the concentration of potassium in the blood than oral supply via food and dietary supplements, since the intestine acts as a barrier here, regulating the level and speed of absorption.

The EFSA - short for European Food Safety Authority - publishes the following data on the oral intake of potassium:

Potassium from dietary supplements

For the additional intake of potassium from dietary supplements, the highest dose of potassium was determined that has no recognizable and measurable negative effects even with prolonged intake. This value was set by EFSA at 1400 mg potassium per day.

The long-term intake of 3000 mg of potassium daily in the form of a dietary supplement in addition to conventional nutrition did not lead to any negative effects (2).

Undesirable effects of excessive potassium intake can appear in different ways. These are listed below, among others (2):

  • Potassium poisoning through intentional or unintentional ingestion of large amounts of potassium salts is possible. A single intake of potassium salts in amounts of up to 94 g led to symptoms of poisoning such as nausea, vomiting, abdominal pain and diarrhea.

For example, a dosage of 94g in a single dose would equate to an impressive 1566 capsules of a 60mg potassium supplement per capsule. 

It is also interesting that all the side effects listed by the EFSA – nausea, vomiting, abdominal pain and diarrhea – affect the intestines. This is an indication that when potassium is taken orally via dietary supplements, the intestine as a barrier plays a relevant role in controlling the concentration of potassium in the blood.

potassium from food

There are no known negative effects on healthy people from a high potassium intake from conventional food (1). The healthy kidney simply excretes excess potassium in the urine.

EFSA's upper limit of potassium intake for acute toxicity

The EFSA has set a value of 17.5 g per day as the upper limit for the acute toxicity of potassium (1). However, with known or unknown renal dysfunction, a daily intake of 5.9 g of potassium can lead to undesirable side effects such as an increase in the potassium concentration in the blood (2).

It is also crucial to note that these effects are not possible with an excessive intake of potassium from a conventional diet. Due to the dilution effect of potassium intake from conventional foods, high local concentrations and corresponding side effects are not to be expected (2).

So when is potassium dangerous?

The risk group for hyperkalemia is primarily older people with kidney disease, since the kidneys are crucial for potassium metabolism.

Before we take a closer look at potassium metabolism, here is some basic information about potassium.

What is potassium?

Potassium is a vital, essential mineral for humans. The bulk element is a positively charged ion and the seventh most common element in the earth's crust (2).

And what exactly is the effect of potassium?

The European Food Safety Authority – EFSA for short – has considered a number of the effects of potassium on humans to be certain.

These tested and scientifically proven effects are referred to as health claims and are as follows:

potassium contributes to the maintenance of normal blood pressure, normal functioning of the nervous system and normal muscle function.

How is potassium absorbed?

Potassium is absorbed rapidly and with high efficiency (≥ 90%), mostly in the upper parts of the small intestine (3). The absorption of potassium in the intestine is largely independent of the amount ingested and averages between 70 and 130 millimoles per day (2,3).

Where does the body store potassium?

The total amount of potassium in the human body is around 40-50 millimoles per kg of body weight and depends primarily on physique, age and gender (4). 

On average, men have a total potassium content of about 140 g. In women, total body potassium averages about 105 g (2,3).

In contrast to sodium, potassium occurs predominantly intracellularly, i.e. inside the cell. 

Potassium is quantitatively the most important cation in the cell interior. About 98% of the total potassium in the human body is found inside the cell (2,3).

In particular, hormones such as insulin, aldosterone and catecholamines, the acid-base balance and magnesium influence the distribution of potassium between the cell interior and exterior (2).

The potassium content of the cells varies depending on the tissue and reflects their metabolic activity. 

Muscle contains the highest proportion of the mineral (60%), followed by red blood cells (8%), liver cells (6%) and other tissue cells (4%) (2).

How is potassium excreted?

Excess amounts of potassium in the body are largely excreted through the kidneys. If the potassium balance is balanced, 85-90% is excreted in the urine, 7-12% in the stool and around 3% in the sweat (3).

Why are the kidneys so important for potassium?

Body potassium is primarily regulated by the kidneys. About 90% of the filtered potassium ions are absorbed in the renal tubules. Furthermore, potassium excretion is regulated in the renal tubules and in the collecting duct of the kidneys (2,3).

When the potassium balance is balanced, about 90% of the potassium ingested is eliminated via the kidneys within 8 hours and more than 98% within a day (2,3).

This means a healthy kidney regulates the potassium level in the blood very effectively.

And in the case of a kidney function disorder?

The regulation of potassium homeostasis via the kidneys is very precise, provided the kidney function is normal. 55% of patients with chronic kidney failure have an elevated serum potassium level (hyperkalemia) (5).

Hyperkalemia is almost always found in patients with acute renal failure, especially when the subject is exposed to extensive catabolic processes. These include operations, stress or cortisone therapy. Tissue breakdown, such as that associated with hemolysis, infection, or burns, can also lead to hyperkalemia.

Such patients with disorders of potassium homeostasis should be subject to constant monitoring of potassium serum levels and potassium intake (3).

This also closes the circle as to why the risk group for hyperkalemia is primarily older people with kidney disease.

In addition to too much, there is of course also too little potassium. Which is much more common based on the available data.

How common is a potassium deficiency?

In the National Consumption Study II (NVS II, 2008), the nutritional behavior of the population in Germany was examined and shown how this affects the average daily nutrient intake with macro and micronutrients.

The intake recommendations of the German Society for Nutrition (DGE) are used as a basis for assessing the nutrient supply. A comparison between the recommended intake and the actual nutrient intake provides information about which micronutrients are more frequently undersupplied in Germany.

What is the supply situation of potassium in Germany?

  • Overall, 56% of men and 77% of women aged 35 to 50 fall short of the recommended daily intake of potassium.
  • The poorest men (aged 35 to 50) lack 1806 mg of potassium. This corresponds to a daily deficit of 45% of the recommended intake.
  • The poorest women (aged 35 to 50) lack 2130 mg of potassium. This corresponds to a daily deficit of 53% of the recommended intake.
  • Pregnant women do not need more potassium than their non-pregnant peers. They are therefore subject to the same shortfall situation. Accordingly, the poorly supplied pregnant women lack 2130 mg of potassium per day.
  • Breastfeeding women have a 400 mg higher potassium requirement than their non-breastfeeding peers, namely 4,400 mg of potassium per day. The poorest breastfeeding mothers (aged 25 to 34) are missing 2,597 mg of potassium. This corresponds to a daily deficit of 59% of the recommended intake.

Does this intake recommendation apply to everyone?

Of course, there may be additional individual needs. The DGE also clearly admits this, since the intake recommendations of the DGE are based on the needs of healthy and normal-weight people with normal everyday stress. 

The calculated additional requirement for potassium can also be higher. The individual requirement can be above the intake recommendations of the DGE due to diet, alcohol consumption, stress and sport, for example.

What exactly is the recommended daily allowance of potassium?

In the European Union, the recommended daily dose of potassium has been set at 2000 mg. This is the amount that an average person should consume daily to meet their potassium needs.

The individual requirement can, for example, be above the intake recommendations of the DGE due to diet, consumption of stimulants, stress and sport.

Here are the DGE intake recommendations for different age groups for potassium.

Infants 0 to 4 months – 400 mg/day

Infants 4 to 12 months – 600 mg/day

Children 1 to 4 years – 1100 mg / day

Children 4 to 7 years – 1300 mg / day

Children 7 to 10 years – 2000 mg / day

Children 10 to 13 years – 2900 mg / day

Children 13 to 15 years – 3600 mg / day

Adolescents and adults 15 to 65+ years – 4000 mg/day

Pregnant women – 4000 mg/day

Breastfeeding – 4400 mg/day

Perhaps the most interesting point here is that while the general recommendation is 2000mg of potassium per day, the specific recommendation for people over the age of 15, who make up the vast majority of the population, is exactly double that, at 4000mg. 

And here, too, there may be an individual additional requirement based on various factors.

How much potassium is in food?

When thinking of dietary potassium, the first thing that springs to mind for most people is the banana. However, that's more good marketing from the banana industry than a really relevant association based on the numbers. 

Here is a brief overview of some foods that are higher in potassium:

Beef – 340mg of potassium per 100g of food

Veal Fillet – 348mg of potassium per 100g of food

Salmon – 371mg of potassium per 100g of food

Broccoli – 373mg of potassium per 100g of food

Bananas – 382mg of potassium per 100g of food

Mackerel – 396mg of potassium per 100g of food

Potato – 411mg of potassium per 100g of food

Trout – 413mg of potassium per 100g of food

Goose – 420mg of potassium per 100g of food

Milk Chocolate – 436mg of potassium per 100g of food

Wheatnuts – 544mg of potassium per 100g of food

Spinach – 633mg of potassium per 100g of food

Brazil Nuts – 644mg of potassium per 100g of food

Lentils – 810mg of potassium per 100g of food

Peas – 935mg of potassium per 100g of food

Cocoa Powder – 1500mg of potassium per 100g of food

Lima Beans – 1725mg of potassium per 100g of food

Is Potassium Dangerous?

In summary, the answer is, of course, yes. 

Potassium can be dangerous if the concentration in the blood is high. However, this is primarily relevant for older people with kidney diseases. Since the intestines and kidneys regulate the potassium level in the blood very effectively.

Food and dietary supplements therefore have no or a much smaller effect on this than a disturbed excretion of potassium as caused by kidney disease or even a parenteral supply of potassium.

In addition, based on the data from the EFSA and DGE, a potassium deficiency is statistically much more common than a potassium concentration that is too high.

Potassium is an essential, vital mineral that performs important tasks in the body. Therefore, it should be the goal of everyone to cover their needs optimally. 

For more performance in everyday life and training and of course for more well-being.


  1. Scientific Committee on Food (SCF) and Scientific Panel on Dietetic Products, Nutrition and Allergies (NDA) of EFSA, Tolerable Upper Intake Levels for Vitamins and Minerals, European Food Safety Authority 2006, ISBN: 92-9199-014-0
  2. Federal Institute for Risk Assessment: Domke A., Großklaus R., Niemann B., Przyrembel H., Richter K., Schmidt E., Weißenborn A., Wörner B., Ziegenhagen R. (eds.), Use of minerals in food - Toxicological and nutritional aspects Part 2.; BfR in-house print shop Dahlem, 2004
  3. Biesalski HK, Fürst P., Kasper H. et al. (2004) Nutritional Medicine. According to the curriculum for nutritional medicine of the German Medical Association. 3. Edition. Georg Thieme Verlag, Stuttgart
  4. He Q, Heo M, Heshka S et al (2003) Total body potassium differs by sex and race across adult age span. Am J Clin Nutr; 78:72-77
  5. Gennari FJ, Segal AS (2002) Hyperkalemia: An adaptive response in chronic renal insufficiency. Kidney Int; 62:1-9
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