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Potassium (K)

An adult contains around 150 grams of potassium with 98% inside the cells. Potassium works in synergy with sodium, which is primarily found outside the cells in the tissue fluids. The potassium-sodium distribution is essential for the so-called electrolyte balance of cells, and this is crucial for the cellular uptake of nutrients, for the ability of cells to get rid of waste products, and for the maintenance of essential fluid balances. The kidneys regulate the body's potassium levels and they must always be in balance with sodium. A major sodium source is table salt (sodium chloride). Excessive consumption of sodium may result in a potassium deficiency.

Functions and importance for

  • Maintenance of the electrolyte balance (fluid and salt balance)
  • Blood pressure
  • Enzymatic processes
  • Nervous system, including muscle and heart impulses
  • Muscle contraction
  • Heart rhythm and cardiac contractility
  • Intestinal peristalsis via nerve and muscle impulses
  • Blood sugar levels
  • Oxygen metabolism in the brain and other tissues
  • Counteraction of acid surplus by means of alkalizing processes

Deficiencies and poor utilisation may be caused by

  • Unbalanced diets with low intake of potassium sources such as fruit and vegetables
  • Too much salt (sodium chloride)
  • Too much coffee and alcohol
  • Too much sugar
  • Diarrhea and vomiting
  • Excessive sweating
  • Stress where the corticosteroid aldosterone retains sodium and excretes potassium
  • Diuretics
  • Laxatives
  • Certain types of antibiotics
  • Overactive thyroid gland

Deficiency symptoms

  • Fatigue and limpness
  • Headache
  • Fluid retention, swollen ankles
  • Elevated blood pressure and irregular heart rate
  • Heart rhythm disturbances
  • Muscle cramps and hard muscles
  • Constipation
  • Pain in the joints and bones
  • Tingling sensation (needles and pins) in arms and legs
  • Dilated pupils
  • Cardiac arrest in serious cases

Please note: Potassium and magnesium deficiencies often result in the same symptoms.


Mainly seaweed, beans, dark leafy greens like spinach, dried apricots, Jerusalem artichoke, potatoes, avocados, oats, bananas, apples, mushrooms, almonds, nuts, and rosehips. Other sources are fish (especially salmon) and meat. Vegetarian sources are generally the best. Potassium and other minerals is also found in sea salt, which helps to improve the potassium-sodium balance.

Potassium content in mg per 100 grams

Seaweed 7,500
White beans 1,530
Almonds 725
Potatoes 414
Ret beet, salmon 330

Recommended daily allowance (RDA)

Adults: 11 years of age and older: 2,000-3,000 mg
Children: 1-10 years of age: 500-700 mg

Increased need

  • The larger the consumption of salt, the larger the need for potassium
  • Too much sugar, coffee, alcohol, and other stimulants
  • Excessive sweating
  • The above listed deficiency symptoms
  • Diuretics and the other listed medical drugs
  • Acid retention

Important information

We used to get a lot more potassium from the diet in earlier times. Today, it is the other way around and this imbalance may be potentially harmful. According to the Nordic Nutrient Recommendations women are advised not to ingest more than six grams of salt daily, while men are advised to stay below 7 grams. This is the equivalent of 2.4 and 2.8 grams of sodium respectively.
Minor potassium deficiencies may be controlled by means of diet - especially by consuming more potassium sources and less salt. Potassium supplements should be taken by people who use strong diuretics in order to avoid side effects of getting too little potassium. Because potassium loss varies from one person to another, blood levels of potassium should ideally be measured before and after treatment.

Overdosing - side effects

Rarely seen, but they may be caused by kidney diseases.

  • Weakness and reduced muscle strength
  • Impaired reflexes
  • Heart rhythm disturbances
  • Breathing difficulty
  • Numbness in arms and leg