Potassium: Functions, Food sources, Absorption and excretion

Potassium: Functions, Food sources, Absorption and excretion

Potassium is present in twice as much amount as sodium in the body. Approximately 250g of potassium is contained in the body and most of this is present in the cells i.e. in the intracellular fluid. When you read this article, you will find how closely the functions of sodium and potassium are interlinked.


  • Regulation of the balance of intracellular and extracellular fluid: Potassium along with sodium helps maintain fluid balance within the cell and outside the cell. Sodium is the main mineral present in extracellular fluid (the fluid outside the cell). Potassiun on the other hand, is the principal mineral in the intracellular fluid as indicated in figure. Together these two minerals help maintain fluid balance.

Minerals present in the body fluids

  • Regulation of the alkalinity/ acidity of body fluids: Potassium, like sodium, is alkaline. It combines with chloride which is acidic and together they help maintain the acidity/alkalinity of body fluids.

  • Role in muscle activity: Potassium has a significant role in the activity of skeletal and heart muscle. It helps in the transmission of messages which results in the contraction of muscle tissue.

Food sources

Potassium is widely distributed in foods. Meat, poultry and fish are good sources. Among the plant foods, pulses, fruits, vegetables especially the green leafy vegetables are good sources of potassium. The water of the tender coconut is however, the best source of potassium. Among the other fruits and vegetables, bananas, potatoes, carrots, tomatoes and lemons contain appreciable amounts of this mineral. Whole grain cereals also provide good amounts of potassium.

Absorption and excretion

What happens to potassium once it enters the body?

Potassium gets absorbed from the upper part of the intestine. The absorbed potassium then gets used up to perform the various body functions. Excess potassium is excreted in the urine and the faeces.

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