POTASSIUM

A very simple chemical substance present in the body in tiny amounts, potassium is nevertheless essential to certain important body functions.

Potassium is a metallic element which in the body exists in the form of positively charged ions (atoms which have acquired an electric charge). Together with another simple substance called sodium, potassium plays a vital role in the functioning of individual body cells.

WHAT POTASSIUM DOES ?

Potassium is essential to healthy nerve and muscle function. It is found chiefly within cells dissolved in cellular fluid, while sodium is principally outside cells.

The concentration of potassium inside, and sodium outside cells allows the transmission of impulses across each cell membrane. Thus messages are passed from one nerve cell to the next and muscle cells are enabled to respond to a given electrical signal.

Potassium is also vital for the maintenance of cell volume. Since it forms a high proportion of a cell's dissolved contents any loss of potassium will incur a loss of water making the cell shrink and function less efficiently.

THE BODY'S POTASSIUM BALANCE

Appreciable amounts of potassium are eliminated from the body each day in the urine, faeces, sweat and dead cells. The normal intake of food, especially meat, fruit and vegetables compensates for this, however, and any excess is excreted.

Sometimes illness can cause either an excess of potassium (hyperkalaemia) or a deficit (hypokalaemia), either of which can have serious consequences. The function of the heart muscle in particular may be impaired, creating disturbances in the heartbeat. Hyperkalaemia is often caused by diseases of the kidneys, and hypokalaemia by excessive water loss from the body. In both cases the balance is readily adjusted by suitable treatment.