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Potassium (symbol K)
A metallic element, essential to the human body to help the cells maintain a correct fluid balance; and amounting to 5 per cent of its the total mineral content.
Potassium was discovered, in 1807, by Humphry Davy by electrolysis of caustic potash (KOH), the first instance of a metal being isolated by an electric current.
Together with sodium, potassium regulates the sodium-potassium balance that affects water retention and stimulates kidney function. It also regulates nerves, heart beat and blood pressure.
Potassium deficiency is rare, but its symptoms are water retentions (oedema), hypertension, irregular heartbeat, nervousness, fatigue and arthritis.
Bananas, are the best natural source, but pineapples, potatoes and tomatoes are also good sources. In its hexacyanoferrate form, its used in food manufacture as an anti-caking agent; and as potassium nitrate as a preservative and to add red colour to processed meat. See Saltpetre.