Potassium is an essential mineral that is contained in every body cell.
Most of the Potassium in the body is found inside, rather than outside, the cells. Potassium has a small, positive electric charge and it helps to regulate the electrical activity in the cells, which is important for transmitting impulses between nerves and allowing muscles to contract. Potassium is also important for controlling the fluid levels in the body as well as the acidity (pH) of the body fluids. Potassium, together with sodium, helps to regulate the blood pressure and is important for the proper function of the heart and kidneys. Potassium is excreted mainly by the kidneys through urination and through the skin by perspiration. Potassium may play a role in reducing high blood pressure. Prolonged diarrhoea, vomiting, sweating and the use of some diuretics deplete the Potassium level. The Potassium in food is easily destroyed if food is soaked or boiled. If the levels of Potassium in the body are too high (Potassium toxicity), the heart cannot work normally and there is a risk of death from cardiac arrest (heart attack). Potassium is available in supplement form and is often found in combination with other minerals e.g. calcium, magnesium and potassium.
Symptoms of Potassium deficiency include nervous disorders, insomnia, hypertension (high blood pressure), constipation, a slow and irregular heartbeat and muscle damage. People with diabetes are often deficient in this mineral. Diuretics, fluid tablets and other heart disease medications tend to deplete the body of Potassium. Other symptoms of Potassium deficiency include muscle fatigue, poor appetite, mental apathy and general tiredness.
The best food sources of Potassium are prunes, raisins, tomatoes, bananas, vegetables, skim milk, beef and pork. Fresh fruit juices also contain large amounts of Potassium.
The recommended dietary intake (RDI) for Potassium is 1950 to 5460 mg (50 to 140 mmol) per day for adults. People with high blood pressure who are taking diuretic medications may be advised by their Doctor to eat Potassium-rich foods or take Potassium supplements. This is because diuretic drugs increase the amount of Potassium that is lost from the body.