Potassium is an essential macromineral in human nutrition with a wide range of biochemical and physiological roles. Among other things, it is important in the transmission of nerve impulses, the contraction of cardiac, skeletal and smooth muscle, the production of energy, the synthesis of nucleic acids, the maintenance of intracellular tonicity and the maintenance of normal blood pressure.

Diets high in potassium may be protective not only against hypertension but also strokes and cardiovascular disease and possibly other degenerative diseases, as well.

The major cause of potassium deficiency is excessive losses of potassium through the alimentary tract or through the kidneys. Potassium depletion typically occurs as a consequence of prolonged use of oral diuretics, from severe diarrhea and from primary or secondary hyperaldosteronism, diabetic ketoacidosis or in those on long-term total parenteral nutrition who have received inadequate potassium. Signs and symptoms of potassium deficiency include hypokalemia, metabolic alkalosis, anorexia, weakness, fatigue, listlessness and cardiac dysrhythmias. Prominent U-waves are seen in the electrocardiograms of those with hypokalemia.

Eating a variety of foods that contain potassium is the best way to get an adequate amount. Healthy individuals who eat a balanced diet rarely need supplements. Foods with high sources of potassium include orange juice, potatoes, bananas, avocados, parsnips and turnips, although many other fruits, vegetables, and meats contain potassium. Research has indicated that diets high in potassium can reduce the risk of hypertension.

A potassium level that is too high or too low can be dangerous. Abnormal potassium levels may cause symptoms such as muscle cramps or weakness, nausea, diarrhea, frequent urination, dehydration, low blood pressure, confusion, irritability, paralysis, and changes in heart rhythm.