Potassium is an element (and an electrolyte) that's essential for the body's growth and maintenance. It's necessary to keep a normal water balance between the cells and body fluids. Potassium also plays an essential role in the response of nerves to stimulation and in the contraction of muscles. Cellular enzymes need potassium to work properly.

A potassium deficiency due to increased urinary loss often occurs when medication for certain heart diseases is used to prevent sodium and water retention. To overcome this loss, physicians often suggest eating more foods high in potassium. More potassium may be prescribed as a medicine.

Foods high in potassium include bananas, cantaloupe, grapefruit, oranges, tomato or prune juice, honeydew melons, prunes, molasses and potatoes. Some foods high in potassium are also high in calories. When weight control is important, eat more low-calorie foods. Foods such as fruits, vegetables and low-fat dairy products that are high in potassium and calcium, when incorporated in the DASH Diet Study, helped to significantly lower blood pressure.