Potassium is an important mineral whose importance is often overlooked. However, it plays a huge role in optimal functioning of both the heart and the nervous system. Potassium also plays a role in maintaining fluid and electrolyte balance in body cells. The average person should consume an estimated 2,000 milligrams of potassium per day. Excellent sources of potassium include: raisins, prunes, bananas, strawberries, watermelon, cantaloupe, oranges, beans, peas, turkey and fish.