Potassium is important in maintaining the fluid volume inside cells. During nerve transmission and muscle contraction, potassium and sodium briefly exchange places across cell membranes. This makes both sodium and potassium important in the response of muscles, including the heart muscle, to nerve messages.
Many Americans have a high sodium intake, but a low potassium intake. To prevent or delay the onset of high blood pressure and to lower elevated blood pressure, Dietary Guidelines recommend:
- decreasing sodium intake to 2,300 mg daily if you don’t have high blood pressure and to 1,500 mg daily if you have been diagnosed with high blood pressure
- increasing potassium from foods
- losing excess body weight
- increasing physical activity
- an overall healthful diet
Most Americans consume about 2,500 mg of potassium daily. The percent daily value for potassium provided on Nutrition Facts food labels is based on 3,500 mg of potassium daily (the RDA recommendation set in 1968). A higher intake than referenced on food labels is recommended by the Dietary Guidelines for Americans, released in 2005. That recommendation is that we meet a potassium intake of 4,700 mg daily.
Our potassium should come from foods, not supplements. Foods are so rich in potassium that supplements should not be necessary for healthy people eating a varied diet. Potassium toxicity from taking supplements is of greater concern than that people will develop a potassium deficiency.
Fruits and vegetables, that are rich in potassium, favorably affect acid-base metabolism, which may reduce the risk of kidney stones and bone loss. The banana is often cited as a good source of potassium, however, on a per calorie basis many vegetables provide more potassium than the banana. Including more vegetables in the diet not only increases potassium, but helps with weight loss or weight control. Low calorie vegetables provide bulky fiber that gives an “I’m full and satisfied” feeling.
Potassium rich fruits and vegetables include leafy green vegetables, fruits from vines, and root vegetables. Meat, milk, and cereal products contain potassium, but may not have the same effect on acid-base metabolism to reduce the risk of kidney stones and bone loss.
A medium banana has about 422 mg of potassium. Some foods providing more potassium than a banana are: