is a very significant body mineral, important to both cellular and electrical function. It is one of the main blood minerals called "electrolytes" (the others are sodium and chloride), which means it carries a tiny electrical charge (potential). Potassium is the primary positive ion (cation) found within the cells, where 98 percent of the 120 grams of potassium in the body is found. The blood serum contains about 4-5 mg. (per 100 ml.) of the total potassium; the red blood cells contain 420 mg., which is why a red-blood-cell level is a better indication of an individual's potassium status than the commonly used serum level.
Magnesium helps maintain the potassium in the cells, but the sodium and potassium balance is as finely tuned as those of calcium and phosphorus or calcium and magnesium. Research has found that a high-sodium diet with low potassium intake influences vascular volume and tends to elevate the blood pressure. Then doctors may prescribe diuretics that can cause even more potassium loss, aggravating the underlying problems. The appropriate course is to shift to natural, potassium foods and away from high-salt foods, lose weight if needed, and follow an exercise program to improve cardiovascular tone and physical stamina. The natural diet high in fruits, vegetables, and whole grains is rich in potassium and low in sodium, helping to maintain normal blood pressure and sometimes lowering elevated blood pressure. The body contains more potassium than sodium, about nine ounces to four, but the American diet, with its reliance on fast foods, packaged convenience foods, chips, and salt has become high in sodium (salt). Because the body's biochemical functions are based on the components found in a natural diet, special mechanisms conserve sodium, while potassium is conserved somewhat less.
Potassium is well absorbed from the small intestine, with about 90 percent absorption, but is one of the most soluble minerals, so it is easily lost in cooking and processing foods. Most excess potassium is eliminated in the urine; some is eliminated in the sweat. When we perspire a great deal, we should replace our fluids with orange juice or vegetable juice containing potassium rather than just taking salt tablets.The kidneys are the chief regulators of our body potassium, keeping the blood levels steady even with wide variation in intake. The adrenal hormone aldosterone stimulates elimination of potassium by the kidneys. Alcohol, coffee (and caffeine drinks), sugar, and diuretic drugs, however, cause potassium losses and can contribute to lowering the blood potassium. This mineral is also lost with vomiting and diarrhea.
Sources: Potassium is found in a wide range of foods. Many fruits and vegetables are high in potassium and low in sodium and, as discussed, help prevent hypertension. Most of the potassium is lost when processing or canning foods, while less is lost from frozen fruits or vegetables.
Leafy green vegetables such as spinach, parsley, and lettuce, as well as broccoli, peas, lima beans, tomatoes, and potatoes, especially the skins, all have significant levels of potassium. Fruits that contain this mineral include oranges and other citrus fruits, bananas, apples, avocados, raisins, and apricots, particularly dried. Whole grains, wheat germ, seeds, and nuts are high-potassium foods. Fish such as flounder, salmon, sardines, and cod are rich in potassium, and many meat foods contain even more potassium than sodium, although they often have additional sodium added as salt.