Potassium

Potassium is one of the most abundant minerals in the human body. A  150-pound person has about 250 grams (nine ounces) of potassium in his or her body. Many cellular enzyme systems depend on potassium, and nerve excitation and muscular contraction are influenced by the mineral.

A deficiency in potassium can cause muscular weakness, increased nervous irritability, mental disorientation, and cardiac irregularities. If blood levels of potassium get low enough, ventricular fibrillation (in which the heart vibrates rather than pumps) can occur and cause sudden death.  Muscle weakness, deterioration, and periodic paralysis from potassium deficiency are quite common.

Excess sodium in the diet can cause high blood pressure. Less publicized, however, is the equally well-established ability of potassium to counteract the effect of sodium in raising blood pressure. In animal experiments, potassium added to the diets of rats fed excess sodium not only extended lifespan but reduced blood pressure raised by the sodium.

Potassium requirements can be raised by many factors besides sodium intake, including vomiting, gastric drainage, alcoholism, renal disease, and anorexia. Medications which can cause a potassium deficiency include purgatives, laxatives, ammonium chloride, corticosteroids, carbenicillin, aminosalicylic acid, amphotericin, diuretics, glucagon, insulin, penicillin, and silver nitrate. Licorice eaten in excess has produced severe drops in potassium levels in the blood. Acute stress, trauma, or surgery can also cause a sudden deficit in potassium, with resultant impairment of glucose tolerance.

Probably the most common factor affecting potassium requirements is exercise or work. Substantial portions of the body's potassium can be lost in sweat. In human experiments, volunteers lost more than half their total body potassium after running eighteen to twenty miles in warm, humid weather. Diets with the recommended levels of potassium (2.6 grams) were adequate to replace potassium lost in the urine and feces, but not to replace that which was lost in sweat, and that amounted to more than what was lost through the other channels.

Potassium is removed from many processed foods. In fact, many of the same processing steps that remove potassium also add sodium. Food processors add salt to foods to "enhance" flavor. Many doctors believe salt is addictive, in the sense that we grow accustomed to the salty taste of foods and learn to "need" salt on just about everything.

One source of potassium that acknowledges our need for salt is the potassium salt substitute. Actually, there are cultures in the world that avoid sodium salt like the plague, and use only potassium salt. Several of these substitutes are available. Potassium is also available in supplementary form in a wide range of doses. Potassium salts are among the most heavily prescribed medications.

Where is it found ?

Natural food sources of potassium include bananas, lettuce, broccoli, potatoes, fresh fruit, peanuts (unsalted!), wheat germ, squash, nuts, and orange juice.

Who is likely to be deficient ?

So-called primitive diets provided much greater levels of potassium; modern diets may provide too little. Gross deficiencies, however, are rare except in cases of prolonged vomiting, diarrhea, or use of "potassium depleting" diuretic medications. People taking one of these medications should be informed by their doctor to take potassium. Prescription levels of potassium are higher than the amount sold over the counter but not more than the amount found in several pieces of fruit.

How much to take

The best way to get extra potassium is to eat several pieces of fruit per day. The amount allowed in supplements-99 mg per tablet or capsule-is very low, considering that one banana can contain 500 mg. Multiple potassium pills should not be taken in an attempt to get a higher amount, because they can irritate the stomach-a problem not encountered with the potassium in fruit.

Side effects

High potassium intake (several hundred milligrams at one time in tablet form) can produce stomach irritation. People using potassium-sparing medications should avoid the use of potassium chloride-containing products, such as Morton Salt Substitute, No Salt, Lite Salt, and others. Even eating several pieces of fruit per day can sometimes cause problems for people taking potassium-sparing diuretics, due to the high potassium content of fruit.

Potassium and sodium work together in the body to maintain muscle tone, blood pressure, water balance, and other functions. Many researchers believe that part of the blood pressure problem caused by too much salt (which contains sodium) is made worse by too little dietary potassium.

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