To Your Health

Q. Can you tell me the benefits of taking potassium? Is there enough in my multivitamin/mineral? What foods are rich in potassium?

A. Potassium is the primary mineral residing inside the cells of our body. Sodium is kept mostly outside by the cell membrane, and the body uses the energy that this separation generates to do a great many of the tasks required to keep us alive.

Potassium is plentiful in the American diet, and an intake of 2,000 to 4,000 milligrams per day is not hard to accomplish. Potassium-rich foods include fresh fruits (such as avocados, bananas, apricots, cantaloupe, honeydew melon, and citrus fruits to name just a few), vegetables (especially when eaten raw or steamed without added salt), grain products, nuts, and meat. Until food processors (or we ourselves) salt our food, it provides more potassium than sodium.

Potassium deficiency is seldom due to low dietary intake, although potassium depletion from excessive use of alcohol, caffeine, salt, or sugar is possible. More often, problems with potassium are related to fluid loss from excessive vomiting or diarrhea or to serious illness such as kidney failure or diabetic acidosis. The symptoms associated with lack of potassium include fatigue, irregular heartbeat, swelling, constipation, edema, dizziness, mental confusion, and inordinate thirst.

It would be difficult to get too much potassium from dietary sources alone, but supplements can elevate body potassium levels high enough to provoke an imbalance with sodium that can result in kidney damage and other serious complications. Because of these risks, the Food and Drug Administration limits the amount of potassium in nonprescription products to 99 mg per day. Your multivitamin may list anywhere from 5 mg to 99 mg of potassium on the ingredient label, but a dietary supplement of anything less than 250 mg is really insignificant.

Potassium supplementation should be done only under medical supervision and based upon a medical need. There are several medical conditions that respond to potassium supplements:

Potassium supplements of 2,500 mg per day lower blood pressure in patients with mild hypertension.

Potassium supplements decrease urinary calcium excretion, and individuals with diets high in potassium have a lower risk of developing kidney stones.

Low blood potassium causes heart arrhythmias that can be life threatening, but elevated blood potassium can be fatal.

People with potassium intake less than 2,400 mg per day were 1.5 times more likely to have a stroke compared to those with intake more than 4,000 mg per day. Among people taking diuretics, those with the lowest potassium intake were 2.5 times more likely to have a stroke than those with the highest intake of potassium.

Stroke victims with the lowest blood potassium concentration immediately following a stroke recover their ability to function more slowly and have a higher mortality rate than the patients with higher potassium concentrations.

Maintaining a good level of potassium intake by emphasizing fresh, unprocessed food in your diet is certainly prudent. You should use potassium supplements only under a doctor's supervision, and he should monitor your blood level of potassium to be sure you don't take in too much.