Potassium Overview

Potassium is a mineral found in many foods and supplements. But you will never see pure potassium in a healthfood store or pharmacy—it's a highly reactive metal that bursts into flames when exposed to water! The potassium you eat, or take as a supplement, is composed of potassium atoms bound to other nonmetallic substances—less exciting, perhaps, but chemically stable.

Potassium is one of the major electrolytesin your body, along with sodium and chloride. Potassium and sodium work together like a molecular seesaw: when the level of one goes up, the other goes down. All together, these three dissolved minerals play an intimate chemical role in every function of your body.

The most common use of potassium supplements is to make up for potassium depletion caused by diuretic drugs. These medications are often used to help regulate blood pressure, but by depleting the body of potassium, they may inadvertently make blood pressure harder to control.

Potassium is an essential mineral that we get from many common foods.

True potassium deficiencies are rare except in cases of prolonged vomiting or diarrhea, or with the use of diuretic drugs.

However, in one sense, potassium deficiency is common, at least when compared to the amount of sodium we receive in our diets. It is probably healthy to take in at least five times as much potassium as sodium (and perhaps 50 to 100 times as much). But the standard American diet contains twice as much sodium as potassium. Therefore, taking extra potassium may be a good idea in order to balance the sodium we consume to such excess.

Bananas, orange juice, potatoes, avocados, lima beans, cantaloupes, peaches, tomatoes, flounder, salmon, and cod all contain more than 300 mg of potassium per serving. Other good sources include chicken, meat, and various other fruits, vegetables, and fish.

Over-the-counter potassium supplements typically contain 99 mg of potassium per tablet. There is some evidence that, of the different forms of potassium supplements, potassium citrate may be most helpful for those with high blood pressure. ¹ Research indicates that it is important to get enough magnesium , too, when you are taking potassium. ² It might be wise to take extra vitamin B 12 as well. ³

When used by physicians, potassium is usually measured according to meqs (milliequivalents) rather than the more common mg (milligrams). A typical therapeutic dosage of potassium is between 10 and 20 meq, taken 3 to 4 times daily.

High Blood Pressure

According to a review of 33 double-blind studies, potassium supplements can produce a slight but definite drop in blood pressure. ⁴ However, two large studies found nobenefit. ⁵ The explanation is probably that potassium is only slightly helpful. When a treatment has only a small effect, it's not unusual for some studies to show no effect while others find a modest benefit. It's possible that potassium may only help people who are at least a bit deficient in this mineral.

Evidence suggests that potassium supplements may be most effective for people who eat too much salt. ⁶

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5. Whelton PK, Buring J, Borhani NO, et al. The effect of potassium supplementation in persons with a high-normal blood pressure. Results from phase I of the Trials of Hypertension Prevention (TOHP). Trials of Hypertension Prevention (TOPH) Collaborative Research Group. Ann Epidemiol. 1995;5:85-95.
6. Whelton PK, Buring J, Borhani NO, et al. The effect of potassium supplementation in persons with a high-normal blood pressure. Results from phase I of the Trials of Hypertension Prevention (TOHP). Trials of Hypertension Prevention (TOPH) Collaborative Research Group. Ann Epidemiol. 1995;5:85-95.