Functions: Potassium is very important in the human body. Along with sodium, it regulates the water balance and the acid-base balance in the blood and tissues. Potassium enters the cell more readily than does sodium and instigates the brief sodium-potassium exchange across the cell membranes. In the nerve cells, this sodium-potassium flux generates the electrical potential that aids the conduction of nerve impulses. When potassium leaves the cell, it changes the membrane potential and allows the nerve impulse to progress. This electrical potential gradient, created by the "sodium-potassium pump," helps generate muscle contractions and regulates the heartbeat.

Potassium is very important in cellular biochemical reactions and energy metabolism; it participates in the synthesis of protein from amino acids in the cell. Potassium also functions in carbohydrate metabolism; it is active in glycogen and glucose metabolism, converting glucose to glycogen that can be stored in the liver for future energy. Potassium is important for normal growth and for building muscle.

Uses: In medicine, potassium is one of the most commonly prescribed minerals. It is also commonly measured in biochemical testing and is supplemented if it is low. Because potassium is crucial to cardiovascular and nerve functions and is lost in diuretic therapy for edema or hypertension, a prevalent American disease, it must be added as a dietary supplement frequently. As stated before, the average American diet has reversed the natural high potassium-low sodium intake, and a shift back to this more healthful balance will help reduce some types of elevated blood pressure. Supplementing potassium can be helpful in treating hypertension specifically caused by a hyperresponse to excess sodium.

Pharmacological preparations of potassium are commonly prescribed for many of these conditions. A 10 percent potassium chloride solution is often given, but its taste is unpleasant. More easily used formulas are tablets that are swallowed or effervescent tablets. K-Lor, Slow-K, K-Lyte, and Kaochlor are common preparations. Time-release formulas such as Micro-K are also available.

Potassium chloride has occasionally been helpful in treating infant colic, some cases of allergies, and headaches. During and after diarrhea, potassium replacement may be necessary, and many people feel better taking potassium during weight-loss programs. Fatigue or weakness, especially in the elderly, is often alleviated with supplemental potassium, along with magnesium. Additional potassium may also be required for dehydration states after fluid losses and may be used to prevent or reduce hangover symptoms after alcohol consumption.

Deficiency and Toxicity: Elevations or depletions of this important mineral can cause problems and, in the extreme, even death. Maintaining consistent levels of potassium in the blood and cells is vital to body function.

Even with high intakes of potassium, the kidneys will clear any excess, and blood levels will not be increased. For elevated potassium levels, called hyperkalemia, to occur, there must usually be other factors involved; decrease in renal function is the most likely cause. Major infection, gastrointestinal bleeding, and rapid protein breakdown also may cause elevated potassium levels. Cardiac function is affected by hyperkalemia; electrocardiogram changes can be seen in this condition.