Potassium is a mineral essential to maintain proper health. On the periodic table of the elements, potassium has the atomic number of 19 and atomic symbol of K. It was first isolated by Sir Humphry Davy in 1807. It is a soft metal that can easily be cut by a knife. Potassium is one of the most highly reactive metals and rarely used alone. Combined with many other elements, such as sodium or chloride, however, it forms compounds which can be found in many common items such as glass, soap, and fertilizer.

Potassium is probably best known as an important nutrient. It can be found in a variety of foods, from bananas, apples, broccoli, and peas, to whole grains, nuts, flounder, and salmon. Potassium, one of the main electrolytes, is an essential element in the basic, everyday workings of the body. It plays a role in muscle growth and contractions, nerve cell function, and protein synthesis. Along with another electrolyte, sodium, it also helps to to regulate the water balance in and outside of the cell.

A lack of potassium can cause fatigue or muscle cramps, but a severe potassium deficiency, or hypokalemia, can cause serious problems such irregular heart function, nervous system impairment, and even death. Hypokalemia is usually caused by gastrointestinal problems such as diarrhea or vomiting, or by the use of diuretics to treat other conditions. As potassium is regulated by the kidneys, a renal condition could also affect the amount of potassium in the body.

It is more unusual to have elevated levels of potassium, called hyperkalemia, as any excessive amounts will removed by the kidneys and excreted through urine. Usually hyperkalemia will be caused by a medical condition such as a major infection or renal impairment and could affect cardiac function as well. There is not a specific RDA for potassium, but a healthy individual who eats the recommended fruits and vegetables should get a sufficient amount.