If you have high blood pressure, heart failure, or heart rhythm problems, getting enough potassium is especially important.

As well as as regulation of blood pressure, potassium is important in controlling the water content in cells, transmission of nerve impulses, digestion, muscle contraction, and heartbeat. It helps to maintain proper muscle and nerve function; it also helps in some important metabolic processes. Potassium regulates the water balance and acid-base balance in the blood and tissues. Blood serum potassium levels usually are determined to help evaluate heart rhythm irregularities, neuromuscular disorders and kidney function.
Potassium works with sodium to maintain the body's water balance.