Potassium and sodium exist in important ratios, potassium concentrated inside the cell and sodium remaining outside. They regulate water balance in the body and their equilibrium enables them to stimulate nerve impulses for the heart and other muscle contractions. Depletion of either element would depress cell response. The typical American diet of processed and convenience foods do not contain sufficient amounts of potassium creating an imbalance between the two minerals.
Diuretics can cause an excessive urinary loss of potassium. An excess of sodium is related to high blood pressure and fluid retention which taxes the heart and kidneys.