An electrolyte, according to the National Cancer Institute, is a substance that breaks up into ions (particles with electrical charges) when it is dissolved in water or body fluids. Some examples of ions are sodium, potassium, calcium, chloride, and phosphate. These ions help move nutrients into cells, help move waste out of cells, and help nerves, muscles, the heart, and the brain work the way they should. They play essential roles in modulating and maintaining key life functioning, such as the functioning of the nerves, muscles, kidneys, GI tract and others.