Sodium is an essential biological element to the more advanced animals; the ratio sodium/potassium concentrations in intercellular and extracellular fluids is responsible for the transport ions through the cellular membranes, the regulation of the osmotic pressure inside the cell, the transmission of nervous pulses and other electrophisiological functions.
Since there no reserve store of sodium ions in the animal body, losses above the amount of intake come from the functional supply of cells and tissues. This depletion results in serious symptoms and even death. Thus, the importance of NaCl in nutrition has been recognized since prehistoric times. Human populations living on grains, vegetables and fruits experience a salt hunger that causes them to got to great lengths to obtain salt. Sodium deficiency may result from extreme excretion of sodium ion by sweating and other loss of body fluids. It is evidenced by thirst, anorexia and nausea. Other results of severe sodium loss are lassitude, muscle cramps and mental disturbances.