Although water and the principal electrolytes (sodium, potassium, and chloride) are often excluded from lists of nutrients, these substances are essential dietary components, in that they must be acquired from the diet either exclusively or—in the case of water—in amounts well in excess of that produced by metabolism in the body. Concerns about possible overconsumption (sodium and chloride) or underconsumption (potassium) of these substances in the United States are comparatively recent (NRC, 1989; Tobian.
