Some people use "sodium" as a synonym for salt, I think. However, sodium itself is vital for osmoregulation (in small quantities - too much is unhealthy); thing is, it's highly reactive, so sodium chloride (that is, salt) is the easiest way to get access to a form of it that doesn't do nasty things when it encounters water. Even so, it's listed as sodium in the nutritional information labels on food in some areas.
 "Medieval Chronicles 6"){kind=icon}