There are only two substances that humans routinely consume that do not originate from a plant or animal. They are salt and water.
Common salt (sea salt) is sodium chloride (NaCl), but the term salt is used in science to refer to any compound that combines a base and an acid (eg. magnesium sulfate, sodium sulfate).
Excess salt in the diet causes kidney stress and water retention which results in weight gain. Salt should not be added to food in western societies as we get too much already in most processed foods.
(Last modified: 7th Oct 2014)