Marshmallows were originally made with the sap of the root of the marsh mallow plant instead of gelatin. The sap was cooked with egg whites and sugar and whipped into a foam. This foam hardened when cool and was cut up and used as a type of throat lozenge (marsh mallow sap reportedly acts as a cough suppressant). In the late 1800's, the marsh mallow sap was replaced with gelatin, and egg whites were phased out of most mass produced recipes.