Marshmallow root is one of several ingredients recommended by Dr Hulga Clark in a kidney cleansing formula. It is not however one of the ingredients for the actual cleansing as it is for the side effects of the other herbs in the recipe. Both the root and the leaf of the marshmallow plant contain a substance known as mucilage polysaccharides. This mucusy substance that does not dissolve in water. It is what causes marshmallow to swell up and become slippery when wet. This attribute of the marshmallow plant gives it the ability to soothe irritation of the mouth, throat and stomach, as well as to relieve coughing. Originally it was used to make marshmallows. It was mixed with corn syrup, sugar, gelatin, gum arabic, and flavoring and baked. It then was a medicinal candy given to children for colds and coughs.