Bicarbonate of soda is a pure leavening agent. It needs to be mixed with moisture and an acidic ingredient for the necessary chemical reaction to take place to make food rise. Because it needs an acid to create the rising quality, it is often used in recipes where there is already an acidic ingredient present, such as lemon juice, cocoa, yoghurt or honey. Baking Powder should be avoided as it contains additional non GAPS allowable ingredients.