Originally baking powder was made from baking soda (sodium bicarbonate) and creme of tartar (tatric acid),like ours is. For the chemists in the kitchen, the baking soda is alkaline and the creme of tartar is acidic. When the two are combined and liquid is added a chemical reaction happens, carbon dioxide is made and the product will rise (i.e. acts as a leavening agent). As creme of tartar is quite costly, the food manufacturing industry took it upon itself to find cheaper, alternative acids to creme of tartar. This is when aluminium based acid products were introduced and used as alternatives to traditional baking powder. A lot of people are nervous about a possible connection between aluminium and Alzheimer's disease.