The following is information about Leavening Agents, specifically Baking Soda.  Please be aware that bread products containing baking soda should be avoided if there is an acid (which more than likely there will be) in the product.

Any acid may serve as the chemical reaction in foods. Some food substances contain acids which, in the presence of baking soda release carbon dioxide.

Acids can come from many different sources. Baking soda is sodium bicarbonate.  When it is mixed with an acid liquid it releases the gas carbon dioxide: You've seen this- when you mix baking soda with vinegar or lemon juice, it fizzes. The fizzing is the release of the carbon dioxide bubbles. The same thing happens when you add baking soda to a recipe.  Recipes that use baking soda for leavening always have an acid somewhere.  It might be obvious, such as vinegar (in muffins), lemon juice, sour milk or buttermilk. The acid might be hidden- for example honey and molasses are acidic. Cream of tartar is a DRY acid that might be called for in a recipe; it cannot react with the baking soda until liquid is added.