A basic question arises regarding all types of sweetened or seasoned baked goods: With what were they sweetened or seasoned, and which other ingredients do they contain? Even when the manufacturer is required by law to specify the ingredients of a product, the list in most cases will not include ingredients of minute quantities, and it also will not specify the manner of preparation of the product. Therefore, when buying such baked goods, one must make sure that they include the stamp of a reliable kashrut agency. Since it is impossible to know which ingredients are present in any product, and since a product can become non-kosher simply by being produced on non-kosher equipment, even plain bread requires kosher certification.

The Sages prohibited one to eat bread produced by a non-Jew. This prohibition was not applied to bread that is mass produced by a professional baker. However, bread produced in a private non-Jewish home is prohibited, even if one knows that the ingredients and equipment used were all kosher. Some are stringent and will not even eat bread baked in a non-Jewish bakery unless the oven was lit by a Jew.