Dietary Restrictions
Food manufacturers are sometimes reluctant about informing consumers about the source from where the flavor is obtained and whether it has been produced with the incorporation of substances such as animal by-products glycerin (note that glycerin is also available from vegetable sources), gelatin, and the like, and the use of alcohol in the flavors. Many Jews, Jains, Hindus, and Muslims adhere to religious dietary laws, and vegans to personal convictions, which restrict the use of animal by-products and/or alcohol in foods unless subject to oversight and inspection by their respective religious authority or less-strict or circumstantial moral belief. In many Western countries, some consumers rely on a Jewish Kosher Pareve certification mark to indicate that natural flavorings used in a food product are free of meat and dairy (although they can still contain fish). The Vegan Society's Sunflower symbol (which is currently used by over 260 companies world wide) can also be used to see which products do not use any animal ingredients (including flavorings and colorings)
Similarly, persons with known sensitivities or allergies to food products are advised to avoid foods that contain generic "natural flavors" or to first determine the source of the flavoring before consuming the food. Such flavors may be derived from a variety of source products that are themselves common allergens, such as dairy, soy, sesame, eggs, and nuts.
Read more about this topic: Flavors