Taboo
Many world religions have taboos about food.  Islam and Judaism both say there are some foods which people should never eat.  A halal diet does not include any of the foods that are taboo in Islam.  A kosher diet does not include any of the foods that are taboo in Judaism.  Other religions say that people should be vegetarians.  In these religions, eating meat is taboo. Many societies also have taboos about food.  For example, cannibalism is taboo in most societies in the world.