Food allergies are usually exaggerated types of immune system responses that are triggered by specific foods. Normally, the immune system works to defend the body against possibly harmful types of substances, toxins, viruses and bacteria. However, some people have defence reactions against certain foods, causing the body to produce immunoglobulin type antibodies to fight off the alleged invader. Though many have intolerances towards foods, food type allergies are not as common. In fact, a genuine food allergy also produces histamines that cause the body to react quickly to the allergen (s).