Food sensitivity or food hypersensitivity is a reaction to food that occurs due to intolerance of certain types of food. It is not to be mixed up with food allergies which occur due to the presence of certain chemicals. A food allergy is something that happens as a result of immunological hypersensitivity. This is caused as a reaction mainly to proteins and immunoglobulin that are present in food such as eggs and meat.
Food sensitivity is usually more chronic but less acute. It is not as easy to identify as it is less obvious in its presentation. In the case of an allergy, the reaction is immediate, but in case of sensitivity or intolerance, the reaction is spread over a long period of time. This is the main reason that the cause and reaction are not easily relatable. Food intolerance can be manifested as skin reactions, gastrointestinal reactions, or respiratory reactions.
Food intolerance is tested and identified by checking the medical history, and by administering cutaneous and serological tests. The final confirmation, however, has to be done by a Double Blind Controlled Food Challenge. A Double Blind Controlled Food Challenge is one of the most reliable tests and diagnostic tools that is available for testing food sensitivity. In this test, the patient is asked to ingest two sets of food, one that contains the suspected allergen and one that does not. In this case, neither the doctor nor the patient is sure as to which is the food allergen.
Food challengers in the test are used in a similar way as in elimination diets. Since the patient does not know what the capsule contains, his reaction or lack of it will confirm what he is sensitive to. If the patient reacts consistently to the allergen but not to the capsule, the test is reliable.
The placebo test works by administering the allergen in a concealed form so that the patient cannot identify whether he has consumed it or not. Usually, this is in the form of a capsule in which the allergen is in free matrix. Half the time, during the testing, the patient is not administered the allergen, instead he is given sugar pills. A capsule is given every half an hour to one hour at the discretion of the doctor.
The entire testing is done for about 5 hours. During this time the patient is observed for symptoms and reactions. The test ends when the symptoms appear in the patient.