Some controversial and unproven theories
There are several disorders thought by some to be caused by food allergies, but the evidence is currently insufficient or contrary to such claims.
It is controversial, for example, whether migraine headaches can be caused by food allergies. Studies show people who are prone to migraines can have their headaches brought on by histamines and other substances in foods. The more difficult issue is whether food allergies actually cause migraines in such people.
Cerebral allergy is a term that has been given to people who have trouble concentrating and have headaches as well as other complaints. These symptoms are sometimes blamed on mast cells activated in the brain but no other place in the body. Researchers have found no evidence that such a scenario can happen. Most health experts do not recognize cerebral allergy as a disorder.
There is no evidence that food allergies can cause a disorder called the allergic tension fatigue syndrome, in which people are tired, nervous, and may have problems concentrating, or have headaches.
Some people have several, non-specific complaints such as problems concentrating or depression. Sometimes this is blamed on small amounts of allergens or toxins in the environment. There is no evidence that such problems are due to food allergies.
Some people believe hyperactivity in children is caused by food allergies. There is no evidence that a true food allergy can affect a child's activity except for the possibility that if a child itches and sneezes and wheezes a lot, the child may be uncomfortable and therefore more difficult to guide. Also, children who are on anti-allergy medicines that cause drowsiness may get sleepy in school or at home.
There is also virtually no evidence that most rheumatoid arthritis or osteoarthritis can be made worse by foods, despite claims to the contrary.
Controversial and Unproven Diagnostic Methods
One controversial diagnostic technique is cytotoxicity testing, in which a food allergen is added to a patient's blood sample. A technician then examines the sample under the microscope to see if white cells in the blood "die." Scientists have evaluated this technique in several studies and have not been found it to effectively diagnose food allergy.
Another controversial approach is called sublingual or, if it is injected under the skin, subcutaneous provocative challenge. In this procedure, dilute food allergen is administered under the tongue of the person who may feel that his or her arthritis, for instance, is due to foods. The technician then asks the patient if the food allergen has aggravated the arthritis symptoms. In clinical studies, researchers have not shown that this procedure can effectively diagnose food allergies. In addition, these types of challenges could be dangerous if the patient receives foods to which they have IgE antibodies. This could potentially cause anaphylaxis.
An immune complex assay is sometimes done on people suspected of having food allergies to see if groups, or complexes, of certain antibodies connect to the food allergen in the bloodstream. Some think that these immune groups link with food allergies. But the formation of such immune complexes is a normal offshoot of food digestion, and everyone, if tested with a sensitive enough measurement, has them. To date, no one has conclusively shown that this test links with allergies to foods.
Another test is the IgG subclass assay, which looks specifically for certain kinds of IgG antibody. Again, there is no evidence that this diagnoses food allergy.
Controversial and Unproven Treatments
Controversial treatments include putting a dilute solution of a particular food under the tongue about a half hour before the patient eats that food. This is an attempt to "neutralize" the subsequent exposure to the food that the patient believes is harmful. As the results of a carefully conducted clinical study show, this procedure is not effective in preventing an allergic reaction.
Allergy shots have not yet been proven to reliably relieve food allergies.
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Created by the National Institute of Allergy and Infectious Diseases. Modified and updated by A.D.A.M., Inc. Illustration copyright A.D.A.M., Inc.