Pamela A. Popper, Ph.D., N.D.

Wellness Forum Health

According to many medical professionals, the incidence of food allergies is rising, and it is an important reason why people are developing so many diseases. An entire industry has developed to perform tests for food allergies, and many practitioners earn a great living prescribing complicated diets that eliminate dozens of foods, selling supplements that are purported to provide nutritional sufficiency while eating a restricted diet, and administering therapies that are supposed to “cure” the allergies.

While some people really do have food allergies, some quite serious, most people do not. Many of the testing methods used to diagnose food allergies are not reliable and the diagnosis of food allergies in a growing number of people is actually a form of disease mongering. To evaluate whether or not the incidence of food allergies is really increasing, researchers looked at 12,378 published articles on food allergies. Only 72 studies met the criteria of using rigorous testing and inclusion of a sufficient amount of data for evaluation. The researchers concluded after analyzing those that the incidence of food allergy in children is about 8% and the incidence in adults is about 5%, significantly less than the percentage of people claiming to have food allergies or being diagnosed with them. The study was part of an effort by the National Institute of Allergy and Infectious Diseases to develop clear guidelines for the diagnosis and treatment of food allergies.

The test most commonly used to diagnose food allergy is a skin prick tests in which a small amount of a food is injected under the skin and then the blood is tested for IgE antibodies. The problem is that this test is often not a reliable indicator of food allergies. The reason is that many times the immune system will mount a response to certain food proteins, but the antibodies created are harmless and the response is often temporary.

This was confirmed in a study in which oral food challenges were given to confirm food allergies previously diagnosed in 125 children. Most failed to confirm the diagnosis. The researchers concluded that in the absence of anaphylaxis, skin prick and/or blood tests should always be confirmed with an oral food challenge prior to restricting any food.

An oral food challenge involves giving a food to a patient disguised so he does not know what it is and then testing for a reaction. Doctors tend to not like it since it is time consuming, but it is more accurate than IgE testing.

There is considerable over-diagnosis of some people based on faulty IgE testing. But, on the other hand, many people are told they do not have issues with certain foods who clearly do. These people have intolerances to foods or ingredients, but antibody tests are negative. For example, some people get headaches or experience extreme fatigue after consuming food seasoned with MSG, but they will not have an immune response to MSG.

The over-diagnosis of food allergies often diverts attention from real issues that need attention. Many patients are told that their fatigue, hormone imbalances, and other conditions are related to food allergies or intolerances rather than the fact that they are eating diets including large amounts of animal foods and fat, which is a more likely cause of many of their problems.

All in all, allergy testing is an imprecise science, which leaves the door open for poor diagnosticians and opportunistic practitioners to prey upon the general public with expensive tests, treatments and unnecessarily restricted diets.

[1] Schneider Chafem J, Newberry S, Riedl M, et al. “Diagnosing and Managing Common Food Allergies.”

JAMA. 2010;303(18):1848-1856.

[1] Spears G, et al “Over-reliance on serum testing for IgE to food allergens results in inappropriate food elimination diets” J Allergy Clin Immunol 2009; 123: S179.