Although 30% of the population think thay have a food allergy, only 5% actually do – analysis of the research
As part of a large project organised by the National Institute of Allergy and Infectious Diseases to try to impose order on the chaos of food allergy testing, an analysis of research papers on food allergy has been carried out by the University of California, Los Angeles under Dr Marc Reidl.
For the report, Dr Riedl and his colleagues reviewed all the papers they could find on food allergies published between January 1988 and September 2009 — more than 12,000 articles. In the end, only 72 met their criteria, which included having sufficient data for analysis and using more rigorous tests for allergic responses. They found that, despite 30% of the population believing that they have food allergies, only 8% of children and around 5% of adults genuinely suffer from allergy. Indeed, less than 50% of those who reacted positively to skin prick or blood tests, when challenged with the suspect food, proved to actually be allergic to it.
'Part of the confusion is over what is a food allergy and what is a food intolerance', said Dr Matthew Fenton, who overseas guidelines project for the Institutes. 'Allergies involve the immune system, while intolerances generally do not. For example, a headache from sulfites in wine is not a food allergy. It is an intolerance. The same is true for lactose intolerance, caused by the lack of an enzyme needed to digest sugar in milk.'
And other medical conditions, such as acid reflux, can also be confused with food allergies.
The chairman of the guidelines project Dr. Joshua Boyce, said one of the biggest misconceptions some doctors and patients have is that a positive test for IgE antibodies to a food means a person is allergic to that food. It is not necessarily so. During development the immune system tends to react to certain food proteins, producing IgE antibodies but “these antibodies can be transient and even inconsequential.” There are plenty of individuals with IgE antibodies to various foods who don’t react to those foods at all.
The higher the levels of IgE antibodies to a particular food, the greater the likelihood the person will react in an allergic way. But even then, the antibodies do not necessarily portend a severe reaction. Antibodies to some foods, like peanuts, are much more likely to produce a reaction than ones to other foods, like wheat or corn or rice. No one understands why.
The guidelines panel hopes its report will lead to new research as well as clarify the definition and testing for food allergies.
The paper was published in The Journal of the American Medical Association.
Courtesy of the New York Times
First published in May 2010