Debunking Food Allergies? Not So Fast

 We need better ways to diagnose food allergies, but that doesn't mean they don't exist.An article out of UCLA, published in the JAMA (Journal of the American Medical Association) and heralded by cranky science writer Gina Kolata on the cover of the New York Times as the definitive work on food allergies is based on an analysis of old studies, and will be out of date when the next study is published. The authors' major conclusions--swallowed hook, line and sinker by Kolata--is, "Many who think they have food allergies do not." But the evidence the authors use to make this broad sweeping conclusion is pretty darn flimsy. And it misses the point about the role food plays in immune system reactivity.

Dr. Merrell's Tip: The best way to identify food allergies is to eliminate all possible allergens (most comomonly wheat, dairy, shellfish and strawberries) for one month, and then challenge your body by adding back the allergens one at a time for two weeks each.

They looked at 12,000 peer reviewed journal articles from the last 20 years and decided that they could only believe 72 articles. The rationale they gave for throwing out 11,928 articles deemed worthy by other scientists was primarily that they didn't like the way the food allergy testing was conducted. The JAMA authors prefer less widely used food challenge testing (when a food is removed for a period of time, then reintroduced and reactions observed) to the standard skin prick and antibody blood test that are commonly used to diagnose food allergies. Talk about cherry picking!

At most the conclusions could plausibly have raised important questions about food allergy testing methods, but there is nothing in this study to warrent any solid conclusion about the prevalence of food allergies in the general population. The authors did seem to get pretty puffed up about themselves; one told science-groupie Kolata, "We were approached as in a sense the honest brokers ." Maybe they were encouraged by their own sense of self-importance to over-reach. Honestly guys, calm down.

In a truely surprising stance, the authors dismiss the use of IgE antibody blood tests to look for allergies. This is bascially a test to look for antibodies (sort of ballistic missiles) produced by the body against certain foods that it has incorrectly deemed to be foreign. While IgE testing is not perfect, it can identify subtle allergies before they blow up into something harder to manage. The authors prefer to wait until people develop major rashes or even severe life-threatening anaphylaxis before an allergy is declared. Hard to imagine, though, what could be bad about early intervention.

For the  most part you can ignore this study and the unquestioning report by Kolata (just as you hopefully ignored her gullible rant a few months back about women not getting mammograms.) The only worthwhile nugget from this study is the recommendation to conduct food challenge tests. These are easy, and you can do them at home. If you suspect a food is causing you problems,  elimimante it completely for at least 2 weeks, then eat quite a bit and see what happens. If you are worried about the reaction you may have upon reintroduction, make an appointment to go to an allergist to reintroduce the food.

The role played by food allergies and intolerances is far too important to be steamrolled by a meta-analysis like this one from UCLA. It is crucial for scientists to identify new, precise methods of identifying allergies and sensitivies, which not only can produce symptoms themselves, but can exacerbate other conditions such as eczema, asthma, irritable bowel, fatigue and even hay fever. Or a very wise woman once said, let's not throw the baby out with the bathwater!