With food allergies, much is said but little is known, conclude researchers

Food allergies are a problem, especially if you want answers. Just ask often-confused consumers -- or the researchers who recently tried to put a finer point on the topic.

In their noble attempt to establish the prevalence, diagnosis, management and prevention of food allergies, researchers at Stanford University, Rand Corp. and the Veterans Affairs Palo Alto Healthcare System searched databases, analyzed reviews, assessed controlled trials and compared sample sizes. Their conclusion largely seems to be: What a mess.

Or in their words: "There is voluminous literature related to food allergy, but high-quality studies are few. Prime needs for advancement of the field are uniformity in the criteria for what constitutes a food allergy and a set of evidence-based guidelines on which to make this diagnosis."

Their review of food allergy research was published in the May 12 issue of the Journal of the American Medical Assn. 

For starters, the researchers found, there is no agreed-upon definition of food allergies. The National Institute of Allergy and Infectious Diseases, which funded their work, endorses this definition: "an adverse immune response that occurs reproducibly on exposure to a given food and is distinct from other adverse responses to food, such as food intolerance, pharmacologic reactions, and toxin-mediated reactions."

Works for me -- but not apparently for everyone. Such a definition wasn't used in all the research on the matter.

If researchers can't even agree on the definition, you can see how finding common ground on prevalence and diagnosis may be a problem. And as for management ...

Good luck.

The researchers did establish that food allergies affect more than 1% or 2% of the population (but less than 10%). They couldn't confirm, as many believe, that such allergies are actually increasing; nor could they prove that elimination diets will work, even for non-life-threatening reactions. Immunotherapy? It seems promising, but again, no one can say (yet, at least) that it will offer long-term, or safe, relief.

Suffice to say, people allergic to a specific food -- or who think they're allergic to a specific food -- shouldn't expect hard and fast guidance any time soon.

Here's Stanford University's press release on the review, plus a post from the school's Scope blog.

In the latter, the writer recalls a former schoolmate's allergy to milk at a time when food allergies seemed rare. (That's hardly the case now.) My family, on the other hand, was more familiar with the confusion in the food allergy field. An otherwise charming relative blamed it for the loud and seemingly endless throat-clearing after every indulgence of hot-fudge sundae cake -- indulgences that, in retrospect, were surprisingly frequent. Only as an adult was she tested for allergies. Only as an adult did she come to realize she'd bedeviled us all for no reason whatsoever -- no reason having to do with food allergies in any case. Some allergies are outgrown, yes; this apparently was not the case here.

(As for you, Mr. Allergic to Milk but Not Almost-Shocking Amounts of Ice Cream ... let's just say, I'm skeptical. Charmed in an amused way but skeptical. ...)  

But I digress. Here's an L.A. Times story of a few months back explaining in more traditional form why allergies are overdiagnosed, confused and what-not: Think you have food allergies? Think again

As that story states:

With a glut of nonspecialist doctors now offering allergy testing to patients, results that can be difficult to interpret, symptoms that can be wide-ranging and people's insatiable need to find explanations for whatever ails them, foods are frequently blamed for crimes they did not commit.

Though allergies or intolerances (and recognition of them) do appear to be on the rise, there are far more people who erroneously think they have problems with specific foods.

Here are two related stories: Accuracy of allergy tests varies and Cause of rise in real food allergies is unclear.

And here's more on the promising but still unproved immunotherapy: Therapy to suppress peanut allergies is reported: "By taking small but increasing doses of the food, five children can now freely eat items containing peanuts, an allergist says in presenting the results of two clinical trials."

As for people who do, in fact, have food allergies -- which can be life-threatening and thus are not to be taken lightly -- the Food Allergy & Anaphylaxis Network offers advice on how to protect against foods blamed for 90% of such allergies: milk, egg, peanut, tree nuts, fish, shellfish, soy and wheat.

It offers a wealth of other resources as well, as does MedlinePlus' overview of food allergies. Check out the latter's distinction between food allergy and food intolerance. It's one of the issues that make hard and fast answers in this field so difficult. The National Institute of Allergy and Infectious Diseases, meanwhile, offers a rundown of allergy research.

Then sign up to receive emails from the Food and Drug Administration about recalls and safety alerts. Often, products are pulled from store shelves because they contain undeclared allergens. For most people, consuming them wouldn't be a problem. For some people, it could prove deadly.

With researchers still trying to get to the bottom of food allergy prevalence and management, consumers shouldn't become food-allergy hypochondriacs, but they should try to protect themselves as best they can.

-- Tami Dennis

Photo: Allergic to milk? Sensitive to it? Or just don't like the stuff? Sometimes, it's hard to say. (This is soy milk, FYI -- offering double the confusion.)

Credit: Anne Cusack / Los Angeles Times

Comments

[Maria]

I don't understand - and none of the links explains - why I have the exact same symptoms from ingesting certain foods, as I do from breathing ragweed pollen, yet some doctors insist the latter is an allergy but the former is not. Luckily for me I work with an allergist who does believe that they are all allergies.

[Kelly]

Both my kids have food alergies. What I don't understand is why they label adult food with allergens but not baby food. I spend alot of time in the baby aisle trying to see if there is a hidden allergen in the food. With so many babies and toddlers with allergies, why isn't this regulated better.

[Bonnie Minsky MA, MPH, CNS, LDN]

I have so many clients who think they have food allergies (IgE), but instead have food intolerances (IgG), which are cyotoxic, not immunologic, responses to food.

[Rob Reinhardt]

There is a difference between sensitization and true clinical allergy, and determining which patients are sensitized and which are truly allergic is a challenge for doctors. Current skin and blood tests measure the body’s IgE or sensitization to allergens, but a positive result does not necessarily mean a patient will have a serious reaction.

The science of allergy testing is evolving. With allergen component testing, the antibody response can be tested against specific molecular level protein components of the allergen, in order to provide additional specific information about the various IgE antibody populations. This knowledge, in conjunction with ongoing research, will soon aid in a clinician’s overall assessment of a patient. ImmunoCAP Allergen Components are expected to allow specialists to pinpoint those patients who are at risk for true food allergies.

Specific IgE to one peanut protein component, Ara H 2, has been shown as a prime culprit of a potentially serious clinical response to peanut 97 percent of the time, but is only present in about ¼ of the patients having tested positive to the entire peanut extract using traditional skin or blood tests. Molecular level testing will soon allow discrimination between clinical sensitization and potentially serious, true clinical allergy.

Allergists need a wide range of information, including patient history, blood and skin tests, and challenge tests to help patients and parents understand the allergic process. Allergen component testing adds another critical tool to the food allergy diagnosis toolkit.

Rob Reinhardt, MD

Senior Director

Medical, Regulatory & Quality

Phadia US Inc.

Associate Professor

Michigan State University

www.KnowYourIgE.com

www.pirllab.com

[smilinggreenmom]

Food allergies are so hard to figure out! Our son has food allergies and food intolerance that causes severe Eczema. The only thing that has helped him dramatically has been his probotic for kids called Belly Boost. We are so thankful to have found it! However, we do still avoid his serious allergens and have yet to find a doctor who can really help.