Food allergy
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Because of its slow onset, it can be harder to determine the food that caused your sensitivity reaction. In this sense, and because food intolerance used to be called a "pseudo-allergic" reaction, a food sensitivity can be thought of ''kinda-sorta maybe'' as a "hidden food allergy" if you squint at it just right. It's still incorrect to call it a hidden food allergy, though -- there is no immunoglobulin response, and exposure to tiny amounts tends not to trigger a reaction the way it does with real allergies. | Because of its slow onset, it can be harder to determine the food that caused your sensitivity reaction. In this sense, and because food intolerance used to be called a "pseudo-allergic" reaction, a food sensitivity can be thought of ''kinda-sorta maybe'' as a "hidden food allergy" if you squint at it just right. It's still incorrect to call it a hidden food allergy, though -- there is no immunoglobulin response, and exposure to tiny amounts tends not to trigger a reaction the way it does with real allergies. | ||
| − | Finally, confusing the matter even further, there is a conflicting set of terminology in use for non-IgE reactions (reactions that aren't mediated by immunoglobulin E). Some sources call a non-IgE mediated reaction a "non-IgE mediated allergic reaction"; other sources don't classify such an immunological response as an allergy at all. Whether a given non-IgE mediated food sensitivity is called a food allergy or a non-allergic food hypersensitivity seems to be a matter of whoever is is writing the study. | + | Finally, confusing the matter even further, there is a conflicting set of terminology in use for non-IgE reactions (reactions that aren't mediated by the immunoglobulin E antibody). Some sources call a non-IgE mediated reaction a "non-IgE mediated allergic reaction"; other sources don't classify such an immunological response as an allergy at all. Whether a given non-IgE mediated food sensitivity is called a food allergy or a non-allergic food hypersensitivity seems to be a matter of whoever is is writing the study. |
== See also == | == See also == | ||
Revision as of 23:27, 29 October 2012
| Deliciously edible! |
| Dubious diets |
| Food woo |
A food allergy is an allergic reaction -- sometimes life threatening -- to certain foodstuffs.
Several woo meisters have claimed that food allergies are responsible for every malady a person can experience, from fatigue to impotence.[1] Although fewer than 4% of adults actually have food allergies, as many as 25% of adults believe they have food allergies, which feeds into this suspicion.
There is a certain amount of relation to gastronomic disorders and intolerances, (such as lactose or fructose intolerance), but these conditions are not true 'allergies.' Rather than being autoimmune reactions, they are dysfunctions of digestion, such as lack of appropriate enzymes to break down some substances, or easily irritated GI tracts that respond badly to certain foodstuffs.
Contents |
Hidden allergies
One highly dubious claim that's been repeated more than once is that, even if you have no allergic symptoms whatsoever, you might still have "hidden allergies" (usually to certain foods) that are causing all the problems in your life.
How do you tell if you have one of these "hidden allergies"? Why, take the special hidden allergy test provided by the woo peddler, of course! Or, if he doesn't offer testing services, perhaps he'll tell you not to take chances and just assume that all your problems are because you're allergic to corn, soybeans, tuna, peanuts, tree nuts, gluten, shellfish, bananas, household cleaners, bed linens, and air, and would you please sign his petition against Monsanto because they're big and evil?
On one episode of the Dr. Oz Show, he claimed that if you have a hidden allergy to a food item, you might have no symptoms whatsoever immediately after eating something you're secretly allergic to, and then three or four weeks later, pow, you start getting a whole bunch of unpleasant symptoms. He demonstrated this by pouring water on a piece of pink paper and setting off some small delayed-detonation pyrotechnics on his demo table, thereby proving beyond a shadow of a doubt that everything he was saying must be true.
Dubious tests
Cytotoxic testing[2] was popular in the 1980s, and was every bit as accurate as the E meter.
ELISA/ACT, like cytotoxic testing, looked at the reaction of the subject's lymphocytes in vitro to alleged allergens to find "hidden allergies." It operated under the false assumption that an immune response was synonymous with an allergy. The name is unfortunate, because ELISA is also the name of a legitimate test for certain infectious diseases, and the name of a class of protocols used in the process of discovering new pharmaceuticals by drug companies.
The Mediator Release Test (MRT) is another test you'll only see promoted by "alternative" medicine vendors, like the LEAP program and some chiropractors. It tests your reaction levels to 250 foods by putting foodstuffs into samples of your blood and looking for immune cell responses. Several sites reference a "blinded peer reviewed scientific study" which showed MRT to have 94.5% sensitivity and 91.8% specificity. The study in question comes from the journal Przeglad Pediatryczny (1997, Supplement 1, pp. 61-65), published by the Polish Pediatric Association; this journal contains both original research and studies originally published elsewhere and is rather difficult for English speakers to track down. Even if the data are from a well-designed experiment with a large sample size, it might only mean that the test has a 90+% sensitivity and specificity to immune cell responses; how such responses correlate with actual food allergies or intolerances might not have been discussed at all.
Skin-prick tests are the preferred method used by real allergists to discover allergies. They work pretty well for detecting sensitivity to environmental allergens (e.g. pollen and dust mites), but can be of dubious merit where food allergies are concerned.[3] They, and their cousin-German the CAP RAST blood test[4], are both very sensitive but not very specific. This means that there is a great danger of a false positive, particularly if the subject has other allergies.
Food sensitivity
Also known as food intolerance, or non-allergic food hypersensitivity[wp]. These are catch-all terms for a broad spectrum of reactions brought about by foodsuffs, whose only thing in common is that they're not food allergies.
Among the conditions that qualify as food sensitivities (but not food allergies) are:
- gluten intolerance (but not the Celiac disease that may underlie it)
- lactose intolerance
- fructose malabsorption
- salicylate sensitivity
Frustrtingly, the symptoms for food intolerances tend to be very similar to the symptoms for food allergies. Hives, mouth ulcers, nausea, gas, diarrhea, and even (depending on the sensitivity in question) anaphylaxis. The main outward difference is the speed of the reaction: food allergies tend to kick in almost immediately upon exposure, but food intolerances can take anywhere from half an hour to 48 hours to show symptoms.
Because of its slow onset, it can be harder to determine the food that caused your sensitivity reaction. In this sense, and because food intolerance used to be called a "pseudo-allergic" reaction, a food sensitivity can be thought of kinda-sorta maybe as a "hidden food allergy" if you squint at it just right. It's still incorrect to call it a hidden food allergy, though -- there is no immunoglobulin response, and exposure to tiny amounts tends not to trigger a reaction the way it does with real allergies.
Finally, confusing the matter even further, there is a conflicting set of terminology in use for non-IgE reactions (reactions that aren't mediated by the immunoglobulin E antibody). Some sources call a non-IgE mediated reaction a "non-IgE mediated allergic reaction"; other sources don't classify such an immunological response as an allergy at all. Whether a given non-IgE mediated food sensitivity is called a food allergy or a non-allergic food hypersensitivity seems to be a matter of whoever is is writing the study.