I love bread, but I'll give it up if I have to
February 23, 2010 12:36 PM   Subscribe

How useful are skin tests at identifying food allergies?

I had allergy testing this morning, and one thing I tested positive for was wheat. The allergist was surprised by this finding, because she didn't think it fit my symptoms, but she would like me to do a 6-8 week elimination diet to see if it helps.

I am trying to decide whether the elimination diet is worthwhile. Reasons I'm not sure:

1. I did an elimination diet 2-3 years ago, for different reasons (trying to identify triggers for my chronic headache), and it made no difference. But clearly some things have changed for me in that time (I have symptoms now I didn't have then), so a repeat might not be a bad idea.

2. Just today I saw a story about physicians using food challenges and finding that many children whose peanut allergies are identified by skin tests are not actually allergic. Given that, and my history of doing a previous elimination diet, I'm not sure how seriously to take the results of this particular test.

3. Mmmm, bread.

So, two questions:

1. What do you know about the accuracy of identifying food allergies through skin tests?

2. If a previous elimination diet didn't show a problem with wheat, is it likely that things have changed enough that a repeat of the diet might show something different? Have you repeated an elimination diet with different outcomes?
posted by not that girl to Health & Fitness (8 answers total) 6 users marked this as a favorite
I have some info for you about food challenges instead of blood tests/elimination diets for diagnosis of food allergies from where I work. I will Mefi Mail you.
posted by Kimberly at 12:52 PM on February 23, 2010

and by blood tests I meant skin prick tests :)
posted by Kimberly at 12:59 PM on February 23, 2010

I don't know anything about wheat allergies, but I got tested a year ago because I was (an am) certain I'm allergic to citrus foods. The skin test only showed a very minimal reaction, but eliminating it from my diet proved I was right. Unless your symptoms are very severe, and will require extra medical attention, I don't see why you wouldn't consider a short elimination diet trial.
posted by Unred at 1:53 PM on February 23, 2010

I don't know anything about wheat allergies, but I got tested a year ago because I was (an am) certain I'm allergic to citrus foods. The skin test only showed a very minimal reaction, but eliminating it from my diet proved I was right.

Anecdotal, but for what it's worth - my father has the opposite situation with citrus. He's been known to eat grapefruit while wearing rubber gloves because he has an extreme reaction to it on his skin but it causes no noticeable reaction from consumption.

So you could very well have a reaction one way and not the other. However I'm with Unred - if this is a situation significant enough to justify doing skin testing then it certainly seems worth trying a diet change. Bread's not going anywhere.
posted by phearlez at 2:00 PM on February 23, 2010

I discovered a food allergy to cinnamon through skin tests, and eliminating cinnamon from my diet has made me feel better and lessened the migraines I used to have.
posted by Dee Xtrovert at 3:04 PM on February 23, 2010

I don't know about wheat, but I had both a skin and blood done last summer, to test for a number of food allergies - namely fruits, vegetables, and nuts associated with OAS (Oral Allergy Syndrome).

The skin/scratch test turned up a number of false positives and false negatives. For example - of the dozen+ things I've had reactions to, I react to apples the worst. The scratch test indicated I had no allergy to apples (!!). The skin test for potatoes and peas also produced some enormous red, itchy as hell bumps - but I have never had any kind of reaction to potatoes or peas, and they are outside of the groups of OAS culprits I react to. I had like 4 other false positives and negatives as well, but these were the most bizarre.

The blood test contradicted the skin test, and matched the patterns of things I've reacted to, and made much more sense. I still avoid apples, and happily eat potatoes and peas reaction free.

Again, I don't know much wheat allergies - but my experience with food allergies would be to get blood work done to confirm whether or not it is something you ought to reduce or eliminate from your diet, as the skin test in my understanding, is not always an accurate indicator of food allergies.
posted by raztaj at 5:18 PM on February 23, 2010

For the accuracy of skin prick tests, Medline Plus Encyclopedia says:
"The accuracy of allergy testing varies quite a bit. Even the same test performed at different times on a person may give different results. A person may react to a substance during testing, but never react during normal exposure. Rarely, a person may also have a negative allergy test and still be allergic to the substance."

Mayo Clinic has a brief page on wheat allergy tests, which include the skin prick, diet elimination, and also a blood test.

From what I have heard from my coworkers with celiac disease and Gluten Free Girl, they took the blood test. It may or may not be covered by your health care provider. BTW I recommend Gluten Free Girl's website if you need to go gluten free & deal with the lack of mmmm bread!

I have allergies to all kinds of stuff too, and I was curious of the actual accuracy of skin prick tests for food/oral allergies. There are some articles on PubMed and Google Scholar (search for skin prick test AND wheat) but I didn't find any good, free & non-technical summaries.
posted by SarahbytheSea at 7:47 PM on February 23, 2010

Sorry, can't help you on the science, but as for #3--

I'm gluten free (wheat free, among others) and it sure as heck does not mean giving up bread. I buy and bake sinfully delicious baked goods. I went through such mourning in the beginning because the dieticians, the books, and the websites all seemed to be warning that alternatives are terribly limited and basically unpalatable. Don't believe it. That info is outdated. The options for gluten free eating have improved radically in just the last couple of years, for a variety of reasons that are too far afield from answering the OP's question. But the bottom line is that you can do the elimination diet if you choose to. Forget about giving up bread being a factor in that decision. (If you decide to do it, memail me. I'd be glad to hook you up with some good brands, sources, books, and recipes.)

If you have any doubt that there is life after wheat, I have three word for you: flourless chocolate cake. Freakin' richest thing you've ever tasted.

The one caveat I will note is that the wheat flour alternatives do come with greater complication and/or expense. But if you have any local ethnic grocery stores (an asian grocery, primarily) and enjoy doing your own baking, the cost can be cut down considerably. Once you get used to some major changes in the way you shop and dine out, the complication also eases considerably.

posted by nakedcodemonkey at 8:24 PM on February 23, 2010 [1 favorite]

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