allergies, intolerances and testing - confused - Mothering Forums
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#1 of 12 Old 10-03-2009, 03:46 AM - Thread Starter
 
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okay - can someone explain to me simply the difference between an allergy and an intolerance, and in what ways either/both are identified?

I have had seasonal and dust and mold allergies forever, and assume myself to be lactose intolerant, but went last week to the dermatolgist for what is evidently eczema and had him draw blood for an allergy test, but then started reading about allergies and intolerances and different kinds of testing and false negatives and positives and don:t know whether the testing will tell me anything at all. wheat allergies a consideration.

am confused - and sure I am overcomplicating matters!

TIA

sara

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#2 of 12 Old 10-03-2009, 04:02 AM
 
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Basically, a food allergy is a problem with the immune system. A food intolerance is a digestive issue.

For instance, people who have a dairy intolerance can still drink things like Lactaid milk. Or take one of those lactose intolerance pills and enjoy their ice cream. The pills aids your bodies digestion, helps overcome the intolerance.

If you were to have dairy, without pills or Lactaid, etc., then you'd have digestive issues - stomach upset, vomiting, gas cramps, etc. This would be your digestive system rebelling.

I don't have a dairy intolerance, but I do have a dairy allergy. I can't ever have dairy. If I have it, my immune system attacks and "battles" the invading food. At which point, I get a severe rash all over my body. Itchy, ugly, painful, and unpleasant.

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#3 of 12 Old 10-03-2009, 10:15 AM
 
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Basically, a food allergy is a problem with the immune system. A food intolerance is a digestive issue.
Not necessarily. A food allergy is an IgE response, and a food intolerance is an IgG response. Some of the symptoms overlap. You can have eczema from either an environmental allergy, food allergy, or food intolerance. You can have vomiting from either. You can have constipation/diarrhea from either. You can have rashes from either. But you have hives or anaphylaxis from an allergy.

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For instance, people who have a dairy intolerance can still drink things like Lactaid milk. Or take one of those lactose intolerance pills and enjoy their ice cream. The pills aids your bodies digestion, helps overcome the intolerance.
If you have a LACTOSE intolerance, it is true that you could have Lactaid milk or take a pill. Or have butter (which is low lactose). If you have a MILK intolerances, you cannot have any of those things because you react to more than just the milk sugar. If you have a milk allergy, you react to the milk protein. If you have a milk intolerance, you react to many of the ingredients in milk (the sugar, the protein, etc.).
[/QUOTE]

So if you have eczema, it can be any of the above mentioned things. If it is an allergy, then the blood testing he's doing may figure it out. I believe that RAST tests are less accurate than skin prick tests. For food stuff, though, the gold standard is an elimination and challenge. You could start a food diary (noting everything including supplements and all symptoms) and see if you can figure it out from there, if it is an intolerance. For eczema, it seems like dairy, corn, and eggs are the main culprits. The top 4 intolerances in general are dairy, gluten, soy and corn. For my DD2 it was corn. I had her allergy tested and an intolerance test, and corn didn't show up on either (though she has other intolerances that did show up), so the tests aren't 100% accurate, for sure. But they can help.

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#4 of 12 Old 10-04-2009, 12:40 AM
 
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Sorry, I meant to say lactose as opposed to dairy. Since I can't eat/drink any of it anyway, I tend to lump it all in the same category. But, you're right - two different things.

The way my doctor explained it - when it's an allergy, your body creates antibodies to fight the "food" you've put in. Usually, the reaction is against the protein. But, not always. Whereas the food intolerance is often a digestive system response - whether from lack of enzymes or other issue. But, obviously, not always. lol ... I guess it's never good to generalize.

I agree about the food diary and elimination diet.

When I did the skin test with dairy - nothing happened. It was negative. Even though "they" say those are generally reliable. But, when I did the blood test - it came out positive. Also, due to my quite obvious reaction, I pretty much knew dairy was the culprit and eliminating it fixed the symptoms for me.

I find the elimination method to be the best. I've done this over the years with various foods, and could definitely tell which foods weren't agreeing with me and which were. I've recently gone gluten free ... and holy heck, what a difference it has made! The elimination method is tedious, though, I must admit.

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#5 of 12 Old 10-04-2009, 06:13 AM
 
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Originally Posted by Sailor View Post
The way my doctor explained it - when it's an allergy, your body creates antibodies to fight the "food" you've put in. Usually, the reaction is against the protein. But, not always. Whereas the food intolerance is often a digestive system response - whether from lack of enzymes or other issue. But, obviously, not always. lol ... I guess it's never good to generalize.
From all that I've read, the jury is still out on what exactly a food intolerance is and how it effects our body. Conventional medicine and science tend to shun the idea that the presence of IgG antibodies to food means anything at all health-wise. This is partly because most people have low level antibodies to many foods and partly because not many scientific studies have shown good evidence that IgG antibodies to foods = ill health from eating those foods.

There have been a few studies showing that removing foods identified in IgG tests help irritable bowel syndrome and at least one study that queried 4,000 patients who used the results of food intolerance testing about health benefits. This is relatively limited evidence overall, though. If IgG antibodies do play a part in ill-health, then exactly how, is still undetermined. If you read the literature from many of the companies who offer these sorts of tests, they claim a large number of health issues (way beyond 'digestive') can be caused by food intolerance.

An unarguable tenet, however, is a positive health effect from food elimination. If you feel better without it, leave it out. We saw a remarkable improvement in our DS when we cut out wheat and this was before we got the results of his IgG test, which indeed, confirmed wheat, gluten and cow's milk sensitivities. I understood the dubious nature of the test (according to science and many allergists anyway) before ordering it but was more convinced of its accuracy when the foods we suspected causing problems in DS (from food journal/elimination) were the same foods that came back positive on the test (with the exception of soy and potato.) My son's bottom went from a constant diaper rash to almost healed in just a few days after eliminating wheat/gluten.

Overall, I think the scientific method is hard to apply when it comes to foods, diet and nutrition. The immune system is complicated and there are parts we still don't understand -- so, science still has a lot to learn about both.

Overall, though, if your doc drew blood, he is likely looking for an IgE antibody. This will tell you if you have a true allergy to a substance. If you do, then you'll have to avoid it completely to prevent possibly escalating and/or serious reactions.

Me (37) ~ DH (39) ~ DS (3) ~ TTC #2 since 4/10
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#6 of 12 Old 10-04-2009, 06:23 AM
 
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Originally Posted by kjbrown92 View Post
If you have a LACTOSE intolerance, it is true that you could have Lactaid milk or take a pill. Or have butter (which is low lactose). If you have a MILK intolerances, you cannot have any of those things because you react to more than just the milk sugar. If you have a milk allergy, you react to the milk protein. If you have a milk intolerance, you react to many of the ingredients in milk (the sugar, the protein, etc.).
I don't think we truly know what the difference is between an allergy and an intolerance. In an allergy, it is possible to identify the protein or component that triggers the allergic response. A food intolerance isn't officially recognized by many doctors/allergists/scientific studies - it could be an intolerance to many different parts of the food. It could be that you are intolerant to only the same protein that someone else is allergic to (in other words, a different part of your immune system responds to the same protein) or it could be that you are intolerant to one or more other components. And, of course, it could be (and this is likely the case) that it is different in every individual. This may be why some people can't tolerate ANY food in a particular family, like nightshades, and other people might be able to eat tomatoes but not potatoes. Many foods in the same family share similar proteins/sugars/compounds. In essence, an allergy is easily pinpointed by science but an intolerance is a vague, loosely defined and likely very different response in each individual.

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I believe that RAST tests are less accurate than skin prick tests.
RAST tests (blood) tend to have false negatives but not false positives. In other words, if a RAST test says you have IgE antibodies to a substance then you definitely have an allergy. It can miss things though. A skin prick test is the opposite. It can have false positives but not usually false negatives. In other words, if your skin swells up because they injected milk under it, you might not *really* be allergic to milk. If no reaction occurs, though, you can pretty much assume you are not allergic to it.

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#7 of 12 Old 10-04-2009, 06:39 PM
 
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The ALCAT test that my kids had doesn't actually have anything to do with IgG, though for some reason I forget that. It measures each food against an inflammatory response in the blood. So it doesn't really specify where that inflammation is: skin, intestines, muscles, etc.

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#8 of 12 Old 10-04-2009, 10:50 PM
 
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The ALCAT test that my kids had doesn't actually have anything to do with IgG, though for some reason I forget that. It measures each food against an inflammatory response in the blood. So it doesn't really specify where that inflammation is: skin, intestines, muscles, etc.
Based on your loose definition, RAST/CAP RAST/Immunocap testing does the same thing, only they're measuring IgE level in response to a certain allergen.
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#9 of 12 Old 10-05-2009, 12:09 AM
 
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Also, if you happen to be taking anti-histamines, wait until they're out of your system before doing the skin prick test. I was doped up on them, and somehow no one asked me if I had been taking them until AFTER the test.

There are really quite a few variables that can affect results.

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#10 of 12 Old 10-05-2009, 08:15 AM - Thread Starter
 
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thanks for the replies, all! a clearer picture is slowly forming and I am now off to try to understand the IgE test results (wheat allergy but only a 3 on a scale of 1 - 6, not quite clear on what that means I ought now to do).

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#11 of 12 Old 10-05-2009, 01:21 PM
 
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thanks for the replies, all! a clearer picture is slowly forming and I am now off to try to understand the IgE test results (wheat allergy but only a 3 on a scale of 1 - 6, not quite clear on what that means I ought now to do).
A 3 on RAST would be considered a "moderate" allergy, but it's definitely an allergic response.

Our allergist considers a 1 to be a negative, and a 2 without a history of anaphylaxis to be worthy of a food challenge.
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#12 of 12 Old 10-08-2009, 05:28 AM - Thread Starter
 
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thanks - moderate is a helpful word! I am working with a language barrier here; between my Japanese, the doctors English and dh sometimes available to translate we get the essentials, but I have trouble asking for clarification.

I went off gluten starting sunday evening (its thursday now) and have def. noticed less bloating already, which is lovely! looking over the possible symptoms, I see lots of small-enough-I-guess-I-can-live-with-it sort of things that I just assumed were normal-ish, or attributed to other causes (mostly my endometriosis) which could actually be attributed to a wheat/gluten allergy. A gluten allergy is decidedly inconvenient, as dh and I own and operate a bakery, but to be rid of the endo pain ... this could be a good thing all in all.

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