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Bob Lloyd
Skeptic Friend
Spain
59 Posts |
 Posted - 11/11/2009 : 10:43:17
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Given that scratch tests often generate as much as 50% false positives, that far more people claim allergies than have them, and that it's become almost as chic as Gucci to have a dietary problem, is it really all part of the same Woo syndrome as the stuff about detox and supplements?
I suspect many of those suffering from allergies are simply inadequately diagnosed especially since an elimination test will take months if not years to conduct properly. At the same time, there's probably an anxiety-induced group in which the conflicts and stresses of an emotional nature result in immunological over-reaction.
But even allowing for that, is the incidence of allergies really going up? I've been in a group of eight people which contained a coeliac, someone nut-allergic, someone allergic to milk products, and someone allergic to eggs. The chances of that happening given their recorded incidence is around 1 in 5500. Either I was incredibly lucky, or some folks are claiming to have illnesses they don't have, or... the incidence of allergy really is climbing dramatically.
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Kil
Evil Skeptic
USA
13477 Posts |
Posted - 11/11/2009 : 16:16:28 [Permalink]
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I don't know about the false positives, but I had the scratch test when I was a kid, and then went through the series of shots for allergy. And while I am still allergic to some things, all in all the shots seem to have worked. But in all honesty, I can't really say how they worked. Placebo? Maybe. But the doctor was a real allergist.
As for what's going on now, I have no idea. But allergies do seem like they would be a perfect target for woo. |
Uncertainty may make you uncomfortable. Certainty makes you ridiculous.
Why not question something for a change?
Genetic Literacy Project |
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Zebra
Skeptic Friend
USA
354 Posts |
Posted - 11/12/2009 : 02:29:26 [Permalink]
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Are you specifically referring to "food allergies", or are you including other allergic conditions such as allergic rhinitis and, in some cases, asthma? (Not all asthma is related to allergies, but some is; reaction to cockroach allergens is thought to be a common cause in some parts of the country. And the death rate from asthma is higher than it used to be.)
Clearly, there's a fair amount of "over-attribution" to allergy as a term, esp. re foods. (It seems likely that naturopathy may feed into this, but that's currently an unfounded claim on my part.) However, there have also been changes in exposure rates to certain allergens (notably peanuts), and there are now better tests for other allergic conditions (notably celiac disease).
Re "food allergies":
- The prevalence of celiac disease (gluten intolerance) is estimated to be ~1% (may vary by population), far higher than previously thought. Reason for change in estimated prevalence is the availability, now, of serum testing for the various antibodies associated with this condition, rather than having to do small bowel biopsies to make the diagnosis.
- "Wheat allergy" also exists but is less common. Classically, for some reason, it causes exercise-induced hives.
- Nut allergies are common, esp when peanuts are included (botanically, they're legumes). Peanut allergies have risen, attributed to babies being exposed to small amounts of peanut proteins in mom's breast milk. (The widespread consumption of peanuts is a relatively recent occurrence, historically). Blood levels of antibodies to various nuts can be checked. I haven't looked for the data but would guess this type of testing may be more reliable for confirming a person's report of allergic-type reaction to a food.
- Clearly, MANY people who find certain foods don't sit well with them, or who attribute certain symptoms to one or more class of foods, claim that they are "allergic" to the food. For example, lactose intolerance is common, and some people with this say they are allergic to milk. I run into lots of people who don't like eggs (feel nauseated or gross after eating them) who claim they are allergic to eggs, but their symptoms really are not allergic. (This becomes important to sort out when considering whether or not they can safely receive a flu shot).
Personal note: I don't consider myself a kook, and since I work in medicine I run into people all the time who claim they're allergic to a whole list of allergies (or even medications), when true allergy is quite unlikely. I don't walk around saying I have allergies all the time. However, quietly, I've developed allergies to a long list of nuts, raw fruits, and raw vegetables over the years - these are allergic-type reactions in my mouth (and, systemic "anaphylactoid" reactions - not as bad as anaphylaxis - to a few foods, notably peanuts and raspberries). This is quite a bummer. It would be nice to be able to enjoy some fresh berries or crunch on a stick of fresh celery again. However, if the foods are cooked they're OK (except peanuts), so it's not an unsurmountable issue. I also have allergic rhinitis, which - it turns out - is related to the food allergies (see link below) - as well as asthma.
This type of food allergy, oral reaction to raw fruits & vegetables and nuts, now has a name, Oral Allergy Syndrome, but that condition "didn't exist" when I described my symptoms & the trigger foods to an allergist about 25 yrs ago (it didn't exist because it hadn't been recognized & named). The allergist looked at me like I was a major kook. He did, however, order RAST blood tests for all the foods I said I was allergic to, that the lab could test for. I went back a few weeks later to get the result & his tune had totally changed - I had elevated IgE levels against every food he'd tested, except the ones where I told him that whether or not I reacted depended on variety (notably, apples). The levels were highest for the foods I told him were the worst, and lowest (but still elevated) for the foods I told him I only got mild reactions to. Poor guy, he was all of a sudden interested in my "case", whereas I was kind of disgusted because he so clearly hadn't believed me at the first visit. (So, now I've had a chance to be in his shoes on more than one occasion, and hear all about things people think are allergies."
Long aside, & more personal info than I usually give, just to try to show that not ALL "allergy sufferers" are just wishin' it were so...
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I think, you know, freedom means freedom for everyone* -Dick Cheney
*some restrictions may apply |
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Bob Lloyd
Skeptic Friend
Spain
59 Posts |
Posted - 11/13/2009 : 09:30:10 [Permalink]
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It's a really sensitive issue because many people are very defensive about their condition. Presumably, with a lot of people doubting their veracity, they feel vulnerable to the charge of making it up. But the other side of the coin is that many people believe what they are told and if someone they trust tells them they're allergic to something, that's enough for them.
In the case of scratch tests, the level of false positives is so high as to render the tests unreliable given the incidence levels of the allergies. What critically affects the accuracy of the positive result on these tests is both the sensitivity of the test but also the incidence level. If the incidence level is low, the number of wrong positive results from those who don't have the allergy completely swamps the correct positive results from the small number who do. So there are loads of people who have positive scratch tests who wrongly believe they are allergic to some particular substance.
The other factor which needs to be taken into account is the consequence of anxiety in generating an allergy-like response. This is seen for example in people who say they have a cat or dog allergy. Frequently it is the anxiety which causes the reaction rather than anything physical about the cat or dog. The reactions are none the less real for that of course. But with a lot of media attention and commercial pressure focussing on allergies, it's understandable that many people attribute mild symptoms to something deeper.
My guess is that for a lot of people, it's a convenient way of becoming a little more special. That really doesn't help those people who genuinely have allergic reactions, since the shadow of doubt falls on them too. |
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filthy
SFN Die Hard
USA
14408 Posts |
Posted - 11/20/2009 : 05:52:28 [Permalink]
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It has not been diagnosed, but I think that over the last decade I have become allergic to my cat. These days, I hack up a lot of phlegm.
Allergy scams are quite common and lucrative, and it wouldn't surprise me at all if the major drug companies were running a few, what with the various nostrums we see advertised ad ennui.
Here's 10 doozies:
Top 10 retarded allergy treatment scams
Allergies effect nearly 20% of Americans whose bodies respond abnormally to usually harmless substances in the environment. With such a wide range of allergic reactions it’s impossible for medicine to treat all of the symptoms leaving many searching for effective treatments. Here are the most dubious scam treatments you should avoid like the plague..
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If I am indeed allergic to my cat and all this disgusting loogie-spitting is not a symptom of advancing age, I'm screwed. I'm all but convinced that the animal is immortal and I'll still be wheezing at my sky burial. 
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"What luck for rulers that men do not think." -- Adolf Hitler (1889 - 1945)
"If only we could impeach on the basis of criminal stupidity, 90% of the Rethuglicans and half of the Democrats would be thrown out of office." ~~ P.Z. Myres
"The default position of human nature is to punch the other guy in the face and take his stuff." ~~ Dude
Brother Boot Knife of Warm Humanitarianism,
and Crypto-Communist! 
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Kil
Evil Skeptic
USA
13477 Posts |
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Allergies on the rise?
