Newbie

[CMdeux]

Boo and TwinTurbo have given you excellent advice.

I'd seriously press your allergist on the subject of food challenges to some tree nuts.  Find out (for certain) what you can-- and cannot-- have in your home.  The advice you've been given sounds VERY much like "let them eat cake" coming from your allergist; some of them truly can't quite grasp what it is to live with food allergy, and others can't quite grasp what it means to live with a very low threshold dose (we've had both experiences with allergists, even very good ones).

So ultimately, day-to-day management and avoidance?  Your allergist isn't the expert.  YOU are.

So gather information, but then make your own decisions about risk/benefit, IMO.   


Some allergens we keep in the house, and some we don't.

Not in the house:  crustaceans, cashew, pistachio, peanut-- the reasoning is that the eliciting doses involved are either too unpredictable or too scary-low and/or the reaction history is very, very scary-severe.  A major-- or in a couple of cases, minor-- error with one of those could cause death no matter what transpired afterwards.  So.

Not in the house because they simply don't NEED to be, and they are likely anaphylaxis triggers-- mango and walnut.

Not in the house in some FORMS:  soy, almond, egg.

In the house, just avoidance for those who are allergic-- several things, mostly fruits and vegetables; milk.



I mention this to let you know that most of us have a highly idiosyncratic household protocol surrounding this stuff.   Mostly, it's stuff that we've figured out taking into account our own life experience, the needs and desires of OTHER members of the family, cultural preferences, etc. etc. 

I grew up in a house that did NOT restrict my allergens-- ever.  Now, did that force tolerance?  Well, maybe.   But I developed a shellfish allergy as an adult, and I'd been eating shrimp and other crustaceans regularly my entire life.   

Allergic is allergic, and if you aren't destined to be, then so be it, IMO. 

While topical reactions to things like poison ivy are not in the same category as IgE-mediated food allergy, it's an instructive example--  additional exposure just racks up ticks on your life-o-meter there.  About 80% of people are born with a magic number.  Reach that and you're allergic.  For some unlucky souls, it's 0 or 1.  For some others, it's 987, or 46.  No real way to know until you learn the hard way.

I do wonder about that given the number of ADULTS with nut or shellfish allergy that seemed to develop after a period of exposure.  If exposure is protective then that shouldn't happen-- but it clearly DOES.

[jschwab]

Boo and TwinTurbo have given you excellent advice.

I'd seriously press your allergist on the subject of food challenges to some tree nuts.  Find out (for certain) what you can-- and cannot-- have in your home.  The advice you've been given sounds VERY much like "let them eat cake" coming from your allergist; some of them truly can't quite grasp what it is to live with food allergy, and others can't quite grasp what it means to live with a very low threshold dose (we've had both experiences with allergists, even very good ones).

So ultimately, day-to-day management and avoidance?  Your allergist isn't the expert.  YOU are.

So gather information, but then make your own decisions about risk/benefit, IMO.   


Some allergens we keep in the house, and some we don't.

Not in the house:  crustaceans, cashew, pistachio, peanut-- the reasoning is that the eliciting doses involved are either too unpredictable or too scary-low and/or the reaction history is very, very scary-severe.  A major-- or in a couple of cases, minor-- error with one of those could cause death no matter what transpired afterwards.  So.

Not in the house because they simply don't NEED to be, and they are likely anaphylaxis triggers-- mango and walnut.

Not in the house in some FORMS:  soy, almond, egg.

In the house, just avoidance for those who are allergic-- several things, mostly fruits and vegetables; milk.



I mention this to let you know that most of us have a highly idiosyncratic household protocol surrounding this stuff.   Mostly, it's stuff that we've figured out taking into account our own life experience, the needs and desires of OTHER members of the family, cultural preferences, etc. etc. 

I grew up in a house that did NOT restrict my allergens-- ever.  Now, did that force tolerance?  Well, maybe.   But I developed a shellfish allergy as an adult, and I'd been eating shrimp and other crustaceans regularly my entire life.   

Allergic is allergic, and if you aren't destined to be, then so be it, IMO. 

While topical reactions to things like poison ivy are not in the same category as IgE-mediated food allergy, it's an instructive example--  additional exposure just racks up ticks on your life-o-meter there.  About 80% of people are born with a magic number.  Reach that and you're allergic.  For some unlucky souls, it's 0 or 1.  For some others, it's 987, or 46.  No real way to know until you learn the hard way.

I do wonder about that given the number of ADULTS with nut or shellfish allergy that seemed to develop after a period of exposure.  If exposure is protective then that shouldn't happen-- but it clearly DOES.

I always have felt like shellfish was in its own category, though, since it's almost always adults who develop it and it's rare for people to eat it very intensively (like, every day) except in specific regions near the sea. It's just so common in adults and is almost always adult-onset. If it is related to dust mite exposure as is thought, though, it could just be that people reach their threshold that way. Nuts seem to have a different pathway since first exposure in children can and often does elicit a severe reaction and maybe low-level dosing in a nonallergic kid does make sense? Or would make sense if they could figure out the right dose? I don't think anyone has enough information, though. This is the kind of thing I would really love allergy researchers to pay attention to better. I feel like in my own life I can tell you exactly how my allergies developed in the leadup to anaphylaxis, how long it took, what symptoms I had. But I feel like no clinician can describe that in terms of the physiology of sensitization. The allergist I just saw felt I might have sensitized myself to almonds, but I don't read much in the literature on sensitization. I don't read much about how to "read the signs" of a proto-allergy, per se, even though with every allergy I developed I had some pretty glaring signs in the time leading up to initial anaphylaxis (gastro mostly). With nut allergies, I would personally not trust an "innoculation" model, and also not with shellfish. Although I might with an allergy like milk that seem much more mutable in nature.

[twinturbo]

As far as I know about mite-crustacean cross reactivity I don't think that exists outside of testing. A component test may reveal what protein fractions are shared but the Asia Pacific region is much harder hit with dust mites, they deal with more species due to temperate/tropical climates. It has not correlated positively to crustacean sensitization. Wheat and milk are significant in East Asia, Singapore is also heavy on milk allergy to a special milk carbohydrate along with peanut. The lengthened pollen seasons do seem to correlate to an increased sensitization to fruits and vegetables beyond OAS.

Mainly though, the allergic march there is epidemically sensitized to heinous dust mites with epidemic levels of asthma and eczema. It's possible that the population in USA in isolation correlates with dust mite-crustacean but this does not present as such globally, even in regions with more species and incidences of dust mite population and sensitization. Open access papers and abstracts available in threads I posted to.

[rebekahc]

I think it's a fallacy to assume most shellfish allergy is adult-onset and therefore different from peanut (though there may be research suggesting such that I'm not aware of).  Personally, I know equal numbers of people with adult-onset peanut allergy as I do adult-onset shellfish allergy.  My kids and I are all childhood-onset shellfish allergy.

However, if it's true that shellfish allergy is statistically likely to be adult-onset, then that could suggest the possibility of sporadic exposure leading to sensitization since shellfish allergy isn't more prevalent in coastal regions or populations who consume higher than average quantities of shellfish.  I'd be curious to know if adult-onset shellfish allergy is caused by different protein sensitization (perhaps one in chitin) than the sensitizing protein(s) of childhood-onset shellfish allergy.

[CMdeux]

At least with fish allergy, though-- the demographics DO support a model that suggests that exposure IS the lynchpin for development of the allergy.    It is most common (at least in Caucasian ethnicity) in countries where fish is a regular, even ubiquitous, part of the diet.

Sesame, same thing-- it's most common in cultures where it is pretty ubiquitous in the diet (Middle East), and less so in places where consumption is sporadic (as in N. America).

[rebekahc]

In your examples, has there been a causal relationship found or could it just be that higher rates of exposure result in higher rates of diagnosis?  Are the rates higher for just adult-onset or is it childhood-onset (perhaps due to earlier exposure in ubiquitous consumption diets)?

Really not trying to argue with anyone...just thinking out loud and asking out of curiosity...I have done no research on any of this.

[CMdeux]

It's population correlation, of course--

and I have NO doubt that increasing exposure means increasing opportunity for contact among predisposed members of the population... but it looks (to me) as though increasing exposure through cultural dietary practices is what causes the frequency to reach some kind of saturation point.

It's both children and adults, though I'm not aware of data that pulls that one out specifically.  Just broad population data in incidence studies done in Scandinavia and the Middle East, as well as in SE Asia.

That seems to be what is happening in North America with sesame currently-- that it is attaining a level of ubiquity that means that everyone who will become allergic to it is becoming allergic.  The latency is being realized because of exposure, I mean.  I'm not sure that it supports the idea of "eating the allergen to prevent sensitization to it."

When you look at things that have always been ubiquitous in the diet in North America, though, like wheat, milk, egg, and to some extent some tree nuts like almond or walnut, the rates seem more stable and lower in incidence.

It'd be fascinating to look at rates in coastal versus inland areas and rates of fish consumption. 

In any event, consumption doesn't seem to actually be protective.  At least-- not anymore.  Whatever is causing additional food sensitization isn't playing favorites, it seems, and like everything else, the common wisdom that was perfectly valid for 40+ years about food allergy management doesn't necessarily apply to anyone now. Least of all to those born in the last 20 years.


I agree with the earlier observation that such advice is probably based on understanding of food immunotherapy methodology, and it may not even apply to those without the propensity to develop food allergy... of course, then that begs the question "is that this PARTICULAR child?"  The bottom line is that probably nobody knows-- the possibility probably exists if a genetic sibling already HAS developed food allergy, but beyond that,  it's anyone's guess as to whether it matters or not.

In any case, unless there are OTHER reasons to bring the allergen into the home, I would not necessarily call the evidence for "preventing allergy" to be compelling.  In the least.
 

[CMdeux]

Think about it this way--

IF this were true, peanut allergy rates should be falling as the North American food supply becomes ever more cross-contaminated with the stuff. 

Right?

But it hasn't. 

[twinturbo]

The other big reveal, which has actually been a huge pink elephant in the room the entire time, is that much of the data used in allergic disease has only been correlative because the statistical analysis has not been sophisticated enough to support causal relationships. The mathematicians here can explain it better than myself but to begin to statistically propose causality SEM (structural equation modeling) is required whereas what has been in use is only general linear regression.

In other words no matter how sophisticated the studies have been the math has been primitive, relatively speaking. I'm not saying DH & I are changing the world but we have pestered at least one large circulation allergy journal editor about moving towards SEM in order to study causal relationships. Yeah, when I first heard about that I needed my teddy bear and someone to hold me.

editing to add re: dust mite sensitization for the purposes of climate and regional populations Australia was included in an Australasia geographic boundary. I think what's interesting there is it's a population that has similarities to similar, young immigrant population based protoculture nations like USA, Canada, NZ (sorta, Maori have greater presence than other indigenous people in terms of percentage of population), and with Asian nations.

[CMdeux]

Yeah-- and many such studies have such significant sampling methodology problems to begin with that gross correlation may turn out to be all that they are good for.

Country-sponsored birth cohort studies are the most useful here-- but those are quite rare, and almost never available in mixed-ethnicity nations.

[jschwab]

I think it's a fallacy to assume most shellfish allergy is adult-onset and therefore different from peanut (though there may be research suggesting such that I'm not aware of).  Personally, I know equal numbers of people with adult-onset peanut allergy as I do adult-onset shellfish allergy.  My kids and I are all childhood-onset shellfish allergy.

However, if it's true that shellfish allergy is statistically likely to be adult-onset, then that could suggest the possibility of sporadic exposure leading to sensitization since shellfish allergy isn't more prevalent in coastal regions or populations who consume higher than average quantities of shellfish.  I'd be curious to know if adult-onset shellfish allergy is caused by different protein sensitization (perhaps one in chitin) than the sensitizing protein(s) of childhood-onset shellfish allergy.

I was really just musing on how I would be thinking about it (and do think about my own kids), not trying to put forth and prove any definitive thesis. Most articles I have read say that shellfish allergy is extremely rare in young children and much more common in teens and adults. I have no idea if it's more prevalent where it is a staple or not. Adult onset shellfish allergy matches my experience in the world, too. I have never met a kid with shellfish allergy, but I know tons of adults. That does not contradict the idea that children AND adults frequently become allergic to other foods equally (like peanuts), just that shellfish seems to need ongoing sensitization to develop through ingestion. It seems rare to have a toddler who reacts on first ingestion of shellfish but not rare at all to have a toddler who reacts on first ingestion of peanuts which gives me the thought that maybe there are different pathways to sensitization. I don't really know at all but those are the kinds of things I consider when I think about whether to expose my kids to foods I am allergic to (they have no food allergies). I was really just saying how I developed my judgement on the subject given the general information available. I am no expert, just a mom trying to think through the same quandary. The only thing I really have done is try to minimize the dust because the suggested link between shellfish allergy and dust mite allergy. Just stabbing in the dark here, really  .

[CMdeux]

Oh, as are we all, really-- just opinions.    Conversation, that's all.  Things to muse upon.

[rebekahc]

Oh, as are we all, really-- just opinions.    Conversation, that's all.  Things to muse upon.

Interestingly enough, DD's shellfish allergy manifested early and behaves more like a severe peanut/egg/etc. allergy.  Her first exposure to shellfish was when she was 3 years old.  We were out to dinner and DH ordered shrimp.  DD was sitting next to him and ate two french fries from his plate (from the side of the plate furthest from the shrimp) which resulted in hives and vomiting.  When she was 4, she put two fingers in the touch tank at the aquarium and reacted with full-body hives.  At age 6 we attempted the ocean - after about 45 minutes the first hives started to pop up.  Grocery shopping, she gets blotchy and wheezy when we're near the seafood counter.  That's why I was wondering if different proteins might be involved with adult-onset (exposure sensitization) and childhood-onset presentations like DD.

[twinturbo]

Oh, rebekah that's an interesting thought. It never occurred to me to think about pediatric-adult sensitization to different proteins or parts thereof.

[jschwab]

Oh, as are we all, really-- just opinions.    Conversation, that's all.  Things to muse upon.

Interestingly enough, DD's shellfish allergy manifested early and behaves more like a severe peanut/egg/etc. allergy.  Her first exposure to shellfish was when she was 3 years old.  We were out to dinner and DH ordered shrimp.  DD was sitting next to him and ate two french fries from his plate (from the side of the plate furthest from the shrimp) which resulted in hives and vomiting.  When she was 4, she put two fingers in the touch tank at the aquarium and reacted with full-body hives.  At age 6 we attempted the ocean - after about 45 minutes the first hives started to pop up.  Grocery shopping, she gets blotchy and wheezy when we're near the seafood counter.  That's why I was wondering if different proteins might be involved with adult-onset (exposure sensitization) and childhood-onset presentations like DD.

That is really interesting and I wonder? I find my own shellfish allergy extremely fascinating because I share it with my mother. As a kid, I'd assumed she was always allergic since she was a kid but it turns out we developed it at about the same age. Hers is mild, though, and she never ate shellfish growing when given the choice. I ate it all the time and my allergy is much more severe. Who knows? I mean, the people who get paid to figure it out haven't figured it out, so....