What causes food allergies?

Factual Questions
1

I was set to thinking by this thread in the Great Debates forum.

About 7 years ago, when I was about 19 or 20, I discovered that I was allergic to shrimp. This surprised me, for I had eaten shrimp a number of times as a kid with no ill effects. It wasn’t my most favorite seafood, but neither did I turn it away.

The intensity of my allergy to shrimp is amazing. If I accidently swallow any part of a shrimp, I can actually feel the reaction occurring in my throat as it makes its way to the stomach. The last time I had any shrimp was on Christmas Eve, 1999, when I accidently consumed one of those little itty bitty baby shrimps that was buried underneath some dressing in a salad. Just one of those little things, only the size of a lima bean, made me so ill that I couldn’t eat dinner, and I was laying on the couch reeling for the remainder of the evening until well past midnight. My throat actually ached.

I shudder to think what could happen if I deliberately consumed a larger specimen of shrimp, or even more than one of them.

My question is, if I wasn’t born with this allergy, why did I develop it? What conditions caused me to become so intensely allergic?

And does being allergic to shrimp mean that I’m allergic to all other varieties of shellfish. I have avoided eating crab, lobster, etc. just to be on the safe side, but I have no way of knowing if this is excessive prevention.

2

It’s basically caused by a misfiring of your immune system. If you get a screwy B or T cell that reacts to an antigen in the food, it can cause a delayed-type hypersensitivity reaction, aka an allergy. Someone will probably be along shortly with a more detailed explanation, should you so desire. I’d have to dig out my Immunology textbook to go deeper. It’s been a while.

3

Before this thread gets rolling too far, I’d like to pose an additional question to the one the OP asked: why does it seem that children these days are more likely to develop food allergies? Are we just more aware of allergies these days, or is it a difference in how kids are being raised, or the content of the food they eat, or what? Anyone know?

4

I was surprised to learn that I’m allergic to MANY of my favorite foods, albeit slightly. I’m slightly allergic to milk and dogs, yet I drink 2 glasses of milk every day and I have a dog. I wonder if this is bad for me? Hmmm.

5

One factor may be the trend of encouraging parents to add solids to their infants diets very early. For a while there, it seemed like kids were barely out of the womb before someone was trying to stuff cereal into their mouths. There is a very strong correlation with early exposure to foods and allergies. There are some foods (strawberries and egg whites are two) that known to cause problems more often, and we are warned against them, but any food can cause allergies if infants aren’t ready to digest it. Add to that the increased variety of foodstuffs available to us and you may have part of the answer.

Parents with a family history of food allergies are often encouraged to stick to breastmilk (or formula) only for a full year to give the infant’s digestive system time to develop fully.

6

It is also possible to sensitize to something (either food or drug) over a long period. I didn’t find out I was allergic to penicillin (which I know isn’t a food unless eaten in its raw state, on bread) until I was in my twenties. I was prescribed penicillin, took one or two doses, and broke out in a severe case of hives that took steroids and Benadryl for a week to get rid of.

Robin

7

I am deathly allergic to peanuts. I have reactions when I eat other nuts, but not nearly as bad as peanuts. A few weeks ago I ate some split pea soup and ended up in the hospital. I can’t eat any good candy bars because they all contain nuts and if they don’t contain nuts they have a warning that they were “made in a facility that uses nuts”. A few years back a girl died from eating chili that had peanut butter as the secret ingredient. I hope I grow out of it, but for now I will just have to continue living my life in fear :slight_smile:

8

A misfiring of the immune system, eh?

That makes me wonder about something else. Does the fact that I developed this allergy to shrimp (and possibly all other shellfish) meant that I’m more prone to develop other kind of food allergies as well?

I hope not. Because of the shrimp allergy, I have to be careful about what kind of sushi I order. I would hate to have to add other kinds of foods to that list.

9

I too am extremely allergic to peanuts. Peanuts are legumes, rather than true nuts (tree nuts), and I’m actually allergic to all legumes to some extent. horhay_achoa, sounds like you’re in the same boat. I believe peas are legumes as well. I’ve always had a reaction to peas, but a mild one compared to peanuts.
My sensitivity to peanuts has lessened over the years, but there are still a lot of things I have to avoid. Thankfully, the general public has become much more aware of this allergy! You wouldn’t believe the reactions I used to get when I would tell people. . .
I have the same experience as the OP when I eat anything with peanuts. My whole mouth burns the instant I get even the slightest taste. I also literally cannot stand the smell of peanuts or peanut related products. The very smell makes me feel ill. My theory about this is that it is a self-defense mechanism that my body has developed to help protect itself against peanut contamination. My aversion to peanuts is so strong that I can’t really even imagine them as a food. I’m curious if anyone else has this kind of experience with a food they are severely allergic to?

10

Enigma42 - Regarding the aversion to allergens thing, my son has that. He had (up until he turned about three) a majorly nasty allergic reaction to eggs - he’d develop a bright red rash on contact. Now, he didn’t have eggs at all until he was about 18 months old, and then only yolks (I was avoiding the allergenic whites…) unfortunately, he reacted to yolk, too.

He’d always disliked certain foods, and the egg thing didn’t click until later… he dislikes most cookies, cake (but loves frosting and other sweets), egg noodles, etc. Initially, when his reaction was most severe, he’d immediately dig the offending food out of his mouth - with both hands, if necessary! Now, he avoids anything that smells of eggs, and he ‘tests’ food by touching it with his fingers (since he’d get a reaction anywhere, fingers were safer than mouth). Also, he’s taken to telling people that he’s allergic to any food he doesn’t like … basically, because he didn’t like any foods he was allergic to, he assumed any foods he didn’t like (regardless of reason), he was also allergic to. Good reasoning for a 3-yr-old. Still doesn’t like cake, and the egg allergy seems to have faded in the way some early childhood allergies do. Cake just isn’t a food, for him. He won’t try pancakes, either, so far, despite the allergy being fairly well gone from what we can tell (he’s almost 4).

Also, technically, if you aren’t ‘seriously’ allergic to something, it qualifies as a sensitivity, not an allergy. Allergy gives you a reaction to any quantity of the item, sensitivity gives you a degree of reaction above a threshold of exposure, relative to the degree of exposure. When I had my allergy testing done, I got huge welts for a bunch of things (trees, molds, pollens) and a small welt for cat dander. I said, oh, I’m allergic to cats, huh? And the allergist said, no, you aren’t - you are just SENSITIVE to cats. Big difference in risk from the reaction - allergies can be life threatening on minimal exposure, sensitivities are seldom life-threatening, but often annoying. You can manage a sensitivity by keeping your exposure down, but you have to completely avoid true allergens to avoid a full-blown reaction.

Atreyu, usually if you are allergic to one kind of shellfish, you are allergic to all of them. They share a protein that is generally the source of the reaction. Sorry!

11

Unfortunately, yes.

I’ve had multiple food allergies since childhood. Every ten years or so another item gets added to the list. If I live to be a 120 I’ll wind up starving to death because I’ll be allergic to everything.

12

I hope you mean you have a pet dog and not that dog is one of your favorite foods. :slight_smile:

I read that too fast the first time and thought it was cute.

13

Before I forget…

ANYONE who is allergic to shellfish needs to have this entered into their medical records. It is extremely common for these patients to react to x-ray contrast that contains iodine (such as for CTs).

Robin

14

Shoot. No one’s shown up yet with a medical explanation? I guess I’ll have to dig up my textbook when I get home tonight. If I remember.

Atreyu - I don’t believe that having one allergy increases the chance of getting others, but I don’t know for sure.

15

From reading the responses, it sounds like:

  1. I’m allergic to other shellfish, just as I suspected.

  2. I may be more prone to developing other food allergies. Great. If I ever become allergic to chocolate, somebody please kill me.

  3. I should always inform doctors of this allergy, since certain kinds of X-Ray tests could mess me up.

Does #3 mean that there are certain kinds of medications that I should avoid? Perhaps I should add “pharmacist” to the list of people to inform about this allergy.

16

The big thing about an allergy to shellfish is that they contain iodine (Sp check – its early and I’m going to bed soon) Any invasive procedure usually requires the area to be cleaned with iodine first, and some x-ray tests contain iodine.

17

Whenever I get the “do you have an allergies” question from a medical person I mention the food allergies, because you never know where a particular medicine or substances might have come from. There are vaccines cultured in eggs, snake anti-venom derieved from horse blood, various products developed from cow and pig parts, I seem to recall some sort of medical test using the blood of horseshoe crabs, antibiotics that set off mold allergies, and so on. Also, just knowing that you have any allergies should alert the medical people that your system is prone to that sort of reaction so (hopefully) they’ll be keeping a close watch on you and treat aggressively any problems that arise.

Of course, there ARE dimwits in the medical field who just don’t give a damn. I could tell you horror stories, but just don’t feel like going through the trouble this morning.

18

OK, here goes. I’m home and I have my Immunology textbook on my lap.

Food allergies are classified as Type I hypersensitivity reactions. Basically, one of your B cells, which are the cells that make antibodies, reacts to something in the food and starts making antibodies. What’s unusual is that they make a type of antibody knows as IgE. IgE antibodies have good, normal roles in life, but they’re inappropriately expressed in allergies. IgE molecules are able to bind to the surfaces of mast cells and basophils. They bind in unusually high concentrations. Then upon a second exposure to the allergen, the bound IgEs crosslink, causing the mast cells to release their contents. Since mast cells are basically the immunologic equivalent of nuclear arsenals, you then feel like crap.

All of that applies to allergies in general. With food allergies, the above reaction takes place on the surface of the gastrointestical tract. When the mast cells go nuts there, it can induce nausea and vomiting. Interestingly, it also increases the permeability of your gut lining, which can allow the allergen to enter the bloodstream, leading to a more generalized and potentially more serious reaction.

19

This is a very interesting question especially to folk like me.

When I was very little about 2 I developed allergies to Milk and had to have soy milk. Then about a year later it went away. When I turned 9 years old all of a sudden it came back. I would get huge hives (utecaria Sp??). And then when I drank any kind of orange pop I would get them. A year later it went away.

When I turned 16 they came back again worse than ever, six months later it disapeared again.

When I turned 22 it was awful again. My whole stomach and chest was one big hive I have never seen it so bad and my doctor said he’d never seen a body that was basically one big hive. Boom six months later they went away.

When I turned 27 I got sick and thought I had bronchitis and it didn’t go away. Later they said I developed Asthma. Who gets asthma at 27. I can even tell you the exact day it started.

Then I moved to Florida and boom as soon as I got there the asthma got better but the hives came back in full force. I was tested at both Johns Hopkins and Mayo Clinc for these huge hives. All tests came back negative.

It was so bad my eyes would swell and I had black eyes. The doctors at Mayo asked if I had to live in Florida. They said since I live so close to the Everglades it could be anything. So I moved to Chicago. Boom allergies waned and in 6 months left me totally. Have been back since 94 and have no problems with hives.

So it appears in some people they can come and go at random.

For instance this summer my Asthma was so bad they put me on a week of steroids. But for the prior year I would use my inhaler maybe once a month if that.

And I had a bit of an infection so my doctor gave me penicillan and I had a mild reaction to that. I have taken penicillan my whole life and NEVER had trouble with in in any form.

So I can say from my point of view allergies can be very weird things.

20

Thank you, Smeghead, for taking the time to provide that information. I found it very interesting, and I appreciate your effort.

“Feel like crap” is an apt description of how I felt after having just that one tiny baby shrimp a couple of years ago.