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Lectin Cross Reactivity and Oral Allergy Syndrome

Answered on August 19, 2014
Created July 29, 2010 at 4:07 AM

Since childhood, I knew that if I ate raw apples, my throat would shortly itch like crazy. I was allergic, although luckily not life threateningly so, but didn't why it only happened with raw apples, not cooked. I guessed that cooking must somehow alter the element that was causing the allergic reaction. But it was only today that I discovered the allergenic culprit. It was... dum dum dum dum... LECTINS! Yup, looks like fruit has some of those darned lectins too, although apparently they are usually significantly denatured by cooking.

And the itching and coughing I experience is apparently called oral allergy syndrome.

And why do I get this? Apparently it stems from an allergy to some lectins in, of all things, pollen! Friggin lectins are taking over the Earth it seems! Looks like if you develop an allergy to a pollen that happens to have a lectin very similar to a lectin in some fruits, then you may develop an immune reaction to the fruit as well. In my case, raw apple allergies are associated with birch tree allergies. I don't know if I am allergic to birch but it may be no coincidence that hoards of birch trees lined the street I lived on when I was growing up. This kind of cross over allergic response is called cross reactivity or cross reaction. CHeck out the wiki: http://en.wikipedia.org/wiki/Oral_allergy_syndrome

Any one else have oral allergy syndrome or cross reactivity with a pollen allergy?
(scroll down on the wiki for a list of cross reactive pollens/fruits)

D31a2a2d43191b15ca4a1c7ec7d03038

(4134)

on October 30, 2010
at 01:24 PM

http://failsafediet.wordpress.com/ is now the website, which used to be plantspoisonsandrottenstuff.

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on August 02, 2010
at 05:48 AM

It's possible but seems unlikely. They are saying salicylates decrease with ripeness, but my allergy increases with ripeness. Plus many other items on that last have far more salicylates but I have no reaction to them.

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on July 30, 2010
at 04:10 AM

True enough, you did say 'unlikely.' I should read more carefully.

0bc6cbb653cdc5e82400f6da920f11eb

(19245)

on July 29, 2010
at 05:10 PM

That is true, I said "unlikely" :) I think serious reactions are pretty rare out of all the people with this type of allergy. Compared to peanut allergy for example.

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on July 29, 2010
at 04:13 PM

Realized I didn't answer your question. Looks like lectins (lectins are just proteins really) are present in all fruit but you are only likely to react allergenically if the lectins in a particular fruit are very similar to pollen lectins that you are also allergic to. So what fruits you react to are determined by what pollens you are allergic to and what fruits have similar enough lectins to those pollens. And probably also have much your immune system tends to extrapolate between similar allergins.

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on July 29, 2010
at 04:10 PM

I have noticed huge differences in response to different apples at diff times of maturation. Unripe ones seem to give much less response. And even the ripe ones vary. My guess has long been different levels of the allergenic substance are present in diff apples. But I guess it could also be partially a different reactivity in me each time? Can't tell for sure, but my money is on the main difference being in the apples themselves. Apples are my main trigger, although some other fruit also do it. However, other things on the list with apples don't seem to trigger me.

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on July 29, 2010
at 04:06 PM

For some, the throat can swell closed and kill you or you can go into anaphalactic shock. That's a bit serious! They also said that digestion only stops it for some. For others, small amounts of undigested protein carry the allergic reaction all the way into the intestines.

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5 Answers

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2
A68f24168bc0de414a038037e287b581

on July 29, 2010
at 01:02 PM

Well, now I understand more the link :) I do have pollen allergy (trees, not grasses), and I do have some fruit allergies. Probably only the oral syndrome, the itching around the tongue and so on... Funny thing is, it comes and goes. Sometimes I can eat apples without problem, sometimes it causes stronger reaction. After eating a pear I not only had horrible stomach ache but also had some swelling around the eyes, so I don't even try to come close to pears anymore. Almonds and to lesser effect some other nuts, cause bad stomach ache without any itching... So weird.

I remember the doctor telling me that the oral allergy syndrome is not "real" allergy and I have nothing to worry about, but still... I eat less fruits now anyway, so less issues.

Are lectins present in all fruit? Does it have different levels and that's what determines if you are allergic to them?

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on July 29, 2010
at 04:13 PM

Realized I didn't answer your question. Looks like lectins (lectins are just proteins really) are present in all fruit but you are only likely to react allergenically if the lectins in a particular fruit are very similar to pollen lectins that you are also allergic to. So what fruits you react to are determined by what pollens you are allergic to and what fruits have similar enough lectins to those pollens. And probably also have much your immune system tends to extrapolate between similar allergins.

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on July 29, 2010
at 04:10 PM

I have noticed huge differences in response to different apples at diff times of maturation. Unripe ones seem to give much less response. And even the ripe ones vary. My guess has long been different levels of the allergenic substance are present in diff apples. But I guess it could also be partially a different reactivity in me each time? Can't tell for sure, but my money is on the main difference being in the apples themselves. Apples are my main trigger, although some other fruit also do it. However, other things on the list with apples don't seem to trigger me.

1
E625bf07d49dc5eeda5c1ca2116b9cc4

on October 06, 2010
at 05:46 PM

Obviously, there is a lot of information available. Here's just one site: http://www.calgaryallergy.ca/Articles/English/Oral_Food_Allergy.htm

Although I had allergies as a kid, I didn't start having problems with food until my 30's. The first to hit me was the apple. Throat starts to narrow after a few bites, although I can still handle apple sauce, and apple pie. Today there are a few that give me problems to various degree. I'm debating on getting allergy shots. My regular allergies don't both my a whole lot, and they say shots don't help everyone with oral allergy syndrome, and if they do help, they just lessen the problem, not eliminate it.

Anyone gone the allergy shot route?

1
0bc6cbb653cdc5e82400f6da920f11eb

(19245)

on July 29, 2010
at 02:19 PM

Chill out about the lectins. They are simply proteins that specifically bind to a certain type of sugar, usually the sugar is part of another protein, without altering the sugar they bind to. Lectins are everywhere in nature because they are involved in many different biological functions. Lectins are found in plants, animals, bacteria and viruses.

Your own body contains lectins including the Mannose binding lectin that plays a vital role in your immune system. The only ones you need worry about eating are lectins that cause harm, usually by binding to cells in you gut wall and that also resist digestion.

Oral Allergy Syndrome is a fascinating example of how they immune system works. It is also one reason that the common types of allergies are vary in different parts of the world. You would be unlikely to become allergic to apple on its own as the protein antigen is digested and would not encounter any immune system cells. This is why you only experience the reaction in your throat. Cooking also denatures the protein. However the birch pollen protein can reach immune cells deep in your lungs where your immune system learns to recognise the pollen protein as foreign as this results in IgE antibodies being produced.

It is a real allergy, however it is unlikely to produce a serious allergic reaction due to the protein being quickly digested.

0bc6cbb653cdc5e82400f6da920f11eb

(19245)

on July 29, 2010
at 05:10 PM

That is true, I said "unlikely" :) I think serious reactions are pretty rare out of all the people with this type of allergy. Compared to peanut allergy for example.

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on July 29, 2010
at 04:06 PM

For some, the throat can swell closed and kill you or you can go into anaphalactic shock. That's a bit serious! They also said that digestion only stops it for some. For others, small amounts of undigested protein carry the allergic reaction all the way into the intestines.

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on July 30, 2010
at 04:10 AM

True enough, you did say 'unlikely.' I should read more carefully.

0
3864f9a2af09b1b447c7963058650a34

(3703)

on August 02, 2010
at 05:27 AM

Eva,

Perhaps you are allergic or sensitive to salicylates which are often found in apples and apple products (even including many nutraceuticals)...?

http://www.plantpoisonsandrottenstuff.info/content/elimination-diet/salicylates.aspx

-G

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on August 02, 2010
at 05:48 AM

It's possible but seems unlikely. They are saying salicylates decrease with ripeness, but my allergy increases with ripeness. Plus many other items on that last have far more salicylates but I have no reaction to them.

D31a2a2d43191b15ca4a1c7ec7d03038

(4134)

on October 30, 2010
at 01:24 PM

http://failsafediet.wordpress.com/ is now the website, which used to be plantspoisonsandrottenstuff.

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