My brother is allergic to raw carrots but has no reaction to cooked ones. How is this possible?

-- asks Tony from New York, NY.

If the spinach doesn't get you, the carrots might. [CREDIT: USDA]
By | Posted October 15, 2006
Posted in: Ever Wondered?, Life Science
Tags: , ,

The humble carrot, familiar fare for Bugs Bunny and armies of school children, can be a dangerous, even lethal, snack for a small number of people. Heating the carrot, however, can render them harmless to the allergic, according to a recent study.

But how could a little heat turn a vegetable from deadly to delectable? And how can a wholesome carrot be dangerous in the first place?

The carrots we buy in grocery stores are certainly not poisonous. The carrot, native to Afghanistan, is a root that has been grown and eaten for thousands of years. The typical orange variety was developed in 17th century Holland. Carrots are a good source of carotene, the compound that our bodies convert into Vitamin A.

This innocuous, nutritious vegetable is nonetheless dangerous to those people whose bodies react to it as a foreign invader. These people have immune systems that respond to carrots in ways that are usually reserved for illness-causing germs. No one really knows why this happens, but food allergies are becoming more common and seem to be on the rise in the industrialized world.

The cause of this proliferation may be excessive cleanliness. Today’s western children are exposed to fewer microbes not only because of the lack of dirt and germs in the foods they eat, but because they are more socially isolated than children in developing nations. Research has shown that children who attend daycare have fewer allergies than children who remain at home. Furthermore, both children and adults use antibiotics to combat microbes in their environments. In sterile environments, immune systems lack enemies, and may attack food proteins as if they were germs.

Our bodies are protected from germs by the antibodies that constantly roam the blood system looking for foreign invaders. For allergic people, antibodies target food proteins moonlighting as allergens. When antibodies detect an allergen, a reaction occurs. The body’s response to an allergen can cause a variety of symptoms from facial swelling to serious anaphylactic shock. In carrots, several proteins can cause a reaction.

Everyone knows that cooking carrots renders them mushy. A little heat breaks down the carrot’s cell walls, and turns this crunchy vegetable into perfect baby food. Heat, in fact, makes many vegetables more palatable. In their natural state, plants have ways to avoid being eaten. These defense mechanisms are called secondary compounds and can be poisonous to the eater. Most common crop plants have long since lost these harmful effects, and cooking some toxic wild plants can break down their toxins, making them edible.

When carrots are cooked, the potentially allergenic proteins within them unravel, rendering them safe from targeting by the immune system. According to a recent study in The Journal of Allergy and Clinical Immunology, these denatured carrot proteins can no longer bind to the posse of antibody scouts, and when antibodies cannot recognize allergens, a strong immune response does not occur. The same study found that cooked carrot protein can still activate a milder immune response that causes a less dangerous reaction. Some participants who ate cooked carrots did not swell up and suffer breathing problems, but did get rashes from the second type of immune response. Because of this, researchers recommended that people allergic to carrots avoid carrots in all forms, even though heating reduces risk.

Don’t run to the crisper and dump those carrots just yet, though. Not many people have bonafide food allergies. The FDA estimates that only about 1.5 percent of adults and six percent of children have some kind of food allergy. Children outgrow most allergies, and allergic adults are typically only allergic to a few foods. Allergies to carrots are most common in Europe, where up to 25 percent of people with a food allergy need to avoid this orange root. Some experts say that food allergies develop in adults because of previous sensitivity to pollen; the patient may become allergic to a variety of plants that contain proteins similar to those found in the pollen. For example, celery, which is related to carrots, mugwort, certain spices and birch pollen all contain the same allergenic carrot proteins that some people just can’t stomach.

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  1. My son has had Oral Allergy Syndrome to carrots, celery , apples for a few yrs. He would complain of an “itchy” throat and at times I thought I noticed white papules on his posterior tongue after such fruits or veggies even in small quantities. Pediatrician said to just avoid–not a dangerous allergy and so we did. About a month ago he got an incidental carrot from a salad ( usually we made his salad separate but one snuck in) and within a few minutes he had a voice change and complaint of difficulty swallowing. I immediately gave Benadryl and was getting ready to go to Urgent care when he got better quickly. We were referred to allergist who confirmed he indeed had 4+reaction to celery and carrots and oral allergy syndrome to apples. She prescribed epipen and recommended avoidance…even for cooked. Cooked apples fine. He also has an allergy to several tree pollens, including birch. Just a note of caution if you think it’s just an “oral allergy syndrome” “not the dangerous kind” you may want to have it really evaluated by an allergist with testing to be sure. We were shocked!

    Kim, August 8, 2013 at 9:34 pm
  2. My 9 year old daughter is allergic to raw and cooked carrots, so this makes shopping trips hectic and unless I know she has already ate a product then I have to read every single label and I have to train everyone who cares for her how to administer an epi-pen and I have to watch dates on the epi pen… I would hate to use an epi -pen because she would be very sick

    Jennifer Gregg, December 5, 2013 at 10:37 pm
  3. Soy milk caused me yo rush to the ER…in the waiting room my girlfriend gave me a Zirtec, and i was fine. Throat was swelling and closing fast….. Today, snap peas did it to me. zirtec solved the pronlem. I also get a puns and needles feeling from carrot juice.

    Mike, March 30, 2014 at 9:20 pm
  4. Glad I found this article. I’ve had a carrot allergy for years, and my son has hd oral allergy syndrome to apples (ER didn’t believe me that was why his mouth swelled). Anyone else get a rash to carrots as well? If I eat something with carrots in it by mistake, I get a very itchy rash that lasts up to 6 weeks in small areas of my body.

    Sue, April 12, 2014 at 2:55 pm
  5. Wow. Am I glad I found this. F I developed this when I was about 7 ny mum didn’t believe me so she made me a glass of carrot juice from the juicer…my reaction was not life threatening but it was borderlining. Severe itchiness in throat ears mouth ingeneral and almost complete swelling of the throat. Since then I never ate raw carrot. Cooked no problem. My wife still does not believe me even trying to make me take a bite to prove that it is “all in my head”. That’s when I done the search and came across this. Thankfully :)

    Since that day, over the course of my life I have developed intolerances to other foods. None life threatening but all with same symptoms. Itchiness of mouth, throat, pulsating of gums and itchy ear canal. These include hazelnuts, almonds, wallnuts, cherries, kiwi, strawberries, apple’s, pomegranates. All with different levels of reaction and all quite fine when cooked. Amazingly I am perfectly fine with peanuts, although my son is anaphylactic to them. Ironic. I do have hayfever for the record. It seems to be a common link in all of us.

    adnan, June 28, 2014 at 6:56 am
  6. When ever I peel carrott I get asthma attack. I have to puff the inhaler right away. I thought may be the fertiizer is the issue so I tried with organic carrott same thing happened. When I peel potato it is very mild however with carrott it definitely gives me asthma. Wheezing problem. I have noticed this for a while. I can eat carrott with no problem. Peeling is the problem. Why is that?

    Ro, November 25, 2014 at 1:22 pm
  7. I am very allergic to carrot. Only to raw carrot. I can eat cooked carrot.

    Gina, November 26, 2014 at 2:32 pm
  8. After read almost all the messages make me happy ( in some how ) found that I am not the only one,
    Same as Adnan, my Mom don’t believe me she use to make me a glass of carrot juice, every time when I drink it was getting worst, now I am in this point that I can’t even eat or drink anything if was in contact with Raw carrots, that juts close my throat :( I need to have an epipen with me, just in case … Also happens if I eat a lot celery raw.
    I was big fan of eat salads in the restaurants, but now I don’t like to take a chance, normally they are not sure if the use the same knife .

    Any way it’s my way to living now, I just eat salads at home or with really close friends how are aware of my allergy.

    Sonia, December 19, 2014 at 12:26 am
  9. I had a carrot juice drink in a restaurant last night, and had a terrible reaction (sneezing, itching, face on fire, eyes swollen, lips swollen, hives, and mild breathing difficulties). I took anti allergy pill and a few hours later a decongestant (my sinuses were really painful).

    I’ve never noticed having an allergy to raw carrots, but I wonder if the restaurant prepares the raw ingredients the night before – and I’m suffering the reaction that poster #5 refers to?

    Andrew Smith, January 5, 2015 at 5:11 am
  10. So I have had a banana allergy since I was about 5 (very allergic), and following that I have developed allergies to peas, and then apples, and raw tomatoes. In recent years it seems I have had allergic reactions to more and more fruits and vegetables, particularily when they are raw. Some of these include oranges, clementines, occasional raspberries, strawberries, roast beef, and others I that are hard to keep track of. it gets exhausting to keep adding foods to this list as I really enjoy fruits but i cannot seem to figure out what is causing these allergies.

    One interesting note, is that I studied abroad (I am 22) in Italy last year, and had access to a fresh produce market in town where most of the fruits and vegetables were grown locally in Italy (I suspect without GMOs), and I figured I would try a shot at eating some of the things I am less allergic to. In particular, tomatoes and oranges… Before I was unable to ever eat these raw, but I tried the italian ones and I had no reaction, boom. Then a couple of months pass and tomatoes are no longer in season so they begin importing them from other places, and I start to have reactions.

    Don’t know if anybody else has these common allergies and know what might link them? I wonder also if it could be the preservatives used to prepare them for shipping?

    Nic, January 22, 2015 at 11:57 am
  11. While I also have the throat and voice reaction to carrots cooked and raw as well as celery. I have to use an albuterol and QVar inhaler to stop coughing and there may be many more that precipitate hoarseness I was wondering if any of you know about nightshade arthritis? Night shades are tomatoes, any kind of peppers (except black), eggplant, tobacco, and sadly white potatoes. Those of you who have this will hurt all over. Think you have arthritis or fibromyalgia. Try eating Mexican or Italian food and then use some Italian dressing (the kind with little bits of carrot :) ). If you find yourself in excruciating pain all over for several days you may want to Google Nightshade Arthritis.
    Also Mel Blanc the voice of Bugs Bunny was severely allergic to carrots! And rye bread I would imagine.

    Diane, February 18, 2015 at 11:03 pm
  12. I have been allergic to raw carrots and celery since childhood. I am 49 now. I’m also DEATH allergic to nuts from trees including coconut. I’m allergic to fish but NOT allergic to shellfish or mollusks. Finally I’m allergic to black Eyed Peas and cantalope, tomatoes, bananas and watermellon. There is no cure for my allergies which saddens me. I would love to try pecan pie or Salmon.

    Randall Bland, April 10, 2015 at 9:01 pm
  13. I’m not alone in there! How nice that is.

    I have several allergies (including raw carrots while I have no problem with cooked carrots).

    I used to have a mild reaction to cantaloupe and to some nuts (especially when eating raw). I used to have a reaction to apricots and celery as well but not anymore apparently.

    I am really curious to know how it is possible for allergies to come and go.

    I probably did something right by desensitizing myself for some of them.

    I am still however avoiding raw carrots like the pleague as even simply peeling them gives me a skin reactions.

    my name is required, April 17, 2015 at 5:58 pm
  14. After my allergic reaction I went to an allergy clinic in London (UK) and as part of the session, was given a sheet of notes with the following information:

    Birch Oral Allergy

    Birch oral allergy is when the body mistakes proteins in foods for the birch pollen protein. This commonly causes an itchy mouth, and sometimes a swollen tongue after eating certain fruits, vegetables and nuts. Most individuals will also get hayfever symptoms in May and April (the birch pollen season). Usually these symptoms are not serious and are very unlikely to cause dangerous allergic reactions.

    Common foods which may cause symptoms:
    Apple, Peach, Pear, Nectarine, Carrot, Potato, Fennel, Spinach, Walnut, Peanuts, Cherries, Plum, Honey

    Other pollens which may cause food related symptoms:

    Mugwort – Celergy, Spices, Watermelon, Camomile tea, Carrot, Melon, Apple

    Grasses – Melon, Watermelon, Tomato, Wheat, Swiss Chard

    Ragweed (uncommon in UK) – Melon, Honey, Sunflower seeds, Camomile tea, Bananas

    Pine – pine nuts

    Hazel – Hazelnuts, Cobnuts

    Pellitory – Cherry, Melon

    Some people who react to raw fruits and vegetables find that they can tolerate them cooked.

    Andrew Smith, June 11, 2015 at 7:40 am
  15. Hi all –
    Really great to find this article and especially the comments from everyone.
    I too have an allergy to raw carrots but not cooked ones!
    It’s kind of reassuring to know that I’m not alone!
    I’m not someone who is typically sensitive to things but sometimes raw carrots just seem to get me. Typical symptoms include heartburn and a severe indigestion feeling, almost like a mild cardiac arrest! Choking and difficulty breathing.
    Wierd huh.
    Interested to hear from others who get the same.
    Cheers guys :-)

    David, June 19, 2015 at 2:23 pm
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    Titlovani filmovi, June 20, 2015 at 4:18 pm
  17. I too was so happy to read this, finally I can tell my family and friends I’m not just a picky eater, there was a reason I didn’t like eating certain foods. My list is growing every year but atleast I got to eat these foods up until my late teens when I first developed seasonal spring allegies, only when the trees start to bud do I get the itchy eyes, scratchy throat and sneezing. Carrots like many was the first to get me thinking, I too got the itchy mouth/lips sore throat and then extremely paralyzing pains in my back and chest area. Then one night I was cracking open hazelnuts, I think around the forth one I ate I started to get the itchy throat, so I stopped, within 2-3 minutes I could barely breath, I layed on my couch with my head tilted back just to breath, after 20-25 minutes the throat swelling went down and I only had the severe back pain. Needless to say this was the start of my new strict diet. My list so far: Carrots, Almonds, Peanuts, Hazlenuts, Apples, Watemelon, Bananas, Celery, Cherries, Romane lettuce, Green grapes, Oranges..Age 37 now, Thank you so much for this site..Keith

    Keith Black, August 18, 2015 at 12:16 pm
  18. Thank you for this article and these comments. I am also allergic to raw carrots. Additionally, I am allergic to raw apples, raw peaches, raw celery, raw mangos, raw kiwi, raw bean sprouts, and who knows what else. I can, however, eat peach cobbler all day and carrot soufflé (Picadilly style). I didn’t develop these allergies until the 4th grade. Apples are my favorite fruit. Really the only thing I can eat raw, safely, is lettuce, cucumbers, tomatoes, bananas (which I hate) and grapes. I’ve had a mild reaction to too many strawberries. I might be ok with blueberries, but don’t like those much. Enough about me… Thanks again! Oh and I have never been clinically diagnosed.

    NiecyJ, December 19, 2015 at 9:39 pm
  19. I also have a severe allergy to raw carrots, celery, potatoes, and more. I have noticed that the older the fruit or vegetable is, the more ripe it is, the worse my reaction tends to be.
    I keep liquid Benadryl on hand for times I accidentally come in contact with these fruits and veggies. Has anyone noticed their allergy is worse the riper the food?

    Trish, January 11, 2016 at 3:46 pm
  20. I love the taste of raw carrots, hate the taste of cooked carrots, not allergic to either and this has nothing to do with texture. Obviously there’s some biochemistry involved when carrots are cooked that results in a very different flavor. Hope some entity scientifically studies this and can supply a detailed definitive answer as to cause – also the percentage of people that hate cooked carrots. This has ramifications for companies that specialize in processed foods (e.g., beef stew, chicken soup, etc.).

    emansnas, April 4, 2016 at 3:58 pm
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