Thursday, March 08, 2007

Are people with peanut allergies also allergic to peas, beans and other legumes?

Who's asking: Sally Gawne and Kathy Miller, Jacksonville, FL

It had never occurred to me to wonder about this, but once Sally and Kathy asked the question, it seemed obvious: wouldn't a peanut allergy mean that you couldn't eat peas and beans, too?

But no, as it turns out. Most people with peanut allergies can eat most types of legumes without having to worry about allergies. The peanut allergy is a sensitivity to one or more of three chemical compounds in peanuts. Two of those compounds occur only in peanuts; one of those compounds appears in soybeans as well, so some people who are allergic to peanuts can't tolerate soybeans, either.

The bigger question is why peanut allergies are so much more common now than they used to be. No one seems to know the answer to this. One theory is that since children no longer get many of the traditional childhood diseases, they don't build up resistance to various plant substances.

My own theory is that it's natural selection at work. We see more kids with peanut allergies and asthma these days because these kids now live normal lives, instead of dying young for unknown reasons or being kept at home as invalids. They grow up and have children of their own, who also have peanut allergies and asthma. In a weird way (in my opinion), they represent the triumph of medicine over biology, not that our environment's getting more toxic.


Steve D said...

What you call a "triumph of medicine over biology" I call the weakening of our species.
Don't get me wrong, I'm all for medicine and things to help us survive, but consider many of us would have survived even 2000 years ago much less pre-history without even simple things like glasses. I wouldn't have.

AnswerGirl said...

"Weakening" is the wrong word; natural selection's just shifted its focus from physical resilience to mental ingenuity.

Eventually we will all just be heads on wheels.

Claire said...

Steve has a theory that food allergies in general are more common because of the rise in imported foods. I pointed out that this holds for peanuts allergies in Canada--they don't grow here--but not in the US, where they've been a common crop for two hundred years. Still, it's an interesting point to consider; legumes aren't really indigenous to the Americas, and there's a marked lack of peanut/soy allergies in Asia.

Anonymous said...

There are some native Legumes such as Vetches and Marsh Peas. when you bring up marsh peas on the Lathyris palustris on the U Wiscons SP sight, a "harzard warning" pops up so maybe they are already allergenic (is that a word?


steve said...

I have read that Asian countries have a completely different way of processing peanuts. The North American process ultimately enhances the chemical or protien in peanuts that so many people are now responding to. I believe that the increase in peanut allergies is simply a result of changes in processing techniques.

You may already be aware that most food allergies are actually pollen allergies. If you have an allergic reaction to carrots, cherries, apples, pears, parsnips (a newly discovered allergy for me), hazelnuts, etc., what you actually have is a birch pollen allergy. Those allergic to ragweed may also find themselves sensitive to melons and bananas. A sensitivity to Mugwort may cause one to react to various spices. The cross-reaction occurs because the poteins in these foods are so similar to the pollens that the body can't tell the difference.

Almost all fruit and vegetable proteins are destroyed during the cooking process so most of these foods become harmless when cooked. This is certainly true in my case.


Gwen said...

To say that "most food allergies" are pollen-related is absolutely incorrect. What you describe is called Oral Allergy Syndrome in which a pollen-allergic person cross-reacts to fruits and vegetables (and often nuts) in the same plant family.

But this is NOT classic food allergy and people with OAS are not usually at risk of anaphylaxis, the life-threatening form of food allergic reaction. People who are allergic to one or more of the big allergens: peanuts, soy, tree nuts, milk, shellfish, fish, sesame or wheat do live with the risk of anaphylaxis.

The allergenic proteins in the "big" allergenic foods are NOT killed by cooking. That's dangerous misinformation - so please don't spread that around as you'll cause confusion.

Kris is right, though, that some researchers think that N.American processing may make peanuts more allergenic. But mostly research into allergy is centred on "the hygiene hypothesis" - a theory that our immune systems are "underworked" in a society in which every bacteria, parasite and germ is killed with an antibiotic or antiseptic.

Anonymous said...

In many of asian countries, we do not find many cases of peanut's allergies. DO you know why asian do not allergic to peanuts, and many news about allergic to peanuts in USA?

bfg said...

Did you get your vaccinations? A very common cause of food allergy is the peanut, soy, sesame, or fish oil in the vaccine adjuvant. This ingredient does not have to appear on the package insert so your doctor and you have no way of knowing that peanut oil is in the vaccine. This is a protected trade secret. Not every vaccine will have the peanut protein in it so not everybody becomes allergic from the vaccines.

Anonymous said...

My son IS allergic to both peanuts and green beans. A person allergic to peanuts is more like to be allergic to other legumes than someone who isn't allergic to peanuts. BUT that being said just b/c you are allergic to peanuts does not mean you will be allergic to legumes....just something to be tested for or be aware of..

Shelli (IA) said...

My son is 3 and he is allergic to peanuts, all beans except green, and peas. Doc said it is rare to be allergic to all of them however a blood test comfirmed. He was also allegic to Tomatoes (rare as well) that now he has out grown and milk and eggs that he has also out grown.

He as never had a breathing reaction however his levels of anti bodis are HIGH so we have to carry and epi pen and aviod all foods with any beans peas or peanuts.

Because peanuts and other legumes are in the family family the allergy can cross over it is exreamly rare to have it happen in mulipules but it does happen.