Saturday, February 03, 2007

Corn Allergens and Protein (Reader Question)

Here's a question from a reader:

Hi. I read some of what you wrote on the corn avoider blog. Thanks for what you've written. I was just diagnosed with a corn allergy and am trying to figure out what that means for me. I have a question for you or any of your other corn avoiding writing buddies.

So, my limited understanding of allergies is that they are a reaction to protein. Many of the corn avoidance sites mention avoiding corn derivatives. Do things like dextrose or corn starch or corn syrup have corn proteins in them? It doesn't seem like they would, especially the medical grade IV stuff.

Are there just trace amounts which are harmful to people who are severely allergic? Or are people maybe allergic to molds that form on the corn, and the mold proteins aren't eliminated during the processing into syrup or starch etc?

Please let me know what you think and if you've found any research that might shed some light on this question.

Thank you so much.


Hi, Anika. Thank you for writing. I'm sorry to hear about your corn allergy.

Unfortunately there is no hard-and-fast rule about what substances will be allergenic for which people. It really depends on your level of tolerance whether you will react to something or not.

My daughter is so sensitive that she reacts even to things that supposedly contain no protein at all.

Dextrose and corn syrup are made by taking corn starch and separating the protein from the sugar. The sugar portion is corn syrup, or when more highly refined it is dextrose or glucose. Theoretically, chemically pure dextrose should contain no protein. But the dextrose used in food products generally is not chemically pure and can contain some corn proteins.

Derivatives that are highly refined, like microcrystalline cellulose made from corncobs, corn alcohol, glycerine, glucose, and xanthan gum or citric acid grown on corn supposedly have no protein. But some people who are highly sensitive to corn do react to them anyway. There are documented cases of allergic reactions to dextrose IV solution, for example.

Unfortunately, the only really accurate way to figure out your own level of tolerance is to remove all corn derivatives from your diet for a few weeks and then start adding some of the less-allergenic derivatives. A reaction may happen immediately or it may take several days of eating the food regularly for a reaction to build up.

Some people find that they can tolerate tiny, very occasional amounts of corn derivatives, but that they have problems if they eat them too much in quantity or frequency. Others can tolerate certain derivatives like corn-derived citric acid, but will react to things like corn syrup and corn starch.

Science really doesn't completely understand allergies. It's debatable whether proteins are the only allergenic substances in foods, although most allergic reactions do seem to be caused by proteins. However, even products like refined oils (and certainly cold-pressed or expeller-pressed oils, which are less highly refined) can contain trace amounts of proteins.

According to some research done by the owner of Yummy Earth products, current tests for corn protein can only detect levels around 50 ppm (parts per million), while tests for peanut, for example, can detect amounts down to 1ppm. So even a test negative for corn protein doesn't mean that there is not enough protein in the product to cause problems for someone who is severely sensitive.

A good example is Red Star SAF yeast. Their yeast, like nearly all commercial yeast, is grown on corn syrup. They certify that there is no corn protein or corn DNA in their yeast, yet a number of people allergic to corn have had adverse reactions traced to the yeast.

Molds do grow very easily on corn (and also many of the corn derivatives are grown using molds), and most corn products are processed using sulfites, so people who are highly allergic to either one of those will probably have issues with most corn products. If this is an issue, sometimes people will be able to tolerate very fresh, well-washed corn straight from the field while having issues with other corn products. Also, fresh corn contains less of some allergenic substances than dried corn does, supposedly.

I'm working on compiling some information looking at various studies and research about corn allergy, and will post it here on the no-corn blog when I finish it. Meanwhile, I can recommend the best resources I know of for learning about corn allergy--the corn avoiders delphi forum, the corn-free list, and the list of corn derivatives on Connors' site. All those are linked in the sidebar of the News for Corn Avoiders blog. You'll also find links to several recipe blogs and other resources here.

Thank you again for writing. I hope some of this is helpful. Maybe some of the others will have something to add, also.

Best wishes in figuring out your own level of tolerance.


Stacey said...

I'm getting my PhD in Immunology and every day I face my colleagues having disbelief at my allergy when I state that I'm not just allergic to the corn protein. An allergy fellow (MD) working in my lab even suggested that I wasn't really allergic to corn, but rather allergic to sulfites because corn syrup has sulfites. *rolls eyes*

What I find most interesting in all of this is that any one studying the immune system knows that various cells are equipped to respond to bacterial glycoproteins and sugars. I have no idea, but it makes sense to me that in some way for those of us allergic, something has gone wrong and our body sees corn things as bad. Especially for those of us who have atypical non-anaphylatic reactions that aren't IgE based.

Medical doctors and scientist are so dogmatic that it takes time and much proof to change their minds. Maybe someday...

Anonymous said...

Could you please expand on your "Especially for those of us who have atypical non-anaphylatic reactions that aren't IgE based." Comment. We have a child with multiple severe medical problems most of which appear to us to be food driven. CORN is the worst.

Anonymous said...

This list is fairly good at listing reaction symptoms which are generally atypical and non-anaphylatic. Allergies cause a whole host of problems and often symptoms are misdiagnosed as something else or attributed to something else.

Anonymous said...

Sorry running on very little sleep. What list?

Anonymous said... Sorry.. this list of allergens.