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What is a "food allergy?"

Posted: Feb 16th, 2010 at 10:58 am

I wanted to address this as a serious question, away from the multi-page thread that has become pretty non-productive.

After reading some of the posts this weekend, I went back to a good starting place: Dr. Wood's book "Food Allergies for Dummies." It's a pretty good resource book for the basics on food allergy.

On the very first page, he poses the question: "What's an Allergy and What's Not?" Here is part of that discussion:

"Due to a lack of accurate information and an overabundance of misinformation about food allergies, many people have developed misconceptions about what a food allergy really is. Some people think that if you get sick after eating a particular food, you're allergic to that food. Others think that if a food makes you tired, you're allergic to it, or that a craving for a particular food is a sign of allergy, or if your pulse rate rises after eating, you're allergic. The general public often lumps every adverse symptom they have after eating a food as an allergic reaction when this, in fact, is not the case."

"So what exactly is a food allergy? A food allergy is an immune system response that creates antibodies to attack substances in a food that your immune system identifies as harmful to you. In the process, the reaction releases huge stores of chemical substances, including histimines, which cause symptoms ranging from a mild case of hives to a potentially life-threatening system shutdown."

Then he talks about "Identifying imposters" by saying "Foods can make you feel sick for a variety of reasons, most of which have nothing to do with food allergies. This leaves the door open for quackologists selling all sorts of ineffective cures and treatments for a host of ailments that they falsely attribute to food allergies. To avoid getting sucked in by misinformation, be aware that the following ailments are rarely, if ever, related to food allergies:" Then he lists things like food intolerances, food poisoning, histamine poisoning, reactions to food additives and other common ailments like migraine headaches and irritable bowel syndrome. He says "don't waste your time chasing the food allergy ghost."

On Dr. Wood's website (and also in his book), he talks about IgG testing:

"I see patients every week who have had IgG testing for food allergy, in which their blood was tested for IgG antibodies instead of IgE antibodies (the antibodies typically associated with allergies). These patients often come in on extremely restricted diets because they had tested positive to so many things. This is no surprise though because a normal immune system is supposed to make IgG antibodies to foreign proteins, and a positive IgG test to a food is therefore a sign of a normal immune system rather than a sign of food allergy."

In his book, he says about IgG tests: "They do not predict true food sensitivity and can lead to recommendations that result in malnutrition."

6 year old DS with LTFA to peanuts, tree nuts, eggs and flax seed. Avoiding some fish and shellfish.

Posted: Feb 16th, 2010 at 11:24 am

Thanks for this! Could we sticky it at the top for the time being? It seems like very important information for the Main forum.

Committee Members
Posted: Feb 16th, 2010 at 11:25 am

Happy to help.

Stickied for time being.

Registered for the purpose of Committee Member role 2008 - 2009, and 2011 - 2012.


Posted: Feb 16th, 2010 at 11:39 am

I agree-- so important to understand this, particularly as you're starting out.

Lots of physicians will order tests, but then fail to discuss their meaning with patients, leaving them to wonder just WHAT they should be avoiding.

On a related note-- why is it important NOT to avoid things you ARE NOT allergic to?

  • children (and to a lesser extent, adults) can develop SERIOUS nutritional deficienties that have life-long health consequences,

  • true food allergy is potentially life-threatening, and therefore, can be quite restrictive in terms of lifestyle (limiting social, educational, and employment options),

  • disordered eating patterns can develop and also be difficult to correct, and finally

  • there is some evidence that avoidance beyond what is necessary for management might be capable of provoking/worsening allergy or intolerance.

This is why, even with a positive TEST result, it is important to make sure that those results make sense in light of the patient's HISTORY.

A person that has been scarfing down hummus every day for lunch and feels generally fine... is probably not really allergic to sesame. KWIM? On the other hand, a person who has non-specific symptoms all the time and seven or eight (or more) positive test results to a variety of foods needs further investigation to determine the underlying cause of those symptoms. Gall bladder disease, celiac and other auto-immune disorders may initially present as possible 'food allergies.' Those conditions are quite serious-- and need correct diagnosis and treatment.

Bottom line is that getting to the bottom of test results that seem strange or unlikely is pretty much always advisable. Smiley

insert pithy phrase here


Posted: Mar 23rd, 2010 at 08:24 am

Although it's quite anxiety provoking to try a new food, it's very empowering to find another food that is safe!

We had a psychologist speak to our local group about anxiety and it is much higher in those with anaphylaxis food allergies-no surprise Smiley . Opening up our dietary world and having good experiences builds resilience which, in turn, helps to minimize anxiety.

It's so important to find a good allergist who will work with you. Annual appointments provide opportunities to test suspected foods. Keeping an allergy diary is helpful in determining what is really going on.

Me-allergic to birch pollen and slight Oral Allergy Syndrome
dd-allergic to egg,milk, peanut, tree nuts, most legumes, penicillin, well controlled asthma
pet cat-allergic to beef, pork and lamb

Posted: Aug 3rd, 2010 at 08:21 pm

I'm surprised something like this hadn't been already available and stickied, Right?

Glad you did this. Smiley

I'm shocked about the IGg I always thought that it was way different but I still a respected measurement of food intolerance of some sort.