Beware of elimination diet instructions (Part 1) – Don’t mess with the Big 8!

I have mixed emotions whenever I see an article on the Internet that instructs people on using an elimination diet to discover their food sensitivities. Of course, it’s not the idea of an elimination diet that bothers me – I have said many times that a properly done elimination diet and food challenges are the only way to diagnose food intolerance. These articles worry me when they suggest testing for sensitivities to foods that are on the list of Big 8 allergens. Simply put, don’t mess with these foods without consulting your doctor.

The Big 8 foods account for 90% of the food allergies in the US. (Interestingly, the most common food allergens vary by country.) The Big 8 foods are milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat and soybean. Other notable allergens include buckwheat, sesame, celery, mustard, and even corn. Fruits can also cause allergic reactions, and, quite frankly, it is possible to be allergic to any food, even if it isn’t commonly thought of as an allergen. Deadly anaphylactic reactions in adults are most often caused by peanuts, but any allergen can lead to a life-threatening reaction, even when your previous reactions were mild.

Adult-onset allergies

Did you know that it is possible for adults to develop food allergies after a lifetime of being able to eat anything? Allergies can start at any age, and adult-onset food allergies come with an increased risk for severe reactions.

Recently, doctors from Northwestern University [1] wanted to learn more about adult-onset food allergies, so they looked at the medical records of 1,111 patients from their allergy clinics. Fifteen percent of these patients were newly diagnosed as adults. In this group, the average age of onset was 31 years old, and 64% of patients were women. Shellfish and fish were the most common allergens, but all of the major allergens were represented.

If you think that you may have experienced an allergic reaction to a food in the past – even something as small as tingling in the mouth or a delayed reaction – ask your doctor for help in ruling out food allergies. For each person, the minimum amount of allergen required to produce a reaction is different. While the minimum amount for some foods is generally small (think peanuts), others often require larger amounts. When you ‘challenge’ yourself with a food to see whether you have a reaction, you don’t want to get into trouble by eating a large amount of something you wouldn’t normally eat. Even if your doctor allows you to do the food challenges on your own, it’s better to have asked than to be sorry later.

You might wonder why certain Internet MDs and nutritionists are giving out bad advice on testing for sensitivities to these allergenic foods. Unfortunately, they are basing their advice on misinformation from the alternative medicine community. Alternative medicine will have you believe that there is a lower grade of allergic reaction – originally referred to as food intolerance but now most often called a ‘sensitivity’ – that occurs when your IgG antibodies try to protect you from harmful foods. (A different antibody, IgE, is responsible for true allergic reactions.) As the story goes, IgG-based symptoms are delayed but never deadly. The truth is, these reactions don’t exist, and IgG antibodies are present in all of us as a sign that we can tolerate the foods that we commonly eat, like wheat, milk, eggs, soy, etc. Don’t mistake your mild but true allergic reactions for one of these ‘sensitivities.’ Even though food allergies often diminish over time, they will never cross over into a food sensitivity.

For more information on the common foods that produce allergic reactions (and for some interesting reading, too), check out these websites:

Stay tuned for a second article on this topic, where I will discuss the other conditions associated with these food allergens that you should talk to your doctor about.

Last updated September 25, 2015

© 2014 Anna (Laurie) Laforest. All rights reserved.
Photo © Can Stock Photo Inc. – The skeptic’s guide to food intolerance


1. Kamdar TA, Peterson S, Lau CH, Saltoun CA, Gupta RS, Bryce PJ. Prevalence and characteristics of adult-onset food allergy. The Journal of Allergy and Clinical Immunology: In Practice. 2015 Jan;3(1):114–115.e1.