In food allergy circles, we usually think of symptoms and side effects as results of food allergies, not the other way around. In most cases that’s true. Science has shown a strong link between food allergy and atopic dermatitis, a form of eczema. Last month Dr. Jon Hanifin, a respected dermatologist, gave a talk to colleagues discussing the link between atopic dermatitis and food allergies. The research he presented suggests that for some patients it may actually be atopic dermatitis that comes first and acts as a precursor to food allergies.
Atopic dermatitis is often one of the first signs that a parent or caregiver notices in their child which helps lead to the diagnosis of food allergy. As Dr. Hanifin explained, about 6-10% of children are diagnosed with atopic dermatitis, and of those about a third will be diagnosed with a food allergy. Which begs the question: If parents notice signs of atopic dermatitis first, and an allergy diagnosis comes later, couldn’t atopic dermatitis be causing some instances of food allergy?
What We Know:
-In cases of food allergy, offending foods cause reactions in the body which involve the immune system
-Immunoglobulin E antibodies (IgE) are immune substances which are normally in our bodies at low levels, but are higher with food allergy
-Allergy symptoms often involve the skin (including our digestive tract, which is like an inside skin), an important barrier that keeps most outside “things” from getting inside
-One factor of atopic dermatitis is “holes” in the barrier our skin provides
What Dr. Hanifin Proposed:
In the past it was assumed that food allergies came first, causing both high IgE levels and atopic dermatitis. Dr. Hanifin suggested that in some patients atopic dermatitis is caused by “gaps” in the skin (likely due to genetics), which means that foreign substances can enter the skin and cause adverse reactions. He thinks it may be proteins that get through these gaps which allows the body to become sensitive to certain foods, leading to a food allergy.
What does all of this mean? The biggest message here is that patients with atopic dermatitis, especially those under five years, should be tested for food allergies. While avoiding food allergens may not help improve atopic dermatitis, it could certainly prevent or improve other serious side effects of allergies. The second message is that more research needs to be done into the causes of atopic dermatitis and its relationship to food allergies. Any research that leads to better health, through reducing instances of atopic dermatitis and/or food allergies, is good research! Tell us about your experience: Was atopic dermatitis the first sign that you saw of your child’s food allergy?