Which comes first: atopic dermatitis or food allergy?

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. One exceptional pair is food allergies and atopic dermatitis. Science has shown a strong link between these two, especially for moderate to severe atopic dermatitis, and especially in infants and young toddlers. (Atopic dermatitis is a form of eczema.) This article explores the science of which comes first for patients with both food allergies and atopic dermatitis.

Dr. Jon Hanifin, a respected dermatologist, recently gave a talk to colleagues. He discussed the link between food allergies and atopic dermatitis. The research he presented suggests that for some patients atopic dermatitis comes first and acts as a precursor to food allergies. For other patients, certain foods can exacerbate atopic dermatitis, and may or may not be true allergens.

Atopic dermatitis is often one of the first signs that a parent or caregiver notices in their child that helps lead to a food allergy diagnosis. As Dr. Hanifin explained, about 6-10% of children get an atopic dermatitis diagnosis, and of those with moderate to severe cases, about a third will get a food allergy diagnosis. Which begs the question: If parents notice signs of atopic dermatitis first, and food allergy diagnosis comes later, could atopic dermatitis cause food allergies?

What We Know:

  • In cases of food allergy, offending foods cause reactions in the body that involve the immune system.
  • Immunoglobulin E (IgE) antibodies are immune substances that are normally in our bodies at low levels, but are higher with food allergy
  • Allergy signs and symptoms often involve the skin, an important barrier that keeps most outside “things” from getting inside. This includes our digestive tract, which is like our skin-on-the-inside.
  • One factor in atopic dermatitis is “holes” in the barrier our skin provides.

What Dr. Hanifin Proposed:

In the past we thought that food allergies came first, causing both high IgE levels and atopic dermatitis. Dr. Hanifin suggested that “gaps” in the skin cause atopic dermatitis in some patients (likely due to genetics). This is a way that foreign substances could enter the skin and cause adverse reactions. He thinks that proteins that get through these gaps could allows the body to become sensitive to certain foods, leading to food allergies.

What does all of this mean? A big message here is that patients with atopic dermatitis, especially under five years of age, may have food allergies and may need testing to confirm them. An allergist should advise you whether or not testing is necessary. While avoiding food allergens may not help improve atopic dermatitis for everyone, it can certainly help some, and is always necessary if food allergies are present.

The second message is that food allergies and atopic dermatitis often occur together. However more research into the causes of atopic dermatitis and its relationship to food allergies is needed. Any research that leads to better health, by 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?

Rob McCandlish, RDN

Rob McCandlish is a registered dietitian nutritionist (RDN) who joined the Nutricia team in 2010. He has years of experience at Nutricia following food allergy research, working with Neocate products, talking with Neocate families and learning about the science behind Neocate and food allergies. Rob has two nephews who both used Neocate for their cow milk allergies!

Published: 03/17/2011
Rob McCandlish
Hi Brooke, great question. If nothing else in his routine or your diet has changed and you had been avoiding dairy, it's certainly possible that your son's rash could be related to changes in your diet. Protein fragments of foods a lactating mother eats can make their way into her breast milk. And there's definitely a sibling link when it comes to allergies: having an older sibling with allergies is common when younger children are diagnosed with allergies! However, those are common body sites for rashes that can have other causes. The best thing to do would be to ask his healthcare team how you can safely continue breastfeeding, possibly under medical supervision (in case you must avoid certain foods/ingredients and to get all the nutrients you need). Good luck!
My son just starting having a horrible rash on his checks, inside elbows and back of knees! He is 2 months and only been breastfed! Could it be from a glass of milk I had? It seems to just start once i drank milk? My other son is now 5 but when he was an infant he had a cow allergy and was on neocate formula.
Rob McCandlish
Hi Lizbeth - so sorry to hear your little one has atopic dermatitis. What you describe - fussiness, gas, crying, and atopic dermatitis - are all possible signs of cow milk allergy. However, they can also be totally unrelated. You should ask your daughter's pediatrician if they suspect food allergies. If so, they may recommend an elimination diet for you and a hypoallergenic formula for supplementing breast milk. Best of luck to you!
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