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Preventing food allergies: Finding the why behind the when

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Nearly four out of every 100 children in the U.S. have a food allergy, according to CDC data from 2007. Avoiding common food allergens, such as peanuts, eggs, tree nuts and fish, for the first few years of life was the prescription for prevention for many years, but in 2008 the American Academy of Pediatrics reversed these guidelines, noting little evidence existed to say the avoidance was preventing food allergies. Newer expert recommendations have even suggested introducing these foods early could play a role in preventing allergies. An idea known as the “dual-allergen exposure hypothesis,” which has to do with when and how children are exposed to allergens, could be a reason why.

Last month, I had the chance to listen to allergy expert Gideon Lack speak on the hypothesis at an allergy panel discussion during the Association of Health Care Journalists (AHCJ) annual conference.

The dual-allergen exposure hypothesis is the theory that exposure to food allergens through the skin can lead to allergy, while consumption of these foods at an early age may actually result in tolerance, as Lack explains in a 2012 article. Depending on the balance of these exposures, either tolerance or allergy will “win.” Children with eczema, for example, have a disrupted skin barrier that could allow exposure to food proteins in the environment – such as peanut oil in creams or peanut residue on tables. Under the hypothesis, if these children avoid peanuts but are still exposed to them in the environment, they might be more likely to develop peanut allergy.

Lack told the audience about two studies that could shed some light on researchers’ understanding of the hypothesis and the development of food allergy.  One study is the LEAP Study, which involves a group of children assigned to avoid peanut-based foods until three years old and another group assigned to eat a peanut snack three times a week. The other is the EAT study, which is comparing breast-feeding plus feeding of allergenic foods with breast-feeding alone. However, Lack noted that very few evidence-based recommendations currently exist about when children should start eating allergenic foods, as health reporter Sandra Jordan explains in her blog on the AHCJ panel. With the prevalence of food allergy today, it will be interesting (and useful) to see where the future evidence from these studies falls.


Julianne Wyrick About the Author: Julianne Wyrick has a bachelor’s in biochemistry and is currently a master’s student in the health and medical journalism program at the University of Georgia, where she also writes about science for the Office of Research Communications. Find her on the web at Follow on Twitter @juliannewyrick.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. Kevbonham 1:48 pm 04/23/2014

    The skin thing is interesting – I hadn’t heard about that route of exposure. Definitely makes sense that ingesting should lead to tolerance, since our immune system has evolved to generally regard the stuff that we eat as non harmful (unless it’s invading past the epithelium).

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  2. 2. Lacota 11:11 pm 04/23/2014

    “noting little evidence existed to say the avoidance was preventing food allergies” as I understood it, we don’t expose babies to those substances because, if they are allergic, they are far more vulnerable to the effects and their parents are less likely to understand the signs. I didn’t know it was about trying to prevent allergies from developing.

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  3. 3. Kevbonham 11:58 pm 04/23/2014

    @ Lacota – I think both your explanation and Julianne’s can be true at the same time. Technically, prior exposure to an allergen is required to prime the immune response to it, so eliminating exposure will prevent an allergy from developing. If a young child already has the allergy, then they are likely more vulnerable (if only because they’re unable to know understand / communicate what’s happening on their own).

    That said, avoiding exposure to avoid developing the allergy seems a bit silly – if you’re avoiding all contact anyway, who cares if you have the allergy? The point that earlier in development, you might be more prone to develop toleragenic responses makes sense functionally and evolutionarily, it will be interesting to see what happens with these studies.

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  4. 4. u14023335 8:33 am 05/4/2014

    It is also believed that if a mother eats a wide range of foods during her pregnancy, she can help prevent any food allergies of in her child. Breastfeeding a child is still considered as the best way to make sure your baby grows up to be strong and healthy and without allergies. Trough breast milk the baby gets the exact amounts of every vitamin, mineral and fats that it needs to develop into a healthy child.

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  5. 5. ElneSs 3:52 pm 05/4/2014

    The most common allergies in children is peanuts along with milk, eggs, soy, wheat, tree nuts, fish, and shellfish. It is important for parents to know this because many parents do not recognize the symptoms of food allergies. I agree that mothers expecting a child should eat a wide variety of food during pregnancy to lower the chance of the child being allergic to types of food.

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  6. 6. hkraznodar 5:40 pm 05/6/2014

    I think we should wait for the results of these studies before jumping to conclusions. I would caution everyone from thinking that there is one ultimate diet for everyone. People are from ancestors that had very specific diets. Eating things that your progenitors have never eaten can sometimes lead to a wide variety of issues. We need to know a lot more about gut biota before buying in to blanket generalizations.

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