Why does eczema put your baby at greater risk for developing food allergies?
While we don’t know for sure why babies with eczema are at greater risk for food allergies, we do know a few factors that could be at play, thanks to recent research. Today, we’ll cover what parents need to know about these factors.
Eczema is the most significant risk factor for developing food allergies. Up to 67% of infants with severe eczema, and 25% of infants with mild eczema, will develop a food allergy.
But why does eczema increase baby’s food allergy risk by so much? We don’t know for sure, but two possible causes could be babies’ broken skin barrier and the growth of the bacteria that causes staph infections. We also know that a progression called the “atopic march” is involved, because eczema and food allergies are closely related conditions. Today, we’ll cover what parents need to know about these factors that may put eczema babies at greater risk for food allergies. We’ll also cover what parents can do to help prevent food allergies in eczema babies.
The Atopic March
The atopic march (or allergic march) describes how children with one allergic condition are at increased risk for others, and how allergic conditions tend to appear in a certain order (one condition usually “marches” after the other).
Eczema and food allergies are both considered allergic conditions. Both eczema and food allergies are part of the atopic march.
In the atopic march, eczema comes before food allergies in the “marching order”— eczema is a precursor to food allergies.
This means that babies usually develop eczema before food allergies, and developing eczema means a baby is at increased risk for a food allergy. If babies develop eczema symptoms, they’re more likely to develop food allergy symptoms later on.
Learn more about the Atopic March from MD Magazine and Chief of Allergy at Children’s Hospital of Philadelphia (CHOP) Dr. Jonathan Spergel:
Staph Bacteria and Baby Eczema
The exact reasons why eczema increases food allergy risk still remain unknown, but one study suggests that Staphylococcus aureus (the skin bacteria that causes staph infections) may play a role. Staph infections are most common in people who have eczema.
In an analysis based on results of the LEAP study, researchers found that babies with severe eczema were more likely to have S. aureus, and babies with severe eczema were at higher risk for a food allergy if they had S. aureus colonization.
Researchers also found that children with severe eczema and staph bacteria produce high levels of IgE antibodies to peanut, egg and milk. When someone has a food allergy, they produce specific IgE antibodies that cause the immune system to fight off these food proteins, and that trigger a food allergic reaction. High levels of peanut-specific, egg-specific or milk-specific IgE antibodies in someone’s body are a sign that someone has allergies to that food.
So, staph bacteria appears to be related to food allergy development in children with eczema, although we don’t know for sure.
For more on the findings from the LEAP study that show a relationship between eczema, S. aureus bacteria and food allergies, read our article here.
The Broken Skin Barrier
Eczema babies’ skin barrier may be another reason why they’re at greater risk for food allergies.
Usually, someone’s skin barrier is like a strong protective wall. The barrier helps keep moisture in the skin, and keep irritants and allergens out.
But babies with eczema have a compromised skin barrier—one that easily lets irritants and allergens pass through, like a wall with cracks.
Why might this compromised skin barrier put eczema babies at greater risk for food allergies?
According to what scientists call the dual allergen exposure hypothesis, exposure to allergy-causing foods via the skin may increase babies’ food allergy risk. If allergens like peanut, egg and milk proteins pass through your baby’s skin barrier often enough, they may lead your baby to develop an allergy.
Normally, a baby’s skin barrier helps prevent these food proteins from passing through the skin.
But since eczema babies have a compromised skin barrier, it’s a lot easier for common food allergens to pass through their skin barrier.
When eczema babies’ skin touches the proteins from allergy-causing foods, like peanut residue on a table, milk in a skin cream, or egg proteins on a high chair, their weakened skin barrier easily lets the proteins pass through. So, they end up with more exposure to these allergens through the skin than babies without eczema. This increased exposure through the skin may make eczema babies more likely to develop a food allergy.
Food Allergies in Eczema Babies
Fortunately, there’s an important step parents can take to help prevent eczema babies (and all babies) from developing a food allergy. Feeding your baby common allergy-causing foods, like peanut, early and often is recommended by new USDA guidelines.
As the dual allergen exposure hypothesis explains this, exposure to allergens on the skin is “negative” exposure that may increase food allergy risk. But exposure to allergens by eating them is “positive” exposure that helps prevent food allergies.
If your baby eats allergy-causing foods early and often enough, this enables your baby’s immune system to build up tolerance to the food proteins. This protects your baby from developing a food allergy. But if your baby doesn’t eat allergy-causing foods regularly enough, your baby will be more likely to develop a food allergy.
This is why it’s especially crucial for babies with eczema to eat peanut, egg and milk early and often. Eating these foods early and consistently enough helps balance out all the “negative” peanut exposure eczema babies will likely receive through the skin, and works to help prevent food allergies.
The results of several landmark clinical studies (LEAP, EAT, PETIT) show that early and consistent allergen introduction helps prevent food allergies. To help your baby build up a tolerance, you’ll need to start feeding baby common allergy-causing foods as early as 4-11 months of age (the earlier after 4 months, the better). You’ll also need to sustain exposure, by feeding your baby these foods multiple times per week for at least 3-6 months.
Since eczema babies are at the greatest risk for food allergies, early and consistent introduction is especially important if your baby has eczema. We might not know why eczema babies are at increased risk for food allergies, but we do know early and consistent introduction is recommended.
The USDA’s new 2020-2025 Dietary Guidelines for Americans are based on landmark clinical food allergy prevention studies. These guidelines recommend feeding allergenic foods such as peanut and egg starting at 4 months of age for every baby, including those with eczema, without any prior screening required. Learn more about the USDA guidelines here.
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