Eczema and Peanut Allergy: What’s the Connection?
Can food allergy cause eczema?
Although food allergy is more common in children who have eczema, they are separate conditions. Food allergy does not normally cause eczema, but having eczema may increase the chance that a food allergy develops.
Healthy skin acts as a protective barrier and helps prevent substances like food allergens from getting into the body through the skin. Healthy skin helps protect the immune system from being exposed to food allergens. When your child’s eczema is under good control, your child’s skin is better at preventing food allergens from getting in.
Research suggests that when your child’s skin is scratched open, food allergens can get into the body more easily to make contact with the immune system. Direct contact between open skin and food, such as peanuts, may increase the chance that an allergy will develop to that food.
The immune system may be more prone to developing a food allergy if the first exposures to the food are through scratched open skin.
However, if the immune system is first introduced to the food (peanut, e.g.) by eating it, the immune system may more likely tolerate the food, since the first exposure is through the digestive tract.
It was previously thought that peanut allergy in children started about age 3, 4, or 5. However, new research suggests peanut allergy develops much earlier. The study involved 640 infants aged 4-11 months with eczema.
Researchers measured blood levels of immunoglobulin E (IgE), an immune system protein the body makes in response to allergens. A positive result means a person is sensitive to and likely to be allergic to a certain food. The results showed:
- 23% of the infants were sensitive to peanuts.
- 31% were sensitive to cow’s milk.
- 22% were sensitive to sesame.
- 16% were sensitive to Brazil nuts.
- 20% were sensitive to hazelnuts.
- 21% were sensitive to cashews.
- 14% were sensitive to almonds.
Sixteen percent of the infants tested positive for more than four foods.
A more recent study called LEAP (Learning Early about Peanut Allergy) was designed to answer the question: “Can early (before one year of age) introduction of peanut decrease the risk of developing peanut allergy?” — and the answer was a resounding ‘Yes”.
The LEAP study also posed the question of whether we should do anything differently now that we have the study results. There are strong recommendations based on these results.
- Children, under one year of age, at increased risk for peanut allergy because of severe eczema or food allergy should be skin tested to peanut.
- If the skin test is negative or mildly or moderately positive, consider a peanut challenge in a controlled medical setting.
- If the infant passes the peanut challenge, they should eat the equivalent of four peanuts at least three days a week until at least age five.
Because even a child with a negative skin test, but with severe eczema or egg allergy may react to peanut, the first exposure to peanut should always be supervised by an allergist/immunotherapist experienced in performing food challenges.