Skin exposure to food allergens contributes to sensitization to foods like peanuts in early life, according to a study by Icahn School of Medicine. The finding partly explains why most children become sensitive to peanuts even before they first eat them.

The researchers said that studies on the origins of allergies are important as some of them tend to be lifelong.

Previous studies showed that children first become allergic when exposed to peanut proteins either through breast milk or house dust.

However, the current study has found skin exposure to be one of the high risk factors for peanut allergies among children. Doctors should take the skin factor into account during future treatments or preventive efforts.

"The peanut protein responsible for most allergic reactions in humans is seen as foreign or dangerous by the immune system of the skin," said Cecilia Berin, PhD, Associate Professor of Pediatrics, in a press release. "Blocking those immune pathways activated in the skin prevented the development of peanut allergy in the mice, and our next step will be to confirm this in humans."

For the study, the researchers subjected mice to peanut protein extract on the skin and found that frequent exposure to peanut allergens triggered sensitization and a severe, whole-body allergic reaction following a second exposure.

"This research helps us to understand why peanut, out of the many foods in our diet, is such a common cause of food allergy," said Berin."If we identify how the immune system recognizes peanut as a danger, we may eventually learn how to block that pathway and prevent the food allergy altogether."

The finding is published in the Journal of Clinical Investigation.