April 6 (UPI) -- Children's food allergies have been linked to genetics and environmental factors, including cleaning wipes and exposure to allergens, according to a study.
Researchers at Northwestern University found the allergies develop from a combination of genetics that alter skin absorbency, infant cleansing wipes that leave soap on the skin, skin exposure to allergens in dust and skin exposure to food by caregivers.
"This is a recipe for developing food allergy," Joan Cook-Mills, a professor of allergy-immunology at Northwestern University Feinberg School of Medicine, said in a press release. "It's a major advance in our understanding of how food allergy starts early in life."
The research was published Friday in the April issue of Journal of Allergy and Clinical Immunology.
An estimated 4 percent to 6 percent of children under the age of 18 in the United States develop food allergies, according to the Centers for Disease Control and Prevention. The rate of food allergy increased 18 percent from 1997 to 2007. Because there is no cure, strict avoidance of the food allergen is the only way to prevent a reaction.
Cook-Mills said she discovered the "perfect storm" for triggering food allergy by using clinical evidence about food allergy in humans, effects of food allergen and environmental allergen exposures and mice with genetic mutations that occur in humans.
Up to 35 percent of children with food allergies have atopic dermatitis, mostly from at least three different gene mutations that reduce the skin barrier.
She found exposing mice with the mutation to peanuts alone had no effect when exposed to the skin.
"Then I thought about what are babies exposed to," Cook-Mills recalled. "They are exposed to environmental allergens in dust in a home. They may not be eating food allergens as a newborn, but they are getting them on their skin. Say a sibling with peanut butter on her face kisses the baby. Or a parent is preparing food with peanuts and then handles the baby."
Then, she learned about previous studies involving the transmission of compounds through the skin by using sodium lauryl sulfate, a soap present in infant cleansing wipes.
The top skin layer is made of lipids -- fats -- and the wipes' soap disrupts that barrier, Cook-Mills said.
In another test, neonatal mice received three to four skin exposures of food and dust allergens and skin wipe chemicals for 40 minutes over two weeks.Then they were given egg or peanuts by mouth.
The result: mice reacted allergically at the site of skin exposure, in the intestine, and had a severe allergic food reaction of anaphylaxis that is measured by decreased body temperature.
The neonatal mice had normal-appearing skin and the dry itchy skin of dermatitis didn't develop until they a few months old, the equivalent of a young adult in human years.
How do you minimize the exposure?
"Reduce baby's skin exposure to the food allergens by washing your hands before handling the baby," she said. "Limit use of infant wipes that leave soap on the skin. Rinse soap off with water like we used to do years ago."
Cook-Mills is studying molecular responses in the skin that are unique to genetics and skin exposures. Ultimately, she hopes to find a way to block the development of food allergies, she said.