The skin is a powerful barrier that prevents things from the environment, such as bacteria and allergens, from getting inside of a person and causing harm. A new study has shed light on the development of food allergies and that they may develop as a skin reaction. The researchers found that children who have had eczema are six times more likely to develop food allergies to egg, cow's milk, and peanuts than children who did not have a skin condition.

Researchers analyzed more than 600 three-month-old babies from a British study called EAT (Enquiring About Tolerance). All the children in the study were breast fed from birth, examined for eczema, and genetically tested for factors that were known to contribute to eczema. The children were also tested for the six most common allergies and found that the most prevalent one was to egg white, followed by milk and peanuts. Independent of genetic factors, children who had more severe eczema showed an increase in sensitivities to foods as allergens. The researchers, however, warn that skin tests don't always indicate an actual food allergy.

The researchers speculate that immune cells in the skin can become exposed to environmental antigens and lead to an inflammatory reaction. "This is a very exciting study, providing further evidence that an impaired skin barrier and eczema could play a key role in triggering food sensitivity in babies, which could ultimately lead to the development of food allergies," said Dr. Carsten Flohr, NIHR Clinician Scientist and Senior Lecturer at King's College London.

"This work takes what we thought we knew about eczema and food allergy and flips it on its head — we thought that food allergies are triggered from the inside out, but our work shows that in some children it could be from the outside in, via the skin. The skin barrier plays a crucial role in protecting us from allergens in our environment, and we can see here that when that barrier is compromised, especially in eczema, it seems to leave the skin's immune cells exposed to these allergens. It opens up the possibility that if we can repair the skin barrier and prevent eczema effectively then we might also be able to reduce the risk of food allergies."

Source Flohr C, Perkin M, Logan K, et al. Atopic Dermatitis and Disease Severity are the Main Risk Factors for Food Sensitization in Exclusively Breastfed Infants. Journal of Investigative Dermatology. 2013.