Scientists are aware of a relationship between food allergies and skin conditions like eczema, but the precise nature of that relationship has been unclear. Now, a new study led by Boston Children’s Hospital researchers and supported by the National Institute Of Allergy And Infectious Diseases (NIAID) illuminates a potential mechanism by which the skin and digestive tract are linked: scratching.

　　In a news release, the National Institutes Of Health—of which the NIAID is a part—describes the study, which indicated scratching a skin itch can create a chain reaction that leads to the expansion of certain types of cells in the intestine. People with atopic dermatitis, a type of eczema, often scratch their skin to relieve the itch, which scientists now think could lead to the expansion of mast cells in the intestine. When those cells expand, the intestine’s lining becomes more permeable by allergens.

　　The study was only conducted on mice, whose skin was covered and uncovered with tape to simulate scratching. The mice who “scratched” had more pronounced reactions to food allergens than the mice who did not “scratch.” When scientists analyzed tissue samples from four human children with atopic dermatitis, they found those children’s intestines contained higher-than-average mast cell counts. The findings are published in the journal Immunity.

　　The NIH notes that much more research is needed, but these early findings present the possibility that reducing scratching in children with atopic dermatitis could lead to less severe food allergies.