New research shows that healthy infants have intestinal bacteria that prevent the development of food allergies.

Researchers from the University of Chicago, Argonne National Laboratory and the University of Naples Federico II in Italy found that when gut microbes from healthy human infants were transplanted into germ-free mice, the animals were protected from an allergic reaction when exposed to cow’s milk. Gut microbes from infants allergic to milk did not offer the same protection; mice receiving these bacteria suffered an allergic reaction when given cow’s milk. Cow’s milk allergy is the most common food allergy affecting children.

The study, published this week in Nature Medicine, also identifies a specific bacterial species that protects against allergic responses to food. “This study allows us to define a causal relationship and shows that the microbiota itself can dictate whether or not you get an allergic response” said Cathryn Nagler, PhD, the Bunning Food Allergy Professor at UChicago and senior author of the study.

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