A new study suggests that dry roasted peanuts are more likely than raw peanuts to trigger an allergy.

Researchers at Oxford University have discovered that the body recognizes certain chemicals changes that occur during the roasting process at extremely high temperatures, which essentially “primes” the body to signal an allergic reaction the next time peanuts are consumed.

Such findings could explain why there are so many more people in the Western world who have severe peanut allergies, compared to people in Asia. In the West, it’s much more common to eat peanuts dry roasted, whereas in the East, the opposite is true.

First author author Dr. Amin Moghaddam says the results in mice suggest that the dry roasting process causes a chemical alteration of peanut proteins that activates the immune system against further exposure to peanuts.

In the study, researchers introduced peanut proteins to lab mice in three ways: directly into the stomach, applied topically to broken skin, and injected into the skin.

The mice that were initially exposed to dry roasted peanuts had a much greater immune system response, in comparison to mice that had been exposed to raw proteins.

“Allergies in people are driven by multiple factors including family genetic background and exposure to environmental triggers. In the case of peanut allergy, we think we may have discovered an environmental trigger in the way that peanuts are processed by high-temperature roasting,” said Moghaddam in a statement.

The findings of the study are published in the Journal of Allergy and Clinical Immunology.