Any reaction you have after eating a food is an allergy

Earlier exposure to certain foods like peanuts can prevent future allergies. A 2008 study by the Journal of Allergy and Clinical Immunology compared food allergies among Jewish children living in the United Kingdom to those living in Israel, with peanut allergies occurring more frequently in the children living in the U.K. One main reason was that fact that 69% of the Israeli children were fed peanuts by nine months of age as compared to only 10% of U.K. children.