Food allergies occur when the immune system identifies the proteins in a particular food as harmful to the body, subsequently reacting to try to "fight off" the "harmful" proteins. Between two and eight percent of American children have food allergies. The most common food allergies in infants and children are:

  • Cow's milk
  • Eggs (especially egg whites)
  • Peanuts (groundnuts)
  • Tree nuts (including almonds, Brazil nuts, hazelnuts and walnuts)
  • Soy
  • Wheat

In adults, milk, egg and soy allergies are less common while fish and shellfish allergies are more common. This can be explained because most children grow out of their milk, egg and soy allergies, while young children don't eat very much fish or shellfish and therefore don't develop allergies or their allergies are not known. Nut allergies are common in adults as well as in children because these allergies are rarely outgrown. Only about 20 percent of children outgrow peanut allergies and about nine percent outgrow tree nut allergies.

If your infant has food allergies he may have symptoms of the skin such as itchiness, rashes or swelling; gastrointestinal symptoms such as abdominal pain, diarrhea or vomiting; or respiratory symptoms such as difficulty breathing. An allergist can test your child for allergies with a blood test or a skin prick test. If he is diagnosed with food allergies, you'll have to read food labels carefully to ascertain whether there might be traces of the allergen in product you wish to purchase. Depending on the severity of the allergy, you may have to prevent your child from coming into contact with the allergens at all and you may need to carry epinephrine with you so you can treat him immediately if he has a severe reaction.