A food allergy is caused when your body mistakes a particular food as harmful. The body then releases histamines that cause an allergic reaction, presenting with one of the symptoms of allergic reaction. Food allergies in young children are more common than in adults and many children outgrow some of the food allergies.
The eight most common allergens, for children, represent 90% of all reactions in children:
Tree Nuts (nuts that grow on trees, such as Walnuts)