Understanding the natural history of food allergy in childhood is essential in managing patients with these disorders. The natural history of a food allergy includes information on the acquisition of the allergy, the likelihood that it will be outgrown, and its usual duration.
Food allergy most often begins in the first two years of life. Certain food allergies, such as those to cow's milk and hen's egg, are usually outgrown during childhood or adolescence, whereas peanut and tree nut allergies are more likely to persist into adulthood.
This topic review provides an overview of the natural history of food allergy in children. The clinical manifestations and treatment of food allergy are discussed separately. (See "Clinical manifestations of food allergy: An overview".)
DEFINITION OF FOOD ALLERGY
In this section, the terms "allergy" and "hypersensitivity" are used interchangeably to refer to an abnormal immunologic reaction to food. Such reactions can be mediated by IgE molecules directed against specific food proteins that activate mast cells and basophils, or can arise from other cellular processes involving eosinophils or T cells. (See "Clinical manifestations of food allergy: An overview".)
PREVALENCE OF CHILDHOOD FOOD ALLERGY
Most food allergy is acquired in the first or second year of life. The peak prevalence of food allergy is approximately 6 to 8 percent at one year of age, although rates as high as 10 percent have been reported [1-4]. It then falls progressively until late childhood, after which the prevalence remains stable at about 3 to 4 percent. The prevalence of food allergy in children (aged 0 to 17 years) has slowly increased in the United States, from 3.4 percent in 1997 to 1999 to 5.1 percent in 2009 to 2011 .