Food allergies: immunological reactions to food

Allergic reactions to food are mediated by the immune system, can be consistently reproduced, and cause a change in the target organ. An estimated 0.3% to 20% of infants are affected. The incidence decreases with age to about 1% to 3% in adults. Development of food allergies depends on heredity, intestinal permeability, immune responsiveness, and exposure to food. Common symptoms include gastrointestinal, skin, or respiratory disturbances that occur from seconds to several hours after food ingestion. Although the skin-prick test is the most reliable diagnostic test, positive results must be followed by a trial elimination diet and food challenge to determine whether symptoms appear after food ingestion. Food allergies are treated by the elimination of the offending foods from the diet. Breast feeding is usually recommended to reduce the incidence of allergic disease in infants. The dietitian's expertise is particularly valuable in assessing the nutritional status of the allergic person, assuring nutritional adequacy during treatment and maintenance, and participating in research to address the many unresolved issues surrounding food allergies.