Common Food Allergy Facts and Figures
Many new parents wonder whether their child will develop food allergies. Although as many as one out of three parents report food reactions in their children, true food allergy involving the body's immune system affects, at most, 6 to 8 percent of children.
Knowing the Symptoms and Who's at Risk
Food allergy is a reaction of the body to certain proteins found in food. The reaction may be mild or severe to the point of being life-threatening. It also may be immediate or delayed.
Immediate allergy symptoms occur within minutes or up to two hours after the child has eaten the allergenic food. These symptoms may include any of the following: skin hives, itch or flushing, skin and mouth swelling, red itchy or watery eyes, runny nose, congestion, sneezing, difficulty breathing, wheezing, throat itching, repeated coughing, nausea, vomiting or diarrhea, abdominal cramps, weakness or dizziness. In its most severe form, the immediate allergic response leads to low blood pressure and the failure of circulation - a life-threatening reaction called anaphylaxis.
Delayed food allergy reactions include atopic dermatitis (eczema), asthma and gastrointestinal symptoms.
Also, children with atopic conditions - including seasonal allergies, atopic dermatitis and allergy-induced asthma -are at increased risk for developing a food allergy. A child with at least one sibling or parent with an atopic condition also is considered to be at higher risk for developing a food allergy.
Breastfeeding and Introducing Solid Foods
Human breast milk is the optimal source of nutrition for most infants and provides many health and developmental benefits. There is some evidence that exclusive breastfeeding during the first 4 months of life may decrease the risk of atopic disorders, including food allergy.
Many allergens from the mother's diet, as well as antibodies her body makes against them, are passed into the breast milk. Whether these allergens cause sensitization of baby's immune system and the development of allergy is controversial. Most studies show there is no relation between mother's intake and the development of her breast-fed baby's food allergies, and babies whose moms have eliminated allergy-prone foods from their diets do not appear to be protected from developing food allergies. There is even less evidence of a protective benefit from avoiding allergy-prone foods during pregnancy. The AAP currently does not recommend exclusion of allergy-prone foods from the diets of pregnant women.
There is no clear evidence that special formulas in which proteins are hydrolyzed, or broken up into smaller, less allergenic pieces, prevent the development of food allergies later in life. There is also no evidence that soy-based formulas prevent the development of food allergies.
Parents should introduce new foods watchfully, especially if the child is at higher risk for atopic conditions. The American Academy of Pediatrics recommends that introduction of solid foods, including rice cereal, be delayed until after 4 to 6 months of age to decrease an infant's risk for developing food allergy. Research is unclear on whether the introduction of allergy-prone foods should be further delayed in babies at higher risk.
Experts at one time recommended delaying the introduction of eggs until age 2, as well as the introduction of peanuts, tree nuts, fish and shellfish until age 3. However, more recent research has cast doubt on whether delaying these foods really decreases the incidence of food allergy, and some studies suggest it may actually increase the risk for atopic disorders. The AAP no longer recommends delaying these foods past the 4 to 6 months recommended for all other foods.
Like other solids, allergy-prone foods - such as eggs, peanut or other nut products, fish and shellfish - should be introduced carefully and one at a time. No more than one new food should be introduced for three to five days to avoid any question about which food is causing an allergic reaction, if it should occur.
Living With a Food Allergy
If you suspect your child has a food allergy or may be at risk for developing a food allergy, it is important to consult with your pediatrician or family physician about individual recommendations for you and your child. Your doctor may recommend simple skin or blood tests for specific allergies, and she or he may recommend exclusion of the suspected food from your child's diet for two weeks or longer, followed by a food challenge to see if the symptoms occur again.
If your child is diagnosed with a food allergy, it is essential for all caregivers to become well educated about avoiding allergens in restaurants, schools, store-bought food and other products. Your doctor may prescribe a pen with injectable epinephrine to use for anaphylactic reactions. Fortunately, while 80 percent of nut allergies persist into adulthood, most other food allergies are outgrown during childhood.
For further information on food allergies, ask your child's doctor and look at the Food Allergy and Anaphylaxis Network's Web site at www.foodallergy.org.
Dr. Larsen is a pediatric resident at Levine Children's Hospital of Carolinas Medical Center. Dr. Neuspiel is a general pediatrician at CMC-Myers Park Pediatrics and director of ambulatory pediatrics at Levine Children's Hospital.